PALEOTORUS: The Laws of Morphogenetic Evolution Mark A. S. McMenamin 2009 Meanma Press 2 Meanma Press South Hadley, Massachusetts, USA ©2009 by Mark A. S. McMenamin All rights reserved. McMenamin, Mark A. S. Paleotorus: The Laws of Morphogenetic Evolution/Mark A. S. McMenamin ISBN 1‐893882‐18‐7 ISBN 978‐1‐893882‐18‐8 Printed in the United States of America c 10 9 8 7 6 Cover Illustration: Helicoplacus gilberti Durham and Caster 1963. Middle Poleta shale, Blanco Mountain Quadrangle area, White‐Inyo Mountains, California. 3 Contents Page Introduction: The Collapse of Conventional Darwinism 5 Chapter 1: Paleontology and Morphogenetic Fields 12 Chapter 2: An Ediacaran Toroid from Namibia 19 Chapter 3: Parazoans and Metazoans: Testing the Morphogenesis Model 23 Chapter 4: A New Giant Trilobite 27 Chapter 5: Scleritome Morphogenesis 33 Chapter 6: Vertebrate Teeth and Zahnreihen (with Amanda Lepelstat) 42 Chapter 7: The Schadian Torus 55 Chapter 8: Cephalopod Hypertorus 57 Chapter 9: Convergent Forams and Iterative Evolution 61 Chapter 10: Summary and Conclusions 71 Acknowledgments 74 Appendix A: Systematic Paleontology 75 Appendix B: New Ellesmeroceratid and Tarphyceratid Nautiloids from the Franklin Mountains Area, El Paso, Texas (with Katherine Malone) 87 Appendix C: McKelligon Canyon/Sugarloaf Mountain Freshly Exposed Section of the Florida Mountain Formation (pars), measured March 13, 2008 References 92 96 4 5 Introduction: The Collapse of Conventional Darwinism THE YEAR 2009 marked several important Darwinian anniversaries, and yet with great irony, Neo‐Darwinism simultaneously found itself in a sorry state, staggering under attack by scientists who were finding its main tenets a bit hard to swallow. Charles Darwin himself was acutely aware of the problems that were eventually to spring to life in 2009. Stephen Jay Gould noted that “the fossil record . . . caused Darwin more grief than joy. Nothing distressed him more than the Cambrian explosion.” Darwin admitted, in On the Origin of Species, that the abrupt emergence of animals at the base of the Cambrian (about 543 million years ago) could invalidate his views on gradual evolution by natural selection. Darwin saw what is now called the Cambrian Explosion as a striking anomaly. Charles Walcott, director of the United States Geological Survey and discoverer of the Burgess Shale fauna, proposed a Lost or Lipalian interval to explain the Cambrian anomaly. Walcott felt that there must be strata missing in the stratigraphic record that had at one time contained the fossils of Darwin’s hypothesized, gradually evolving Cambrian ancestors. The strata had since been eroded away in a global washout that formed a gigantic gap in the strata, the so‐called Great Cambrian unconformity of the Lipalian Period. Walcott’s views on the matter have since been proven wrong, as plenty of strata have been discovered (I helped co‐name some of these formations) to fill in the supposed stratigraphic gap between Cambrian and pre‐Cambrian strata. Indeed, the Cambrian anomaly has, if anything, grown worse since the 1859. Pierre Teilhard de Chardin was among the first to point to cracks in the Darwinian edifice: “By identifying transformism [macroevolution] with its mechanistic or material forms, and more especially Darwinism, many have misjudged it” (Teilhard 1957). There is a profound contrast between the organisms of the late Precambrian, mostly microbes and soft‐bodied creatures of uncertain affinity, and the abundant Cambrian animals that burst forth in an evolutionary radiation as the recognizable members of modern animal phyla. This abrupt transition presupposes either a Lipalian interval of hidden evolution, as Walcott argued to help defend Darwin, or a breathtakingly rapid pace of phylum level evolution (macroevolution). We therefore are left with the Cambrian Explosion, Cambrian Event, or what might best be called the Cambrian Anomaly. This anomaly, this gap in our knowledge, this cognitive unconformity, is a collective embarrassment for science in general. Because of this, we are entering exciting times in biology. We might call this the age of post‐natural selection evolutionary biology, in other words, a kind of post‐modernism for the natural sciences. The Darwinian fixation on natural selection and its consequent pan‐selectionism have proved inadequate for the demands placed upon them, and now we must look elsewhere for a fuller understanding of the evolutionary process. A paradigm shift of the first order is in the process, making this 6 an especially good time to review our understanding of the scientific process as we seek a way forward. Nicolas Steno (the founder of modern geology, who may someday become another St. Nicholas because of his service to the Church) once said of the scientific method that science “does not admit of any set method, but must be attempted in every way possible.” As I recently pointed in Nature News (Dolgin 2009), evolutionary biologists can behave as an entrenched group reluctant to consider alternate ideas. This is expressed in attitudes such as “only biologists should do biology,” which is actually code language for, as so nicely put by Michael A. Flannery, suppression of anything that “offends their hidebound reliance upon methodological naturalism as the only thing that ‘counts’ in science.” Creationists, understandably desperate for a more faith‐friendly science, have lavishly underwritten several Intelligent Design think tanks. This nascent research community has followed a number of red herrings, and been accused of conducting pseudoscience or worse, but is finally settling in on some topics, such as the rapidity of the Cambrian morphological transition and the origin of life problem, that will actually force serious and thoughtful responses from the broader community of conventional students of evolution. This book may be considered such a response from a more conventionally‐oriented, yet open‐minded, scientist. In a departure from the usual charges, counter charges, god of the gaps fallacies, and ad hominem attacks, some actual scientific progress is about to occur, so we may eventually be able to say that the Intelligent Design funds were not entirely spent in vain. People with a serious interest in evolutionary theory, but who are not professional scientists, are also joining the discussion. I welcome these newcomers, as they bring fresh perspectives and new ideas that are absolutely critical for the kind of lateral thinking that can really advance the science. At times these new approaches can seem to be unsophisticated or even exaggerated. But this is exactly what is required in times of hidebound thinking. As G. K. Chesterton put it, “All the exaggerations are right, if they exaggerate the right thing.” What is really at stake here is our understanding of evolution. Darwin proposed descent with modification, an evolution by means of natural selection. The concept of natural selection, however, is proving to be less and less viable as a mechanism for major evolutionary change. Or even a mechanism for generating any kind of biological novelty. The late Stephen Jay Gould challenged natural selection from the standpoint of his emphasis on the importance of contingency in evolution. He argued that an overemphasis on adaptationisitic thought hampers our understanding of evolution. Ironically, Gould’s rivals, some of whom take a highly deterministic view of evolutionary progress, seeing evolution as an inevitable and even predictable process, also implicitly de‐emphasize natural selection in the following way. If the same forms are going to reappear repeatedly, then natural selection is beside the point—the forms are going to appear anyway, via any number of a variety of processes. Some unknown process (evidently not natural selection) guides them to the same morphological destinations time and time again. Thus, natural selection is attacked by both camps on either side of the contingency‐inevitability debate in evolutionary biology. A major dimension of this debate is the realization, first emphasized by Pierre Teilhard de Chardin, of the ubiquity of convergent evolution. The convergences are so close, as for example between African vultures and American vultures (descended from hawks and storks, respectively), as to 7 lead the fans of inevitability to insist that the ways to succeed as a functioning organism are tightly constrained. Natural selection is thus seen as the biospheric usher, conducting each new aspiring species to an exact seating assignment in a fairly small auditorium. This scenario, however, strains belief. Did the marsupial mole really need to look exactly like the placental mole to satisfy environmental constraints (McMenamin 1998)? Did the Australian thorny dragon lizard (Moloch horridus; agamid lizard family) and the regal horned lizard (Phrynosoma solare; iguanid group) really need to be so similar, right down to the patterning and spacing of the individual dermal thorns (Hutchins 1987)? These similarities seem almost platonic, as in some evolutionary response to an idealized, ethereal form of the desert horned lizard. Thus, it cannot merely be environmental constraint that sculpts these similar forms, but rather some kind of pattern for form, namely, a morphogenetic pattern. The answer, and this may be considered to be the key and most critical statement of this book and its central thesis, may be stated as the first law of morphogenetic evolution: THE SAME FORCES THAT CONTROL MACROEVOLUTION CONTROL THE OBSERVED HIGH PRECISION OF CONVERGENT EVOLUTION. BOTH PROCESSES ARE ASSOCIATED WITH TRANSFORMATIONS OF MORPHOGENETIC FIELDS. The thorny dragon lizard and the regal horned lizard nicely demonstrate this principle of evolution by field morphogenesis. The tips of the thorns ornamenting the skin of these two similar but unrelated lizards may in fact trace the morphogenetic field lines. Natural selection may play a role in determining whether or not a particular new variant survives. Lizards that are spiky, or look just like desert plants, will indeed have an enhanced chance for survival. It is possible, however, that the morphogenetic transform generates a creature that is already adapted to its environment? Then there would be nothing to select. If morphogenetic transformation is in any sense directed, then natural selection is entirely out of the picture with regard to generating the body form in the first place. In any case, natural selection is impotent when it comes to generating biological novelty. Adding to the woes for natural selection, the process now seems inadequate to explain long‐term changes in populations. This has led Jerry Fodor to baldly state that nobody knows how evolution works (Fodor and Piatelli‐Palmarini 2010). Fodor argued at his Pearl Harbor day lecture on December 7, 2009, University of Delaware, that the Neo‐Darwinian account of evolution is based on the fallacious inference from “creatures with such and such a trait are selected” to “creatures are selected for having such and such a trait”. In other words, “creatures with adaptive traits are selected” is not the same as “creatures are selected for their adaptive traits.” In a hotly controversial 2007 article in the London Review of Books, Fodor (2007) notes that there are two halves to the Darwinian synthesis, the shared phylogeny half (true) and the adaptationistic half (involving natural selection; likely false). This is a dichotomy that resembles Stephen Jay Gould’s distinction between the geological concepts of methodological uniformitarianism (true and correct) and substantive uniformitarianism (a false extrapolation, incorrect because it denies the earth a history). With methodological uniformitarianism, ripple marks that formed a billion years ago formed in precisely the same way that stream ripples form today. Geologists use this inference every day, as in, “The present is the key to the past.” With substantive uniformitarianism, as promoted by Charles Lyell in the 1830s, all change on the earth is gradual, slow, and the major events repeat in an endless cycle. Thus, the earth has no real 8 history. Lyell expected to find fossils of mammals and even of humans in Paleozoic strata. When climate cycles back to its Mesozoic state, the dinosaurs and pterosaurs will return. We now are reasonably certain that this will not happen, and that substantive uniformitarianism is therefore wrong. According to Fodor (2007), “In principle at least, it could turn out that there are indeed baboons [sic] in our family tree, but that natural selection isn’t how they got there.” And further: “Darwinists have been known to say that adaptation is the best idea that anybody has ever had. It would be a good joke if the best idea that anybody has ever had turned out not to be true.” Further still: “So, in principle at least, there’s an alternative to Darwin’s idea that phenotypes ‘carry implicit information about’ the environments in which they evolve: namely, that they carry implicit information about the endogenous structure of the creatures whose phenotypes they are.” Fodor links this endogenous‐genesis idea to ‘evolutionary‐development theory,’ or evo‐devo for short. More significantly, however, Fodor here gives a powerful boost to the proponents of biological structuralism, the idea that the structure of whole organisms (not just their genetic codes) is significant, and really needs to be understood in order to understand evolution. Finally, “It is, in short, an entirely empirical question to what extent exogenous variables are what shape phenotypes; and it’s entirely possible that adaptationism is the wrong answer” (Fodor, 2007). To summarize, traits don’t get selected “at all,” rather, it is the “creatures that have the traits” (or whole phenotypes) that get selected. He puts the problem another way as: “keys solve the problem of finding something to open locks, not that locks solve the problem of finding something to be opened by keys.” Or, as Fodor has said, “Contrary to Darwinism, the theory of natural selection can’t explain the distribution of phenotypic traits in biological populations.” And, adaptationist “explanations are species of historical narratives.” There is rich irony here, as Fodor proclaims himself atheist. I find it most amusing, as a Roman Catholic, that atheist Fodor’s intriguing critique of natural selection threatens to destroy the primary article of faith of the atheist religion, that is, a scientistic, materialistic faith in evolution by natural selection. In an action reminiscent of Stalin destroying Hitler, God once again works in mysterious ways. A further irony is that Fodor claims to have initially set out to critique evolutionary psychology, and in doing so noticed systemic weaknesses in evolutionary theory as currently defined. As he said in sharp reply to letters written in response to his 2007 piece in London Review of Books: [Thomas Kuhn] “remarks that you can often guess when a scientific paradigm is ripe for a revolution: it’s when people from outside start to stick their noses in.” This is not the first time that a philosopher has weighed in on an evolutionary topic; it was Henri Bergson who was first to suggest the importance of predators for the Cambrian evolutionary event (McMenamin 1998). If Fodor’s inferences about adaptationism and natural selection are correct, then currently unknown internal factors in organisms could ultimately be responsible for major steps in evolution. The purpose of this book is to discover these internal factors as a means to improve our understanding of evolution. Natural selection has been called the opium of the biologist, because it induces a pleasant departure from the demands of critical thought. In the words of Antonio Lima‐de‐Faria, “nothing could be better than selection because it can ‘explain’ equally well a given situation or its opposite state.” Flaccid thinking abounds among natural selection’s supporters. Richard Dawkins has said that organisms appear to be “brilliantly designed for a purpose . . . [by] natural selection.” Andy Knoll, Harvard’s 9 cheerleader for doctrinaire Neo‐Darwinism, chants that “it’s natural selection every step of the way” (Mazur 2009). But among those who are thinking more carefully about evolution, it seems clear that natural selection is moving from a dominant to a subordinate position in evolutionary thought. Massimo Piatelli‐Palmarini has argued that evolutionary theory dominated by natural selection is “wrong in a way that can’t be fixed.” Fodor has argued for an evolutionary theory without adaptation. This may be too extreme, as I think that we will always be able to refer to selective pressures in ecological analysis. However, natural selection can no longer be invoked to explain big evolutionary jumps, or in other words, the origin of form. In retrospect, with new eyes, this fallacy does actually seem like a pretty risky extrapolation. Darwin invoked his mantra “natura non facit saltum,” “nature does not make big jumps,” as a way of buttressing a theory that requires incremental change for natural selection to be effective. The work of Stuart Newman, with his focus on epigenetic mechanisms for evolutionary change (Newman and Bhat 2008), particularly in the deployment of dynamic patterning modules (DPMs), is beginning to show that indeed “true jumps are possible.” This new saltationalism is really sensational, for as Darwin himself admitted, if there are jumps, “my theory is wrong!” Newman sees the Cambrian explosion as an exploration of morphospace that is decoupled from genotypic change and adaptation. Could this at all be in accord with conventional Neo‐Darwinism, as expressed by paleontologist Bruce Runnegar?: “But ultimately the choice of what survives to the present is competition among components of the biosphere that coexist.” Not really, because the big ‘choices’ are made not by natural selection, but by whatever processes are involved in the genesis of new body form. This brings us to a key question: What are the ultimate sources for evolutionary novelty? There are four ways to answer this question. I am eliminating accumulation of random mutations from consideration, because as I have noted above, this Modern Synthesis idea, as reliant on natural selection, has become obsolete. The first acceptable hypothesis is therefore that Divine Fiat in an act of special creation generates novelty. This concept, especially as applied to the Cambrian explosion, is a mainstay of creationist thought and continues to underwrite their second best argument. It is also closely related to their first best argument, namely, difficulties associated with understanding the origin of life. As argued in Illustra Media’s glitzy 2009 production Darwin’s Dilemma: The Mystery of the Cambrian Fossil Record, the Cambrian explosion was an explosion of biological information, of embryonic blueprints (with assembly instructions in DNA) that directed the development of the first complex life. This information, it is said, is so complex that it points unmistakably to foresight, purpose, and intelligent design of a system that is too complex to evolve. It had to be jump‐started. The DVD for Darwin’s Dilemma includes a reference bibliography and a virtual museum of Cambrian fossils, an admirable catalogue of fact by the Intelligent Designers and a laudable first for creationism. The second way to generate novelty is by symbiogenesis. Championed by Lynn Margulis and her closest colleagues, symbiogenesis is the old Russian concept that radically new types of organisms are created when intimate symbioses become obligate symbioses, and genomes begin to fuse (Khakhina 1992). These rather unchaste mergers, derided by creationists as Lamarckism (as an inheritance of acquired characteristics), actually do 10 occur and are probably responsible for many of the hugest steps in evolution, such as the appearance of the eukaryotic cell several billion years ago. A problem with symbiogenesis, however, it that it does not seem to be of much assistance for explaining the sudden appearance of major animal body plans during the Cambrian explosion. Symbiogenesis may, nevertheless, play a more minor role in explaining the acquisition of Cambrian skeletons, as there is some evidence in stem group brachiopods (Mickwitzia) that internal bacteria secreted their phosphatic skeleton. The third way to generate the required novelty is by self‐organization. Here, the pattern language of DPMs triggers self‐organization during the transition from microbes to mesoscale organisms (Newman and Bhat 2008). As discussed below, this hypothesis can help to explain the Cambrian explosion. The fourth explanation invokes morphogenetic field generators to create body form in an epigenetic fashion. A morphogenetic field is a geometrical pattern or virtual grid framework that somehow guides the development of organisms as they grow. Rapid modulations of a morphogenetic field, similar to, say, reversing the poles in an electromagnet, could conceivably lead to drastic and sudden changes in the morphology of complex organisms. This is just what is needed to, say, explain the Cambrian Explosion. Interestingly, explanations one (Divine fiat), three (self‐organization) and four (morphogenetic fields) are comparably good at explaining the Cambrian Explosion, because they are potentially receptive to discontinuous, abrupt change. Numbers one and tree seem to be mutually exclusive, for how can something both organize itself and be a product of an instantaneous Divine special creation? I am thus eliminating these as the fiat fallacy and the self‐organization fallacy, respectively. This leaves us with the morphogenetic field hypothesis that, interestingly, excludes neither self‐organization (i.e., by invoking DPMs) nor Divine intervention, or even Divine intervention of a rather direct sort. Lest this seem too great a departure from naturalistic science, let’s say that it is time for everyone to wake up to the possibility of God’s action in the world. As Dianna McMenamin says in her critique of Intelligent Design: “God is not a hypothesis.” Complex life, then, appears with the first creature that may be called a Morphogenetic Field Generator (MFG). As soon as Life is breathed into this form, an evolutionary radiation takes place. This is not an adaptive radiation in the traditional sense, but rather, in the Newmanian sense, an exploration of morphospace decoupled from adaptation. This is a unique moment of epigenetic evolution, and not too surprisingly, it initially develops into a Garden of Ediacara. The metastable ecology of the Garden of Ediacara lasts for about 60 million years, after which time it gives way to the Cambrian Explosion itself at about 541 million years ago. MFGs burst forth with sudden new form, generating and animating the Cambrian phyla. Cambrian predators such as Anomalocaris appear on the scene in short order, and modern marine ecology emerges from the remains of the Garden of Ediacara. Being ultimately controlled by morphogenetic field generators, neither the Ediacaran Radiation nor the Cambrian Radiation are influenced in their formative stages by natural selection. What then of doctrinaire Neo‐Darwinian evolution by natural selection? Is natural selection still part of the evolution conceptual package? May we still speak of adaptive radiations, and even adaptive superiority, in the sense of, say placental mammals that are able to outcompete marsupial mammals that in turn are able to outcompete monotreme mammals? The short answer is no. The primary role that natural selection once played in 11 evolutionary theory is gone forever, and thus relatively short term competitive advantages between various groups can no longer be used neither to explain macroevolution nor to underwrite racist theories of dominance. It is important to remember that an archosaur group (dinosaurs) suppressed all mammals until the Cretaceous‐Tertiary mass extinction. How ironic that dinosaurs were until fairly recently sometimes portrayed as lumbering, reptilian evolutionary failures. No more is the fall of natural selection more evident than in the genesis of new body form. Charles Darwin, in a characteristic, brutally direct statement, once said that if “it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.” The crumbling edifice is inducing a kind of temporary schizophrenia among evolutionary biologists and paleontologists with vested interest in perpetuating the reign of natural selection, for nationalistic or other reasons. For example, Simon Conway Morris (2009) argues, with regard to the Cambrian explosion, that the “observed transformations happen quickly, but they are not saltational.” This is quite curious—in my lexicon ‘quickly’ and ‘suddenly’ are near synonyms. Conway Morris goes on to affirm, quite unconvincingly, that the Cambrian event proceeds by “comfortably . . . familiar microevolutionary mechanisms [with] no macroevolutionary jumps.” Curious again, for why then do we call it the Cambrian explosion and why is it generating so much debate? In an event comparable to vertebrate paleontologist Kevin Padian hanging up on Suzan Mazur (2009), Simon Conway Morris has been curiously silent about the work of Chris Venditti, Mark Pagel and others (Venditti et al. 2009). This work suggests that natural selection may not be the cause of speciation. Pagel (Edwards 2009) notes, regarding this work, that it “really goes against the grain” for scientists with an investment in the collapsing Darwinian paradigm. Indeed, I think that what we see here is a scientist out of his comfort zone. This speaks to an inability on the part of Simon Conway Morris (2009a, 2009b) to come to grips with the real implications of the fall of natural selection, and the real import of a bright new post‐Darwinian world. In what may be a case of “Brittania non facit saltum,” Conway Morris sees the configuration of the Tree of Life as a “pre‐determined” template of evolutionary bifurcations that is filled in, with all the expected convergences, exclusively by conventional microevolutionary processes. Conway Morris (2009b) is concerned about being labeled a Darwinian heretic, so he clings to microevolutionary gradualism in an attempt to maintain a façade of at least partial Darwinian orthodoxy. Conway Morris’ static and fixed template, however, cannot explain the rapid burst of evolutionary creativity at the Cambrian. We must seek better explanations. The place to start is by examining the organisms themselves, particularly from the perspective of what Vorobyeva (2003) calls their “common latent morphogenetic potentialities.” 12 Chapter 1: Paleontology and Morphogenetic Fields A MORPHOGENETIC field is a mathematical pattern or virtual grid framework that somehow guides the development of organisms as they grow. Needham (1950) defined morphogenetic fields as a “system of order such that the positions taken up by unstable entities in one part of the system bear a definite relation to the position taken up by other unstable entities in other parts of the system.” The study of morphogenetic fields is an accepted but currently rather neglected part of conventional biology. In fact, the theory of morphogenetic fields has had a very rough time for the last half century in biological circles. Opitz (1985) went so far as to say that the concept seems “to have simply vanished from the intellectual” heritage of Western biology. Various types of field theories have been tried in biology, some of them with inappropriately vitalistic and/or parapsychological overtones that have more than upset conventionally‐oriented scientists. The concept of the morphogenetic field indeed is an important part of our scientific patrimony (Gilbert 2006). This has been the case since even before H. Driesch pulled apart a sea urchin embryo at the four‐cell stage and was able to grow an entire larva from the isolated cell or blastomere (Driesch 1908). Driesch used the phrase “harmonious equipotential system” which today we would translate as “morphogenetic field.” After reading his work, E. Haeckel recommended that Driesch check himself into a mental institution (Oppenheimer 1967), and Gould (1977) evidently seconded the motion. Driesch’s work, however, has much to recommend it, and it may be time now to seriously reconsider his work (McMenamin 1998), particularly that part of his opus relating to morphogenetic fields. Of particular interest is the relationship between morphogenetic field theory and genetic modularity theory as described by Rudolf A. Raff (1996:324), where he asks, and “Can the events of the Cambrian radiation be played out in a vial of fruit files?” What place should morphogenetic field analysis have in the sciences? Raff (1996) and others are prepared to take morphogenetic fields very seriously. I suspect that its importance will ultimately prove to be great, and that important new laws of development will proceed from our attempts to gain insight into the significance of morphogenetic fields. Pivar (2004, 2009) has defined a concept of biological structuralism based on evolutionary changes associated with the Multi‐Torus (Jockusch and Dress 2003), a toroidal balloon with a bend in it, a kind of developmental smoke ring in motion. This biological structuralism has been criticized (Bob Hazen in Mazur, 2008) for both a paucity of new data and for lacking rigorous mathematical backing. These criticisms, however, are weakening as new data accumulate. This book aims to address both deficiencies by evaluating Multi‐Torus or Morphogenetic Torus Theory using the fossil record. First will be description of and 13 discussion one of most recently recognized members of the Ediacaran biota, a fossil that looks astonishingly like a fossilized morphogenetic torus. Next we will evaluate a newly discovered giant trilobite with characteristics that seem to support toroidal morphogenesis theory. Then we will look at an application of the model to scleritome theory (i.e., the theory of shell evolution) and to the Cambrian origin of mollusks and brachiopods, and as a result will develop a new and powerful dual application of torus‐scleritome theory. Next we will focus in on the early development of cephalopods and a new variant of the torus called hypertorus. Finally, we will consider a counterexample to toroidal morphogenesis in the growth of marine microbes known as foraminifera. Using an exciting, newly discovered foraminiferal microbiota (that turns out to be exactly contemporary with the new giant trilobite), we will explore the metacellular/chambering style of morphogenesis that stands in contrast to toroidal morphogenesis as a parallel morphogenetic system. Figure 1.1 shows a textile model of part of the torus, what I will call here the Torus Cap. 13‐year old Jessica McMenamin models the cap. Her personal torus, by the way, would reach its anterior pole at her deuterostome oral opening (mouth). Figure 1.1. The Torus Cap. The peak of the cap models one pole of the torus, and the blue bands and ellipsoidal lumps model a morphogenetic grid. An orthogonal grid representing a morphogenetic field is delineated by the light blue and dark blue banding (transverse or germ bands) and light blue and dark blue lumps, respectively, representing torus axis parallel bands. 14 The torus cap models the latitudinal or transverse grids of the toroidal morphogenetic field, as shown with the alternation of light blue and dark blue stripes as shown in Figure 1.1. The cap also models the longitudinal grid work of the toroidal morphogenetic field, shown here as the regular lumps or ellipsoidal swellings that ornament the cap. Together, the lumps and the bands simulate the torus field in a way that will be useful for orientation as we discuss the evolutionary implications of the morphogenetic field. Marine invertebrate fossils of the Ordovician Period (489‐443 million years ago), including trilobites, nautiloids, gastropods, and foraminifera will play important roles as we proceed on our journey through the torus. The new discoveries reported here are paleontologically quite exciting, and involve several rather fortunate finds from Ordovician rocks both east and west of the Mississippi in North America. Occasional technical terms are used in this text to describe fossils and fossil morphology. Instead of printing a glossary to define these terms, I urge you dear reader to go online and use Google to look up any terms that seem unfamiliar. In many cases Google Images will provide you with several illustrations as well. Try it now, if you wish, on the term for the tail region of a trilobite: pygidium. Toroid morphogenesis promises to open up a whole new approach to paleontology. Numerous new questions arise with this new perspective. The Early Cambrian echinoderm Helicoplacus, soon to be discussed, looks like a twisted football. To what extent is Helicoplacus influenced by toroidal development? To what extent is its unique shape controlled by a toroidal (or otherwise) morphogenetic field? Archeocyaths are unusual cup‐shaped organisms with calcareous skeletons that are characteristic of shallow marine limestones deposited during the Lower Cambrian. Some researchers have suggested that they are closely allied to the sponges but whether or not the similarities are due to convergent evolution is not entirely clear. Archeocyaths undergo a dramatic evolutionary radiation during the Lower Cambrian. This is one of, if not the, strangest radiations in the entire fossil record. More explosive than the Cambrian Explosion of which it is a part, archeocyaths appear in the Tommotian stage of the Lower Cambrian, expand in the Atdabanian stage, expand in diversity to hundreds of genera by the Botomian stage (which could be called the Age of Archeocyaths), and then crash in diversity in the subsequent Toyonian stage, the final stage of the Lower Cambrian. This boom in diversity near the base of the Cambrian, and equally dramatic drop in diversity near the Lower to Middle Cambrian transition, is unprecedented in the fossil record. A few atypical archeocyaths survived until the Upper Cambrian in Antarctica. Archeocyaths are responsible for the oldest skeletal reefs. The archeocyath radiation represents morphogenetic field transformations in fast forward, spinning out new varieties in an exuberance of form in an intense cameo microcosm of the Cambrian explosion itself. The archeocyath body has a hollow central cavity that is surrounded by inner and outer skeletal walls. After the initial growth stages, these walls are porous. The space between the walls is filled with rather regular septa, as in regular archeocyaths, or by 15 rather irregular (but still often geometrically arranged) taeniae. As such, they resemble the lower half of the mathematically defined Horn Torus, horn‐shaped as its name suggests. A toroidal origin for sponges seems quite reasonable if as has been recently suggested, simple animals like sponges and more complex animals share common ancestry through the placozoan animal Trichoplax. In a subsequent chapter we will discuss poriferan departures from horn torus morphogenesis. The porosity of archeocyath cups is one of their most striking characteristics. This porosity is so extreme in some genera that inner and outer walls, septa, and tabulae appear as spindly frameworks not unlike the geometrical framing which supports the windowpanes in an old‐fashioned greenhouse. Figure 1.2. Archeocyaths from Nevada. The fossils are seen as transverse cross‐sections of the archeocyath cup. At least three genera of archeocyaths are present. The three specimens closest to the center of the photograph (Ethmophyllum sp.) show complexly porous ethmophyllid‐like inner walls, an important character that has appeared multiple times in unrelated lineages over the course of archeocyath evolution. Stylolites (limestone dissolution layers) cut across several of the archeocyath cups. Sample MM‐85‐4; Poleta Formation, Barrel Springs, Nevada. Scale bar in centimeters. We must now ask the question: Is the overall shape and geometric porosity of archeocyaths somehow related to a horn toroidal morphogenetic field? A number of archeocyath genera and species would seem to support the notion that a morphogenetic 16 field is at work in construction of the Cambrian archeocyath cup or horn torus and its modifications (Debrenne and Zhuravlev 1992). The geometrical pores or syrinx facets of Syringocnema and Pseudosyringocnema look like three‐dimensional nets that seemingly resemble the Fresnel diffraction pattern. The tabular structure of Dictyosycon sp. from the Asiatic Altay Sayan Fold Belt looks like a crystal model showing bonds between atoms. The flattened Okulitchicyathus discoformis looks like a pancake with its concentric field markings, resembling part of the biconvex electrostatic field lines of electron diffraction experiments. Strangest of all, however, is the inner wall structure of the archeocyath Tercyathus altaicus Vologdin from the Sanashtykgol Suite of Sayan. The structure looks as much like a nonlinear chemical oscillator such as one resulting from the Belousov‐Zhabotinsky reaction as it does any biological structure (Vologdin 1957). Clearly, morphogenesis here is being controlled by system wide rules of morphogenesis or perhaps some sort of chemokinesis or chemotaxis, or both (Newman and Bhat 2008). Bizarre exothecal growths of archeocyaths, in spite of their apparently adventitious character, also seem to be developed under the influence of a morphogenetic field (Debrenne and Zhuravlev 1992). Ardrossacyathus endotheca from the Yorke Peninsula of South Australia has an exterior growth that looks like the morphogenetic field lines of a bizarre three‐dimensional fingerprint. Finally, morphogenetic torus evolution theory may also open up new horizons in paleobotany. Cubtail mosses, and especially their giant Paleozoic versions the arborescent lycophytes, have leaf scar or leaf cushion pattern that looks very geometrically regular. This pattern could be simply the result of apical growth at the stem tip, but other explanations involving the influence of morphogenetic fields may also be possible. Sphenophyte (horsetail) stem anatomy has a structure that is not unlike that shown by Stuart Pivar (2009) in his first seven stages of flower morphogenesis. This model requires careful analysis to determine whether the resemblances are superficial or otherwise. Of potentially even greater interest for applications to paleobotany is the case of early plants belonging to a group known as the zosterophylls. Zosterophylls, known from Lower to Middle Devonian terrestrial strata, have been found in the famous Rhynie Chert deposit in Scotland and have also been found in South America. The curious thing about these plants is that they are bilaterally symmetric. Have a look at the zosterophyll specimen of Rebuchia ovata, from the Early Devonian of Beartooth Butte, Wyoming, currently on display at the National Museum of Natural History in Washington, D.C., and you will see that the extinct zosterophylls really were bilaterally symmetric. This is a rather unusual constraint for vascular plant form, and constitutes pretty strong evidence that morphogenetic fields (and perhaps even toroidal morphogenetic fields, considering the bilateral symmetry in zosterophylls) have or at least had a significant role to play in vascular plant development. Control of morphogenesis has been recently demonstrated by experimental manipulation of a morphogenetic field in Arabidopsis by means of oryzalin treatment (Hamant et al. 2008). Other factors, such as incremental geometric growth or phyllotaxis as seen in a sunflower head, can of course also influence plant morphology. We can now begin to elucidate a new law of evolutionary morphogenesis. Note how the influence of morphogenetic fields is most obvious in the earlier members of any 17 particular major group of complex multicellular organisms. Bilateral zosterophyll plants, archeocyaths with their network skeletons, spiral helicoplacoid echinoderms (Figure 1.3; McMenamin 1987), geometrically punctate mickwitziid brachiopods (McMenamin 1992), myomeres in the Cambrian chordate Pikaia from the Burgess Shale or Myllokunmingia from China, and the Ediacaran fossil described in the next chapter all show marked morphological evidence for morphogenetic fields. The second law of morphogenetic evolution may thus be stated as follows: EVIDENCE FOR DEVELOPMENTAL CONTROL BY MORPHOGENETIC FIELDS IS MOST APPARENT IN THE EARLIEST REPRESENTATIVES OF ANY PARTICULAR LINEAGE OF COMPLEX LIFE. This new law makes it quite clear that it is pretty ridiculous to try to conduct any kind of morphological analysis in biology without full consideration of the empirical data from paleontology. It would be equally absurd to try to conduct the study of biological form in the absence of careful analysis of the influence of any and all associated morphogenetic fields. 18 Figure 1.3. Helicoplacus gilberti Durham and Caster 1963. Middle Poleta shale, Blanco Mountain Quadrangle area, White‐Inyo Mountains, California. This spectacular specimen shows a helicoplacoid spindle body on its side, with a slight tear at the apex revealing the spiral deployment of echinoderm plates. Note the roughly orthogonal placement of platelet rows and columns. This may represent, in slightly modified form, a fossilized morphogenetic field in the form of a slightly twisted torus. This would be a modified torus, however, as current research suggests that the mouth of the animal is at the side of the spindle rather than at one of the ends, although, it should be noted, that the position of the mouth of Helicoplacus has not been identified with absolute certainty. Sample MM‐85‐7(1); McMenamin collection. Centimeter scale bar. 19 Chapter 2: An Ediacaran Toroid from Namibia THE AUS PLATEAU of Namibia has yielded spectacular Ediacaran fossils ever since pioneering German scientists first discovered the site around 1908 in what was at the time colonial South West Africa. Namibia provides the type locality for both Pteridinium and Rangea, two of the most important and best‐known Ediacarans from localities outside of Australia (Vickers‐Rich 2008). Ediacaran fossils are notoriously difficult to classify with regard to phylum or even kingdom. For example, the famous German paleontologist Adolf “Dolf” Seilacher has had his difficulties with interpretations of the Ediacaran fossils Mawsonites, “Oldhamia” recta, and Vermiforma antiqua. In the first two cases, Seilacher classified the specimens as trace fossils when in fact they are body fossils, and in the latter case he classified as a pseudofossil what is in fact a trace fossil. This merely testifies to the difficulty of the task at hand, as Seilacher is considered by many to be the finest living paleontologist. During an expedition to Namibia in 1993 led by Seilacher, a slab containing numerous specimens of Pteridinium was excavated and cast in silicon (McMenamin 1998). Images of this slab have appeared on the cover of Science magazine and in a Scientific American October 1994 article by Stephen Jay Gould. The slab is covered by a variety of Pteridinium specimens in a bewildering pattern of orientations. Some of the specimens appear to be undeformed, whereas others seem to be distended or stretched. It is not entirely clear whether the Pteridinium specimens lived within the sediment or on top of it, and both hypotheses have their supporters (Grazhdankin and Seilacher 2005; Crimes and Fedonkin 1996). An unusual specimen appears on the Seilacher Slab amidst the other Ediacarans. At first I thought that it might be a deformed Pteridinium, but it lacks the midline that we would ordinarily expect to see as part of the bizarre tri‐fold Pteridinium body form. My analysis of the morphology of this fossil shows that it is in fact a fossilized and flattened metazoan torus. Figure 2.1 shows the fossil, preserved as an external mold hyporelief on the base of a sandstone bed. In the description that immediately follows I plan to intentionally mix observations with interpretations to give you a sense of the creature as I interpret it. A more formal description, with interpretations clearly set to one side, will follow with the systematic description of the new taxon. 20 Figure 2.1. Vendoglossa tuberculata Seilacher, 2007. Cast of fossil in fiberglass painted and stained to enhance the contrast. Original specimen held in the H. Erni Collection, Namibia. Scale bar in centimeters. The fossil is indeed tongue‐shaped, and tapers to a bluntly pointed end. More than 25 segment‐like striations are seen perpendicular to the long axis of the fossil. Instead of a midline as in Pteridinium, the fossil shows a pair of ridges that delineate the central third of the body, approximately the same position as occupied by the axial lobe of a trilobite. But in a major departure from trilobite morphology, no appendages of any kind appear. Instead, we see that the medial ridges are inclined toward the midline of the fossil; in other words, they dip away from the sides of the organism like the limbs of a geological syncline. In fact, these ridges represent the impression of the inner part of the torus showing through the outer toroidal surface, in this particular case the underside of the organism. The central cavity thus defined appears to be nearly closed off to the exterior at the preserved, blunt termination of the fossil, interpreted here as the mouth or anterior end of the torus. This interpretation is based on the fact that there is a slight dimple just posterior of the true anterior end of the animal, and this dimple might represent the throat cavity of a detritus feeding metazoan. There is, however, no evidence for sediment accumulation within the gut of the animal, and furthermore evidence exists (see below) that the gut cavity was at least periodically exposed to open sea water as might be the case for a filter feeding organism or for an animal feeding by means of photosymbiosis or chemosymbiosis. Nematodes, the phylum to which this new fossil organism may belong, are known to have marine chemosymbiotic members (Polz et al. 1994). There is no evidence, however, for any type of efficient filter feeding apparatus either within or on the 21 outside of the organism, so perhaps the latter feeding strategy (photosymbiosis) may be assumed for this shallow water marine organism. This specimen therefore represents the metazoan ur‐torus. It is in essence a fossil in hyporelief of the theoretical construct illustrated by Pivar (2004) as the toroidal membrane (Figure 2.2). Figure 2.2. A computer generated image of Vendoglossa tuberculata Seilacher, 2007 as a toroidal membrane, modified from Jülicher (1993) and Pivar (2004). Note the convergence of longitudinal lines near the poles. If the interpretation presented here is correct, the match is nothing less than astonishing. The latitudinal bands as shown in Figure 2.2 are mimicked by the transverse, segment‐like striations. The toroid interior or gut cavity is constricted at both ends, just as in the toroidal membrane shown in Figure 2.2. The only topological difference of any significance is the fact that the long axis of the fossil is comparatively longer than in the model toroidal membrane as shown in Figure 2.2. Also, the animal may have been dorso‐ventrally compressed, but it is hard at this stage to know exactly to what degree this was the case considering that sediment compaction may have occurred during the process of deposition and fossilization. As the specimen is preserved in a medium‐grained sandstone deposit, the degree of compaction would be expected to be less than in, say, a fossil that was preserved in shale or mudstone. The fossil was recently named Vendoglossa tuberculata Seilacher, 2007. As is the case for most Ediacaran fossils, some uncertainty is associated with the exact mode of 22 preservation of this fossil. The animal appears to have been entirely soft‐bodied, and yet it forms a high‐fidelity impression in a relatively coarse clastic sediment deposit. James Gehling (Gehling 1999) and others, following up on suggestions made by Seilacher in the 1980s, have suggested that soft‐bodied Ediacarans were preserved as a result of mineralization due to a thin microbial coating on the surface of the Ediacaran corpse. This coating or death‐mask rendered the outer surface of the nascent fossil resistant to crushing. McMenamin (2004) has criticized the death mask model for failing to account for superimposed Ediacaran fossil impressions, as in cases where one fossil had fallen on top of another, allowing no space for the preservation‐critical microbial film to form. Vendoglossa tuberculata adds important new information to the death mask debate, for some type of hardening agent influenced the interior of this organism to enable preservation of the walls of the torus interior (presumed gut cavity). If we assume that the gut cavity was open to sea water, a reasonable assumption if the animal was photo‐ or chemosymbiotic in the sense of a Garden of Ediacara organism (McMenamin 1998), then the preservation might be due to crystal film hardening by inorganic mineral precipitation directly from sea water to form a mineral crust on both the inside and the outside of the organism. Microbes need not necessarily have been directly involved. Vendoglossa tuberculata is also an important addition to the known morphologies of the Ediacaran biota. Although referring to the vendobiont/petalonamid Ediacarans (the flat ones with metacellular quilted‐pneu structure), Martin Lockley’s (1999) comments could apply to Urtorus nearly as well: “The form of some of Seilacher’s beloved Precambrian organisms is reminiscent of magnetic fields, and reminds us of [the emerging] holistic view of organisms.” This is a prescient statement that anticipates the arguments on morphogenetic fields presented here. We may soon be able to speak in terms of a morphogenetic torus field and a pneu‐quilted field, and how these two interacted to determine the paleoecology of the Proterozoic seafloor. Other explanations for the paleobiology of Vendoglossa tuberculata are also possible, such as the interpretation of the fossil as the remains of a giant microbe, such as for instance a gigantic version of the opalinid ciliate Opalina cheni Nie. Such an interpretation runs into several difficulties, however. First, it is difficult to see how such a large ciliate could respire, considering that its interior was well removed from its anomalously thick outer membrane. With no circulatory organ system, cytoplasmic streaming would be insufficient to satisfy the creature’s need to expel waste. This difficulty might be removed by, say, having a body filled with photosymbionts. The microridges in Opalina cheni Nie run from anterior to posterior, whereas the ridges in Vendoglossa tuberculata run orthogonal to this, that is, transversely across the creature’s body. Helicoplacoid echinoderms have both sets. Thus, all three organisms may be reflecting the geometry of a morphogenetic torus. 23 Chapter 3: Parazoans and Metazoans: Testing the Morphogenesis Model SPONGES HAVE SKELETONS built up of spicules, and special biomineralizing cells called sclerocytes form these spicules. Although there have been unconfirmed reports claiming the occurrence of sponge fossils in Proterozoic strata, the oldest certain sponge fossils are from the Lower Cambrian. One of the earliest of these is the sponge genus Kiwetinokia. The evolution of spicule morphogenesis in the Cambrian sponge genus Kiwetinokia represents a departure from the dynamic control of Cambrian morphogenesis by morphogenetic fields. The expression of cell‐cell adhesion (ADH/DAD) dynamical patterning module (DPM) effects decreased over time in the Kiwetinokia lineage. It was evidently expedient to do so in a Cambrian biosphere that favored filter and suspension feeders utilizing a mesenchymal body plan; curiously, natural selection in this case seems to be a cause for a devolution, rather than synthesis of a major new complex animal body plan. This result is consistent with indications that sponges derive from a metazoan ancestor bearing the developmental toolkit for complex tissue grade multicellularity, and that this ancestral form was also the common ancestor of bilaterians. Recent results suggest that a primitive metazoan called Trichoplax may have been the common ancestor for all animals (Schierwater et al. 2009). This further suggests that bilaterian animals and diploblast animals (such as jellyfish) separated early on, and that they independently evolved complex body plans, body axis types, nervous systems, and sensory organs using the same basic genetic tool kit found in the common ancestor. Cell‐cell adhesion dynamic patterning modules are essential for animalian multicellularity (Newman et al. 2009; Newman et al. 2008). Cadherins (a major class of membrane proteins) execute the cell‐cell adhesion dynamical patterning module (DPM), a dual module that consists of ADH (adhesion) and DAD (differential adhesion) effects. 24 Figure 3.1. Kiwetinokia sp. Several twisted and fused spicules are visible. Early Cambrian. Lower Unit 3, Puerto Blanco Formation, Cerro Clemente, Sonora, Mexico, 1 of 12/15/82. Figure 3.2. Kiwetinokia sp. Enlargement of the twisted spicule cluster (3) seen in previous figure. 25 Figures 3.1‐3.2 show the earliest known representative (Botomian Age, Early Cambrian) of the sponge genus Kiwetinokia. It belongs to a group known as the protosponges. The specimen shows twisted spicule morphology (McMenamin 2008). Continuous cell motion characterizes modern sponge morphogenesis (Bond 1992). In Kiwetinokia sp., spicular twisting indicates that the sclerocytes responsible for each spicular strand adhered to, and simultaneously twisted around, neighbor sclerocytes in clusters of two, three or even more cells to form the spiraling spicular bundle. Later Cambrian species of Kiwetinokia (such as Middle Cambrian Kiwetinokia spiralis) also show twisted spicules, but the bundles have fewer strands, involving only a single pair of sclerocytes (McMenamin 2008). This implies that over the course of the Early Cambrian, the genus Kiwetinokia reduced its expression of ADH and DAD DPMs in several species‐level phylogenetic steps on a trajectory leading away from complex tissue‐grade multicellularity. In other words, these sponges underwent a rebellion against overall somatic control by morphogenetic fields that in some ways is comparable to carcinogenesis. A particular morphogenetic field was present at each step (that is, each new species), and influenced the geometric positioning of spicules within the sponge body. But the degree of integration was much less than in a typical metazoan. This somatic disintegration reaches its greatest expression in the glass (hexactinellid) sponges. These sponges lose individual cell membranes and become syncitial, with cell nuclei swarming in a mass of cytoplasm. The syncitial habit, more characteristic of amorphous organisms such as slime molds, is very unusual for animals. The evolution of spicule morphogenesis in Kiwetinokia represents a phylogenetic analogue to the epithelial‐mesenchymal transformation (EMT) known in cnidarians (jellyfish and their kin) and triploblastic bilaterians (Newman et al. 2008; Newman et al. 2009). Reliance on the ADH/DAD dynamical patterning module was reduced in a departure from the primarily epithelial format of Trichoplax‐type organisms. Kiwetinokia simultaneously amplified its reliance on the extracellular matrix (ECM) dynamical patterning module, thus constituting a shift to a body plan with an increasingly mesenchymal format. Modern sponges are thoroughly mesenchymal organisms that depend heavily on the ECM . This inference of an epithelial to mesenchymal body transformation gains credence from the fact that sponges have homologues of basement membrane type IV collagen (Boute et al. 1996; Nichols et al. 2006) and epithelial cells (Schröder 2004), which both thereby take on a vestigial aspect in sponges. This is in accordance with the hypothesis that parazoans (sponges) and metazoans (all other animals) share a common animalian ancestor that had epithelial cells, basement membrane type IV collagen, and cell‐cell adhesion DPMs. Kiwetinokia eliminated rigid cell‐cell adhesion dynamical patterning module effects through the Cambrian, in essence unknotting its morphogenetic field, even as such effects were elaborated along with other DPMs in bilaterally symmetric, complex animals such as trilobites (McMenamin and McMenamin 2001; Newman et al., 2008; Newman et al. 2009). Parazoan animals (such as sponges) should be seen as highly successful variations on “ur‐metazoan” morphogenesis, optimized for suspension and filter feeding in a Cambrian marine biosphere that favored such feeding strategies. Sponges subsequently reduced the epithelial format of their body plan even further by introducing 26 intracellular spicule formation within epithelial cells (Maldonado and Riesgo 2007). The sponge morphotype has fewer morphogenetic possibilities than essentially epithelial organisms like cnidaria (jellyfish and corals), or than the triploblastic bilaterians, which owe their morphological complexity to organization of epithelial and mesenchymal tissues by morphogenetic field patterning. The hypothesis presented in this chapter is the idea that sponges represent a radical modification of morphogenetic field control of body form. Archeocyaths, on the other hand, represent animals at or near the sponge (parazoan) grade of organization that submitted to developmental control by a still largely toroidal morphogenetic field. The riot of new archeocyath species and genus level evolution in the Early Cambrian represents an internal battle (endogenous conflict) between a metazoan morphogenetic field and a less‐structured parazoan morphogenetic field. This evolutionary event deserves its reputation as the greatest “boom!” of the Cambrian Explosion. The conflict is expressed in the archeocyath body form as a cup and wall structure that is geometrical in the extreme, versus the exothecal, adventitious growths that occasionally form on archeocyaths. These are disorganized and more typical of, say, encrusting sponges. This morphogenetic dissonance leads to a feedback in archeocyath morphology, and generates species production willy‐nilly. It is as if the “generate species” knob is stuck on fast forward, producing in short order a literally kaleidoscopic explosion of archeocyath body form that lasts until an extinction event later in the Cambrian. The extinction resets the system back to ‘normal’. Of all the paleontological examples presented in this book, this one (plus helicoplacoid morphology) is the most injurious to the concept of gradualistic evolution by natural selection. Once again, I present here the idea that sponges represent a radical modification of morphogenetic field control of body form. As such, this represents a potential test of the second law of morphogenetic evolution: EVIDENCE FOR DEVELOPMENTAL CONTROL BY MORPHOGENETIC FIELDS IS MOST APPARENT IN THE EARLIEST REPRESENTATIVES OF ANY PARTICULAR LINEAGE OF COMPLEX LIFE. For if, contrary to the opinion expressed here, sponges are the ancestors of other animals, (in other words, if parazoa are ancestral to metazoa rather than the other way around), then the second law is falsified and the views regarding morphogenesis presented here will have to be reconsidered. 27 Chapter 4: A New Giant Trilobite PIVAR (2004, 2009) interprets trilobites as derived from an ur‐toroidal ancestor. If we accept this derivation as a working model, and indeed it has a certain amount of credibility considering the new Ediacaran fossil Urtorus described above, then we may consider how modifications of a toroidal morphogenetic field might help to explain the morphology of certain trilobites. The currently largest known trilobites (Rudkin et al. 2003; 700 mm length; but competition for the size championship may soon be forthcoming from new discoveries in Portugal) belong to the Ordovician genus Isotelus rex (the name is of course a play on Tyrannosaurus rex), a trilobite that rather strongly resembles stage four of five in the ontogenetic‐phylogenetic series illustrated by Pivar (2004). It might be argued that, on the contrary, Isotelus, with its relatively small number of pleural (thoracic) segments is in fact derived from earlier Cambrian trilobites that had more and in some cases many more pleurae. This is in fact the case, and the loss of segments in Isotelus would be seen as part and parcel of the reduction of parts seen in many arthropod lineages, often resulting from either outright loss, or by fusion of once independent segments by a process known as tagmosis. Here, however, we begin to see the inadequacies of a conventional Darwinian evolutionism that focuses too intently on the process of natural selection and consequent pan‐selectionistic evolutionary pressures. Note how, in the isotelid trilobites, the cephalon (head) and pygidium (tail shield) are precisely the same shape. There might very well be an adaptive explanation for this. Trilobites were subjected to a rather vicious form of selection due to predatory attack by newly evolved, voracious cephalopods with a taste for trilobite flesh. These Ordovician nautiloids, some of which grew shells reaching an astonishing 5 meters in length, forced trilobites to enhance their protective behaviors and morphologies. A favorite trilobite defensive strategy was to enroll, in other words, to roll up like a pill bug or sow bug. This particular behavior was rare before the Cambrian but quite common afterwards. Naturally, the roll up defense is more effective if, once enrolled, your body can make a perfectly smooth ball. Hence the match between the cephalon and pygidium in Isotelus has considerable defense value. But rather than being a step by step process of slow selection favoring trilobites with increasingly tighter fit between heads and tails (the classic selectionistic story of evolutionary optimization), the problem was probably solved for Isotelus in something resembling a single evolutionary step. In an atavistic 28 heterochronic development, the carapace of early isotelids changed to conform more closely to the ur‐toroidal shape. The cephalon and pygidium were thus automatically rendered a nearly exact fit, because symmetrical ends of the morphogenetic torus molded the shape of both. This is an extremely important point, for it impinges directly on our understanding of the evolutionary process. For Darwinian evolutionists, there has to be a more or less randomly generated series of overbite trilobites that don’t match up very well when they try to roll. Cephalopods easily munched on the mismatched misfits. The few lucky trilobites with a good fit are harder to eat because of their smoother rolled surface that protects all of their soft insides; hence they survive and leave more prodigies, or rather, progeny. This is a fallacious just so story, and is rightly criticized by foes of evolution. It puts the selective carriage before the morphogenetic horse. Natural selection has a role to play, to be sure, but it is in editing out toroid mismatches after the toroidal cephalic‐pygidial fit is already more or less established. And herein lies the great strength of Pivar’s (2004) biological structuralism. Genes exist, yes, natural selection could conceivably occur after the fact, yes, but it is the response to constraints of, in this case, the toroidal membrane that really generates animal shape. We can take this further. Much further. The enrollment reflex itself might be due to a tendency for an elongate torus to kink, as seen in Pivar (2009). And in regard to elongation of the torus, we may begin to discuss enigmatic groups of early Paleozoic trilobites that are extremely long. These are known as olenimorph trilobites, named for the eponymous trilobite genus Olenus that developed this peculiar morphology (Fortey 2000). An estate sale in early 2007 led to auction of a relatively large trilobite fossil from an old estate in Essex County, Virginia (the online auctioneer was based in Fredericksburg, Virginia). This specimen is shown in Figure 4.1. 29 Figure 4.1. The giant olenimorph trilobite Torolenimorpha longa n. g. n. sp. from the Effna Formation of Virginia. Note the trilobed body characteristic for trilobites. A rounded glabella is visible on the right edge of the specimen. Sample 1 of 4/11/08. Scale bar in centimeters. The specimen has slight abrasion, scratches, and red flecks on its surface, as if it had spent some time stored rather casually in what might have been a children’s colored pencil or crayon box. The original estate collection included other fossils, stones, and a box of arrowheads labeled “Essex County” (M. Gibson, personal communication, 2008). In the bottom of the arrowhead box was a small note that read “Billingsly home.” The provenance of the trilobite fossil was not recorded, but available information on the rest of the estate suggests that the specimens were obtained from a not‐too‐distant source. This giant olenimorph trilobite, from a float (loose) specimen but evidently from the Middle Ordovician Effna Formation of Virginia, occurs in a matrix of limestone known in as a foraminiferal‐spiculitic wackestone. Although this represents a float specimen lacking record of its original discovery site, it can (very fortunately for the scientific purposes of this book) be placed in its exact formation because of the presence of distinctive “fine sinuous spar‐filled tubules” as described by Read (1978). It took quite a bit of geological detective work to arrive at this conclusion. A search should be undertaken immediately to locate the bedrock source of the giant trilobite, assuming of course that the rocks of interest are indeed exposed at the Earth’s surface and can be found. Sometimes float samples are the only evidence we have for rock formations whose bedrock remains completely buried underground or, worse, completely destroyed by erosion. 30 The unusual spar (calcite) filled tubules are shown as follows in Figure 4.2. The origin of these tubules is currently mysterious, and whether they represent some kind of fossil is unknown. They could conceivably represent partially fused sponge spicules (McMenamin 2008), but this is not certain. Figure 4.2. Fine sinuous spar‐filled tubules distinctive for the Ordovician Effna Formation as seen in a petrographic thin section. Note “+” shaped sponge spicule to the lower right. This thin section and all other sections mentioned in this book are cut from the same piece of rock that produced the giant trilobite. Sample 1 of 4/11/08. Greatest dimension of tubules 0.5 millimeters. Foraminifera are tiny marine microbes with calcareous skeletons, whereas the spicules are fossils from disarticulated marine sponges. The foraminifera represent undescribed types that are evolutionarily convergent on later forams in an evolutionarily iterative process not dissimilar to that hypothesized for diatoms by Pivar (2009). With an estimated total body length of up to a half‐meter, this is the largest olenimorph trilobite known. The occurrence of other olenimorph trilobites has been associated with dysaerobic facies and sulfide‐rich environments, leading Fortey (2000) to suggest that the greatly elongated thoraxes of these trilobites were indicative of a chemosymbiotic lifestyle. As the new trilobite, Torolenimorpha longa n. g. n. sp. occurs in an oxygen rich and presumably photic zone depositional environment, and has a very thin cuticle; it seems reasonable to consider the possibility that this represents a photosymbiotic trilobite. If so, Torolenimorpha longa n. g. n. sp. is evolutionarily atavistic with regard to presumably photosymbiotic animal members of the Ediacaran biota, such as, naturally, Vendoglossa tuberculata. The cuticular surface of Torolenimorpha longa n. g. n. sp. is unusual for a trilobite and especially for a large, Ordovician trilobite. The cuticle appears soft, easily wrinkled and not particularly well mineralized as seen in Figure 4.3. In arthropods, the cuticle will often crinkle up right before the animal molts its hard outer carapace. The impression given by Torolenimorpha longa n. g. n. sp. is that of a permanently soft‐shelled trilobite. 31 Figure 4.3. Wrinkly and weakly mineralized cuticle of the giant trilobite Torolenimorpha longa n. g. n. sp. Although clearly part of a trilobite pleural (thoracic) region, the segmentation strongly resembles the transverse banding of Vendoglossa tuberculata as seen in Figure 2.1. Should this banding be best interpreted as metameric arthropod segmentation, or as morphogenetic banding on the surface of the trilobitoid torus? Note the red crayon flecks on the surface of the specimen! Sample 1 of 4/11/08. Scale bar in centimeters. I interpret the soft‐shell nature of this trilobite as evidence that its cuticle was adapted either to transmit light, for photosymbionts below the cuticle, or perhaps for ease of absorbing hydrogen sulfide or other compounds essential for chemosymbiosis as has been suggested for other olenimorph trilobites by Richard Fortey (2000). Fortey’s chemosymbiotic olenimorphs have normal, mineralized cuticle, so perhaps the former possibility is most likely in the case of Torolenimorpha longa n. g. n. sp. Torolenimorpha longa n. g. n. sp. and other olenimorph trilobites achieved their unusual shape and size, from the perspective of torus theory, by a posterior elongation of the toroidal membrane to allow the surface area required for an unusual feeding strategy. As such, Torolenimorpha longa n. g. n. sp. represents an opposite case in comparison to the contraction of the elongate torus in the isotelid trilobites, where much of the body had to nest beneath a cephalic and pygidial shield, and the two shields had to match exactly, a 32 requirement that would be facilitated by a shorter, fatter toroid. Thus, the two largest known trilobites (both types are Ordovician in age), an Isotelus and Torolenimorpha longa, gain their size by manipulation of the toroidal morphogenetic field. Certainly there would be a genetic component to this field manipulation, but as is the case with heterochrony (Gould 1977), presumably rather small genetic changes can lead to major morphologic change. Although the section of the fossil shown in Figure 4.3 is clearly part of a trilobite pleural (thoracic) region, the segmentation rather resembles the transverse banding of Vendoglossa tuberculata as seen in Figure 2.1. Both cases give the impression of having formed in situ rather than having been added by successive addition of metameric segments. Metameric segmentation is the segmentation type considered to be standard in arthropods and annelid worms, but we should carefully consider Jenkinson’s (1909, p. 158) famous comments about system‐wide differentiation: The factors which the differentiation of the whole and of each part depend are essentially internal, and all that happens is that by a continued process of cell division the parts are separated from one another and the structure thus made palpable and manifest. Both Urtorus and Torolenimorpha provide evidence for the accuracy of Jenkinson’s (1909) insight. The transverse banding in each may be likened to the alternating dark blue and light blue bands of the Torus Cap as seen in Figure 1.1. Indeed, the cuticle of Torolenimorpha resembles nothing so much as a piece of somewhat rumply, coarsely textured corduroy fabric. 33 Chapter 5: Scleritome Morphogenesis IN HIS CRITIQUE of biological structuralism, Bob Hazen (Mazur 2008) asked how changing length‐to‐width ratios influences segmentation. Hazen criticized the model by noting that “self‐organizing patterning” develops “simply through local chemical signaling or diffusion‐controlled reaction process.” His implication was that this rendered unnecessary any attempt to “to bring toroids into such surface patterning.” This view has widespread support, for example the LALI‐type reactor diffusion systems (TUR dynamical patterning module) that can “generate regularly spaced spots or stripes of morphogen concentration” which can, in turn, “induce primordia of skeletal elements” (Newman and Bhat 2008). This is an important criticism that I can now directly address with evidence from the fossil record. I hope to demonstrate here that diffusion processes alone, important as they may be for the generation of divaricate shell patterns and the like (Seilacher 1972), are insufficient to account for the nature of the metazoan scleritome. This can only be explained by reference to a morphogenetic field as expressed by an elongate or elliptical toroid metazoan body plan, essentially the same body plan as represented by Vendoglossa tuberculata The fossil record provides some rather convincing evidence for the critical importance of this toroidal field, and quantification of the results are quite possible in this case. Consider the toroidal membrane shown in Figure 2.2, and note both latitudinal and longitudinal lines on both the inner and outer surfaces of the toroidal membrane. Let’s refer to the openings at either end of the toroid as the poles. As on a conventional globe of the earth, the lines of longitude converge at the poles. In other words, the spacing between the lines of longitude gets smaller and smaller as you go north or south, and vanishes to nothing at the poles. This geometrical observation is critical for understanding scleritome theory from the perspective of morphogenetic torus theory. Scleritome theory was developed by Stephan Bengtson, Ed Landing, Simon Conway Morris, and others in the 1980s as a way to explain small shelly fossils that were turning up in impressive numbers in the Lower Cambrian limestones that paleontologists were searching for clues to the origin of animal phyla (Valentine 2006; Landing 1984). Interest in this area was so high at the time that I was able to make some modest contributions to the field and Chinese and other international paleontologists became extremely interested. This was very exciting for me as a young scientist (McMenamin 2008). In May 1986 I attended a geological workshop in Uppsala, Sweden, entitled “Taxonomy and Biostratigraphy of the Earliest Skeletal Fossils.” The purpose of the workshop was to help paleontologists answer questions about the tiny fossils from the 34 Cambrian Period that were attracting a lot of geological attention. Most of these fossils are shells or shell fragments about a millimeter or less in length, causing geologists to nickname them “small shelly fossils.” I had with me at the time a trove of new specimens from my field research in Mexico. These specimens proved to be of use at the meeting. Several senior paleontologists had brought fossils that they claimed represented ancient jellyfish relatives. Using the Mexican material, I was able to show that their specimens were in fact a type of shellfish known as a mickwitziid brachiopod (McMenamin 1992). They later thanked me for saving them from publishing an erroneous account of the fossils. Geologists at the meeting were keenly interested in the Mexican specimens of what eventually proved to be the earliest type of shelly animals. They belong to a group known as the cloudinids. Cloudinids grew shells shaped like tiny, nested cones or conical tubes. They occur as fossils in Namibia, Mexico, Brazil, China and elsewhere. I classified the Mexican species into the genus Sinotubulites, a genus first described from China. A debate over whether the fossils ought to be called Sinotubulites or instead, Cloudina, simmered for twenty years, with some paleontologists opting to use both names to describe different types of cloudinids, and others placing all the cloudinids within the single genus Cloudina. The controversy was recently resolved in favor of the two name convention, preserving a distinction that has proved important for the paleontology of early animals (McMenamin 1998; Chen et al. 2007). One of the fossils I had brought to the meeting that generated considerable interest was a specimen of the small shelly fossil Microdictyon. The fossil, only a millimeter or so across, looked under magnification (Figure 5.1) like a porous bit of fine lacework, with a round outline and with a geometrical pattern to the pores. 35 Figure 5.1. Microdictyon multicavus McMenamin 2001. From acid maceration residue of Unit 3 of the Puerto Blanco Formation, northwestern Sonora, México, MM‐82‐49. Maximum height of specimen 0.7 mm. Note the resemblance of the geometric pattern seen here to the pattern of Torus Cap lumps as seen in Figure 1.1. Most small shelly fossils are recovered from rock by being dissolved out of limestone with acid in a process known as acid maceration. This specimen, however, had the unusual distinction of showing the tiny fossil right on the natural weathered limestone surface. This was the first Mexican Microdictyon known to science and thus useful for the science of paleobiogeography. But it did not help us understand much about the biology of Microdictyon. This problem was solved a few years later by Chinese paleontologists, who discovered complete specimens of the Microdictyon animal. Evidently many of the small shelly fossils were tiny bits of mail‐like skeletons, formed of tiny skeletal bits called sclerites. The unified whole of sclerites on the surface of a single animal is known as a scleritome. Intact scleritomes are only rarely encountered as fossils, but when found, they prove to be extremely important for helping to determine the biological affinities of the scleritome bearer. Perhaps the best example of an intact scleritome comes from Lower Cambrian rocks of the Sirius Passet region of Greenland. This fossil is called Halkieria evangelista, and gives us otherwise lost information about the morphology of these spiny animals. Halkieria evangelista is a worm or slug like creature a few centimeters in length. If it were naked it would probably resemble something like a somewhat elongate version of Urtorus. The upper surface of Halkieria evangelista, however, is covered in several types of pointed sclerites from snout to tail. These fossils had been studied before the Greenland discovery as disarticulated pieces, and nobody could really make heads or tails of them so 36 to speak. But with the fossilized scleritome in hand, it was possible to put all the pieces of humpty dumpty Halkieria back together again. The complete specimen offered some big surprises (Conway Morris 1998). At both the head and tail end of the animal were very large sclerites that looked for anything like the half shell of a brachiopod. A brachiopod is a bivalve, clam‐like marine shellfish that in fact is unrelated to clams. If the two large sclerites of Halkieria had been seen in isolation, and this has probably happened multiple times as paleontologists picked through their acid maceration residues, they would have been mistaken for isolated brachiopod shells. Halkieria experts have even argued, with good reason, that brachiopods are descended from halkieriids, and that the brachiopod body form is in fact a foreshortened halkieriid (Conway Morris 1998) that has lost its small midriff sclerites and is down to only two, the dorsal valve and the ventral valve. This of course requires a bend in the body torus that is more or less evolutionarily convergent on the isotelid trilobite case as described above. We must now ask: Why did halkieriids grow intact valves on either end of their scleritome? Pan‐selectionists are thrown for a loss here. Surely the halkieriids were not consciously anticipating some future bivalve form, and were growing the shells in advance just to be ready! It was once seriously argued that the anterior and posterior protovalves were used to block off the front and back ends of a U‐shaped burrow. I think this is pretty unlikely, because the burrow would have to be actively maintained to be exactly the right length otherwise the protovalves would not be much use at all. Natural selectionistic thinking has been here taken too far once again. The answer must involve the morphogenetic field of the torus. Recall that the lines of longitude converge as you approach the poles. There may be some critical density of field lines that triggers a transition from individual large sclerite (in its own, roughly square box of longitude and latitude) to tiny and perhaps fused sclerites (where the boxes pass some threshold of rectangular elongation). The animal is somehow induced to form sclerites only on its upper surface. If this were not the case, we might expect four protovalves to form, one above and one below. As you can see, it is the toroidal field that is controlling skeletal morphology. Natural selection had less to do with protovalve genesis than it might first appear to an evolutionist. This has far‐reaching implications that we will explore further. A Siberian small shelly fossil known as Maikhanella nicely demonstrates the field genesis of protovalves. Maikhanella is a protovalve from a halkieriid‐like Cambrian creature whose articulated scleritome remains unknown (Bengtson 1992). Isolated sclerites of Maikhanella continue to turn up in places like Sichuan, China (Steiner et al. 2004). However, the protovalve of this animal is important, because it can be seen to be composed of tiny, partially fused sclerites. Ed Landing was among the first to discover fused sclerites among small shelly fossils (Landing 1984). I was recently able to show that sponge spicules form by fusion of smaller, simpler sponge spicules (McMenamin 2008). But with Maikhanella, we see sclerite fusion under local control of a morphogenetic field. Homeotic gene control might be involved here as well, and this is plausible as homeotic genes are involved in many developmental processes. But there is no blueprint per se for a protovalve in the genome. 37 If we get closer to the toroidal pole, we see the lines of converging longitude getting closer and closer. We would thus expect the sclerites to get smaller and smaller, almost to the vanishing point, and this is indeed what we see. Mollusks such as snails feed by means of the molluscan radula. Radulas date back to the Cambrian (Butterfield 2008). The radula is shaped like a sanding belt and has a motion like that of an escalator. The radula is covered with tiny teeth, composed of the tough iron mineral magnetite, and is used by the animal to grind away at its food sources. Snails, limpets (a kind of snail) and chitons use their radulas to grind away at rock and eat the algae and bacteria that live in the interstices of the rock near its surface. Mushroom‐shaped islands have been formed in shoreline limestone cliffscapes by this grinding action. These islands eventually topple over when the snails finish chewing through the rocky stalk. Cephalopods (squid, octopus, nautiloids, ammonites) have radulas as well, and these are usually combined with a biting parrot‐like beak. Squids and ammonoids have seven radular teeth in each transverse row of radular sclerites, whereas in Nautilus there are nine teeth in each transverse row (Nixon 1996). The cephalopod family Bolitaenidae has radular teeth that look very much like the teeth or elements of conodonts, an extinct family of marine early chordates that actually made dentine like we do. The radula is a miniature scleritome, formed by the tight convergence of latitude lines near the anterior pole. The sclerites do not fuse in this case, but rather retain their separate identity in order to function as the business side of the grinding radula. Interestingly, disarticulated radular teeth are so common that they are thought to impart a magnetic signature to sedimentary rocks, quite useful for paleomagnetic studies. After the snail dies and the radula soft tissue decays, the tiny disarticulated magnetite teeth orient themselves as tiny magnets in the silt. The Cambrian to Ordovician chiton Matthevia is a nice paleontological demonstration of the toroidal scleritome. Most reconstructions of Matthevia show the spiny sclerites along its back as largest at the dorsal center of the animal, and the sclerites decreasing in size in both the anterior and posterior directions as the field lines converge. This is very much in accord with the fact that the morphogenetic torus field boxes are largest right along the equator of the torus. Interestingly, the Stinchcomb and Darrough (1995) reconstruction of Matthevia shows the sclerites becoming relatively narrower, in accordance with the rectangularization of the field boxes (delineated by roughly orthogonal field lines) as one approaches either pole, respectively. Of course, there is much room here for genetic manipulation of sclerite shape and arrangement in any particular organism. Sclerites in many types of chitons, for example, also decrease in size as you approach the side of the animal. It seems clear, however, that the torus morphogenetic field primarily controls sclerite placement and size. The mickwitziid brachiopods mentioned earlier (McMenamin 1992) are an Early Cambrian group that does indeed seem to be descended from halkieriid‐like metazoans that had many sclerites. The original scleritome was geometrically arranged over the body of the animal, something like what we see today in spiny aplacophoran mollusks and there is even a hint of it in the problematic gastrotrich metazoans. Some early brachiopods, and I 38 would include at least some of the mickwitziids in this list, were probably unable to completely close their shells because they had not yet used the toroidal field to match their anterior and posterior valves. My student Tracy Ryan (Ryan 2003) discovered that the Ordovician brachiopod Apheorthis lineocosta was probably unable to close its shells because of a serious valve mismatch. Thus it represented an evolutionary holdover from the Cambrian, a stem‐group brachiopod that never got around to actually closing up its shell. We can mathematically model the scleritome field by plotting the following formula using Jiho Kim’s online GCalc 3.0 graphing program: f(x)=sqrt(5‐(abs(x)^1.05)) Equation 1 In other words, the function f(x) is equal to the square root of five minus the absolute value of x raised to the 1.05 power. This will produce a curve that simulates the dorsal profile of a slug‐shaped scleritome‐bearing Cambrian animal. Figure 5.2. Graph of the scleritome function f(x)= sqrt(5‐(abs(x)^1.05)). This curve models the dorsal profile of a scleritome‐bearing animal. The sclerites would ornament the top surface of the curve. 39 We can use this plot to identify regions of the field where sclerite fusion or miniaturization are most likely. Individual sclerite width will be at a maximum when the derivative of the function F(x) is set to zero, in other words, right at the center of the plot in Figure 5.2. For the purposes of calculation we will introduce two parameters, a and b. Let’s set a to have a value of 3, and b to have a value of 4. The f(x) curve intersects the x axis at c and –c. Values of the function from 0<|x|<a will show large individual sclerites, with sclerite maximum size decreasing as per the graph shown in Figure 5.2. Values from a<|x|<b constitute the protovalve zone, where clusters of small (but not too small) sclerites are likely to fuse at nodes that resemble the holes in the image in Plate 10, top image of Pivar (2004, p. 31). Values from b<|x|<c (with F(|c|)=0) will tend towards either sclerite loss or sclerite miniaturization; this could be called the radula zone. In certain situations the polarity of the greater‐than signs can be reversed, as in 0<x<a, a<x<b, b<x<c, the case for sharks and other elasmobranchs who have the tiny sclerites at the torus equator (sharkskin) and the larger ones at the anterior pole (rows of shark teeth). Note that teeth can also evolve (or re‐evolve) independently, as for instance in the extinct placoderm fish, in another astonishing case of convergent evolution (Smith and Johanson 2003; Stokstad 2003). These neo‐teeth nevertheless remain under the influence of toroidal morphogenesis, as multiple or set‐back rows or arrays of neo‐teeth are also known to appear in these fish. These examples constitute the fragment of truth in Erasmus Darwin’s motto e conchis omnia (“from shells come all things”), which we might modify to e conchis minutis omnia. From little shells all things. Some extinct sharks such as Stethacanthus from the Late Devonian (Maisey 1996) have medium grade sclerites in bizarre head projections in the a<x<b zone. The same is seen in the stethacanthid shark Damocles serratus, named for the sword that hung over the head of Damocles in ancient Greek legend (Ellis 2001). The Late Jurassic rabbitfish (chimaeroid) Ischyodus shows similar development in its curious “head clasper”, a cartilaginous projection capped by sharp sclerites (Maisey 1996). Sharks form interesting tori; the intestine of a dogfish for example is spiraled to form a hindgut with sufficient surface area for digestion. Could the bizarre spiral coils of large sclerites/teeth in certain extinct sharks (genus Helicoprion) merely represent a sympathetic response in the anterior torus to digestive spiraling in the posterior torus? In any case, the bizarre spiral tooth set of Helicoprion may have been deployed in a way similar to the molluscan radula on a currently unknown food source, only this time with an odd rotary motion to form a living rotary slicer coil. This seems more reasonable than the circular saw model preferred by many authors for helicoprionids. If I am correct about this, the idea solves the long‐standing paleontological mystery concerning the function of Helicoprion tooth arrays. This all predicts that there should be a ring of sclertized tissue in the a<|x|<b or a>|x|>b protovalve zones. This has already been illustrated by Pivar (2004, plate 38, p. 93) for the armadillo, where the toroidal articulated sphere is armored by fused intermediate sclerites to form the shoulder and tail scute shields. The armadillo appears to be evolving 40 into a land bivalve, and seems to have arrived at a degree of “bivalvedness” somewhat comparable to that of the stem group mickwitziid brachiopods. Let’s return for a moment to the Microdictyon sclerite seen in Figure 5.1. These sclerites are now known to occur in two rows along the flanks of the lobopod (catepillar‐like) marine animal. We can think of these as, say, a latitudinal row of dark blue lumps on the Torus Cap as seen in Figure 1.1, where the dark blue top of the cap may be thought of as the protovalve zone. This is clearly a genetically‐controlled departure from the a<|x|<b or a>|x|>b protovalve zone general rule. But it nevertheless seems reasonable to infer that the valve‐like sclerites of Microdictyon are built up of fused sclerites, as was the case for Maikhanella. Note the seemingly geometric arrangement of the presumed fused sclerites in Figure 5.1. It seems as if the sclerite itself has preserved the orthogonal array of morphogenetic field lines that characterize the animalian, toroidal dorsal exosphere. In other words, the Microdictyon sclerite is a fossilized patch of morphogenetic field! As expected, anterior and posterior porous sclerites in this animal are smaller than sclerites near its dorsal center. The field shows some structure in the immediate vicinity of each porous sclerite, for in a typical Microdictyon sclerite the constituent fused sclerite elements are small near the margin of sclerite and larger in its center. In any case, the toroidal topology seems to be the bedrock of the morphogenetic system, and this topology becomes clearly visible in certain particularly well‐disposed scleritomes. Let’s now return briefly to Ediacaran considerations. If we invert the image seen in Plate 10, top image of Pivar (2004, p. 31), we create the enigmatic (McMenamin 1998) Ediacaran organism Ausia. Like Urtorus, Ausia seems to be an expression of what might be considered a more or less pure toroidal membrane. I am referring here of course to the animalian members of the Ediacaran biota, rather than the bizarre vendobiont/rangeomorph Ediacarans that grow by unique, metacellular morphological rules of their own (McMenamin 1998). Many of the true animals in the Ediacaran biota seem to be experimenting with the morphogenetic torus, just as their weird vendobiont neighbors explored metacellular iteration space. As a final consideration, there is evidence that the sclerite morphogenetic field can reemerge at unexpected times. Cretaceous titanosaurid sauropod dinosaurs apparently reactivated a dermal scleritome of plates and scutes, after a long Jurassic history of sauropods where such sclerite ornamentation was rare. But the most bizarre case of an apparently reactivated scleritome morphogenetic field is in a recently discovered deep sea vent species of gastropod. Crysomallon squamiferum, the scaly‐foot gastropod, was discovered in 2001 living on the central Indian mid‐oceanic ridge, associated with black smokers at the Kairei deep sea vent field (Warén et al. 2003). The snail has a fairly ordinary looking snail shell, but the foot of the snail is anything but ordinary, as it is covered with a scleritome of sclerites composed of the iron sulfide minerals pyrite and greigite. This strange scleritome might seem to be unique, but it is important to recall that the radula (as seen in snails and chitons), itself a miniature scleritome, is also composed of iron minerals. Thus, certain mollusks are able to construct an iron scleritome alongside a calcareous scleritome. This demonstrates the flexibility of morphogenetic fields with regard to biomineralization, and 41 their utility in facilitating various types and compositions of scleritomes, sometimes within the same animal. I predict here the discovery of a stem group fossil mollusk that has an external skeleton consisting of both iron and calcareous sclerites of comparable size, perhaps occurring in a geometrical array, as part of the same scleritome. 42 Chapter 6: Vertebrate Teeth and Zahnreihen Mark A. S. McMenamin and Amanda Lepelstat THE ZAHNREIHE CONCEPT was applied by Bolt and DeMar (1975) to understand what appeared to be tooth migration in lizard‐like Permian captorhinomorph reptiles. Zahnreihen analysis was developed to cope with a difficult problem that researchers had encountered, namely, how in tetrapods with many rows of teeth (such as captorhinomorph reptiles), the teeth appeared to move from the lingual (tongue) to the labial (lips) side of the jaw. These teeth had already been firmly set in the jaw, that is, been connected to the jaw by attachment bone, and there was no evidence of teeth moving through the ossified jaw. The pattern of tooth motion was accompanied by rotations of the upper and lower jaws (Ricqlès and Bolt 1983), to form an odd and unexplained pattern. Under Zahnreihe analysis, teeth are organized into linear rows called zahnreihe (plural: zahnreihen). The oldest tooth in each row is the tooth that is most anterior, and teeth are added to the posterior end of each row. These rows do not necessarily parallel the edges of the jaw; in fact, they can run at an acute angle to the outline edges of the jaw (Figure 6.1). 43 Figure 6.1. Dorsal view of right jawbone of Captorhinus aguti. Redrawn from de Ricqlès and Bolt (1983, their Figure 4C). Solid lines connect the zahnreihen, and are interpreted here as morphogenetic field lines. Scale bar = 1 cm. In addition to captorhinomorph reptiles, the Zahnreihen Concept has also been applied to Triassic marine reptiles (Sander and Faber 2005). These Permian and Triassic reptiles are quite in accord with the second law of morphogenetic evolution as stated earlier, namely, that evidence for developmental control by morphogenetic fields is most apparent in the earliest representatives of any particular lineage. Ricqlès and Bolt (1983) were primarily interested in Zahnreihen as a way of understanding the taxonomic differences between different types of Permian reptiles. Ricqlès and Bolt (1983, p. 22) were quite honest, however, about the puzzling nature of Zahnreihen as it applied to jaw morphology: We would emphasize, however, that this descriptive usefulness of Zahnreihen does not imply a particular ontogenetic and/or functional mechanism. Elucidation of such mechanisms is a separate problem. [emphasis added] We are now in a position to elucidate the puzzling zahnreihen pattern. The tooth rows represent morphogenetic field lines that converge as the lines reach the mouth cavity, exactly as required by the ur‐torus model. Without fully realizing what they were doing, Ricqlès and Bolt (1983, their Figure 4C) sketched in these field lines in their line drawing of 44 dorsal occlusal view of a right dentary (jawbone) of Captorhinus aguti. The teeth are following the ancient Cambrian pattern of mineralization at intersections of a roughly orthogonal morphogenetic field grid, thus re‐establishing in the oral region of the reptile a scleritome composed of individual sclerites, in this case the reptilian teeth. A complete scleritome, as seen in Halkieria, thus represents a well developed series of Zahnreihen. The halkieriid scleritome becomes miniaturized, in a convergent fashion, in the tiny tooth‐covered radula of modern mollusks. Zahnreihen analysis might be fruitfully applied to the radula as well. This comparison indicates that we are getting close to the fundamental explanation of morphogenetic patterning in complex life forms (Thompson 1971; Pivar 2009). We are seeing the collapse of Modern Synthesis biology, which depended so heavily on natural selection as the driver of morphological innovation, as predicted by McMenamin (1998; 2009) and so skillfully reported by Mazur (2009). The following example will suffice to demonstrate the validity of the morphogenetic field scleritome model for vertebrate fossils. Pycnodont fish (the name means “dense teeth”) are an unusual group of bony fish that range in age from the Triassic to the Eocene. They are known from Mesozoic and Paleogene deposits in North America (Kriwet, 2008), Brazil (Maisey 1991), Germany (Desalte and Kriwet 2005; Kriwet 2008) and north Africa (Longbottom 1984). This remarkable yet still relatively poorly known fish group is characterized by a deep body that somewhat resembles that of an ocean sunfish. Pycnodont fish reached a meter or more in length. 45 Figure 6.2. Articulated pycnodont zahnreihen recovered from the Khouribga phosphate mine, Morocco. Specimen prepared from matrix by Amanda Lepelstadt. Scale bar in centimeters. 46 Figure 6.3. Articulated pycnodont zahnreihen, sketch of specimen shown in previous figure. Scale bar = 1 cm. The most striking characteristic of pycnodont fish, however, is their unusual dentition (Figures 6.2‐•6.3). The individual teeth, resembling fat corn kernels or tiny stromatolites, are typically arranged in rows. The mouth may have upper and lower arrays of teeth, or, more typically, form what appears to be a cylindrical space like a corn cob with the kernels inverted and turned inward (Figure 6.4). 47 Figure 6.4. Articulated pycnodont zahnreihen dentition, preserved in the fossilized mouth of Neoproscinetes from the Santana Formation, Brazil (110 million years old). Mouth opens to the right. Width of view approximately 8 centimeters. Kriwet (2008) has described a Late Jurassic pycnodontiform fish Athrodon wittei that is remarkable for its distinct tooth morphology and large number of lateral tooth rows. Kriwet (2008) notes that the “dentition of Athrodon differs from most other pycnodont dentitions in the peculiar arrangement of the teeth into irregular rows and [no] well‐differentiated principal row.” Kriwet (2008) considers this trait unique to Athrodon, but nevertheless compares it to the Texas pycnodont Nonaphalagodus. Nonaphalagodus also has a large number of upper jaw tooth rows, but these rows are arranged more regularly and in more distinct rows (Kriwet 2008). Clearly, the tooth rows in pycnodontiform fish represent zahnreihen, and genus level taxonomic distinctions may be resolved to differences in the deployment of the morphogenetic field lines that control the 48 arrangement of individual teeth in the pycnodont zahnreihen. The morphogenetic field control of the pycnodont dentition gives a huge boost to concepts of biological structuralism (Pivar 2009), the resurging concept that changes in morphogenetic fields, rather than gradual evolutionary change involving point mutations, can be held responsible for rapid evolutionary change at taxonomic levels ranging from genus level (pycnodont fish) to phylum level (Cambrian Explosion; Newman and Bhat 2008). This dawning realization completely alters our concept of evolutionary change, and requires us to test the fossil record for further examples of evolutionary change via field morphogenesis at both the microevolutionary and macroevolutionary levels. The analysis can be taken a step further. A giant semionotid fish species named Lepidotes maximus from the Lower Jurassic is on display at the American Museum of Natural History (Figure 6.5). Figure 6.5. Lepidotes maximus, Lower Jurassic giant semionotid fish, American Museum of Natural History. Amanda Lepelstadt for scale; note heterocercal tail to left of Amanda’s head. Photograph by Meredith Peters. 49 Figure 6.6. Lepidotes maximus, teeth in lower jaw of specimen seen in previous figure. Photograph by Meredith Peters. This fish has teeth that are strikingly similar to pycnodontid teeth (Figure 6.6). Semionotids and pycnodontids are not closely related, however, and belong to unrelated groups of neopterygian fish—the Semionotiformes and the Pycnodontiformes. Their similar zahnreihen arrangement of peg‐like or stromatolite‐shaped teeth appears to be a clear case of convergent evolution. The key point here is that the two different fish body plans are responding in a nearly identical fashion to morphogenetic field control of dentition, with the tubular mouth lined by zahnreihen teeth forming as the morphogenetic field lines of the ur‐torus sweep into the mouth in converging lines. This serves as a demonstration of comparable morphogenetic field control in both types of fishes. The first and second laws of morphogenetic evolution elucidated in this book are thus on full display in this semionotid‐pycnodontid example. Again: THE SAME FORCES THAT CONTROL MACROEVOLUTION CONTROL THE OBSERVED HIGH PRECISION OF CONVERGENT EVOLUTION. BOTH PROCESSES ARE ASSOCIATED WITH TRANSFORMATIONS OF MORPHOGENETIC FIELDS. 50 Clearly both the semionotid fish and the pycnodontid fish are responding in a nearly identical fashion to similar poles of their morphogenetic fields. The high precision of the convergence is due to the similarities in the respective morphogenetic fields. Now consider again that: EVIDENCE FOR DEVELOPMENTAL CONTROL BY MORPHOGENETIC FIELDS IS MOST APPARENT IN THE EARLIEST REPRESENTATIVES OF ANY PARTICULAR LINEAGE OF COMPLEX LIFE. Figure 6.7. Semionotus fultus (Agassiz), Triassic (Newark Series), Boonton, New Jersey, Mount Holyoke College sample number 2268. Two individuals plus part of a third at upper left. Scale bar in centimeters. The morphogenetic fields of semionotid fish (Figure 6.7) and pycnodontid fish are not identical, however. Semionotids often develop a fairly primordial fish body plan, as indicated by the fleshy lobe in the upper part of the caudal or tail fin. This type of tail is 51 known as a heterocercal tail (Figure 6.8), and is seen in fish groups such as sturgeons and sharks that are considered to be less morphologically advanced (or less evolutionarily derived). Figure 6.8. Semionotus tenuiceps (Agassiz), Triassic (“Chicopee Shale”), Sunderland, Massachusetts, Mount Holyoke College sample number 2391. Note the elongation of the fleshy part of the tail in the upper caudal fin vicinity (heterocercal tail). Scale bar in centimeters. This may be evidence of a more primordial morphogenetic field in semionotids. Their field lines are therefore most sharply bent in the vicinity of the upper part of the caudal fin, as the lines of the ur‐torus sweep into the anal pore, dragging the top of the tail with them. The field line bending is thus responsible for the fleshy upper lobe of the heterocercal tail. It may be possible for the morphogenetic field lines to stretch at the anterior end of the fish, as for example in the curious snout of the Jurassic to Eocene aspidorhynchid fish Aspidorhynchus (Maisey 1996). The elongate geometrical scales on this fish seem to be emphasizing the transverse as opposed to the longitudinal field lines. 52 D’Arcy Wentworth Thompson (1971, figures 146‐155) used a memorable, rectangular grid pattern to show how deformations of a body plan gridwork could lead to changes in fish morphology. In a funhouse mirror set of illustrations, Thompson (1971) transformed Argyropelecus olfersi into Sternoptyx diaphana, Scarus sp. into Pomacanthus, Polyprion into Pseudopriacanthus altus, Scorpaena sp. into Antigonia capros, and Diodon (the porcupine fish) into Orthagoriscus mola (the ocean sunfish). Thompson’s (1971) concept of deformations on a rectilinear co‐ordinate system is both fascinating and valid, but can be improved and completed by using a toroidal coordinate gird. Recurving of the anterior field lines can help explain the zahnreihen morphology of semionotid fish, pycnodontid fish, and other vertebrates. Figure 6.9. Semionotus bergeri, Upper Triassic (Rhaetic beds), southern England, Mount Holyoke College sample number 4224. Scale bar in centimeters. The symmetrical, crescent‐shaped tail of pycnodontids (homocercal tail) is more typical for modern‐style (neopterygian) bony fishes. As you may be guessing by now, of 53 course, the homocercal tail has evolved repeatedly by convergent evolution. True to the second law of morphogenetic evolution, the more “primitive” semionotid fish have a scale pattern (Figure 6.9) that is a highly geometrical expression of the morphogenetic field, with rows of scales forming a scleritome or curved zahnreihen pattern, that almost seems to mirror the platelet placement in the Early Cambrian spindle‐shaped echinoderm Helicoplacus. Semionotids, helicoplacoids (Figure 1.3) and other extinct scleritome bearers such as the halkieriids carry in their external body form a fossil representation of extinct morphogenetic fields. These morphogenetic fields probably underwent more‐or‐less saltational transformation when the groups first appeared, in the cases considered here early in the evolutionary history of their respective groups. We might even say, particularly with the helicoplacoids (Figure 1.3), that the initial body form does not appear to be particularly adaptive, at least in terms of an obvious feeding strategy. How could natural selection evolve such a form by slow, incremental steps to an apparently maladaptive body form? The evolutionary change was more likely abrupt, and indeed the appearance of helicoplacoids is part and parcel of the Cambrian explosion (Wilbur 2006). There seems to be no provision for filter feeding in helicoplacoids, and even the exact position of the mouth has been a topic of controversy. The spindle‐shaped body makes little or no attempt to minimize its surface area‐to‐volume ratio in any discernable way, thus Helicoplacus cannot even be held up as a likely candidate for photosymbiosis or even chemosymbiosis. Osmotrophy may be a possible feeding strategy for helicoplacoids (McMenamin 1993), but it is fair to say that the body plan of helicoplacoids appears to owe a greater part of its form to a slightly twisted, spindle‐shaped morphogenetic field than to any type of sculpting by natural selection. Unlike the case with Urtorus (Figure 2.1), there are both sets of field lines visible on the fossil this time. And rather than being triumphs of adaptation, helicoplacoids seem downright maladaptive. This may partly explain why they evidently go extinct before the close of the Early Cambrian. Morphogenetic field analysis also gives us an explanation for the convergence in tooth form that is so commonly encountered in early mammals. The cutter and grinder halves of molars, convergently evolved in both true tribosphenic mammals (placentals, marsupials, and multituberculates) and pseudo‐tribosphenic mammals (Jurassic Pseudotribos, egg‐laying monotremes; Luo et al. 2007), indicate that morphogenetic field lines can pass through as well as between individual teeth. This and many other examples of molar convergences suggest that the formation of molars represents a fairly “easy” morphogenetic change—just fuse adjacent pairs of zahnreihen, or compress morphogenetic field lines, to form the cusps. This may be seen in mammals as different as the small Oligocene rodent Phiocricetomys minutus, where a pair of zahnreihen lines may pass right through the crown teeth (right M1‐3, Figure 16D of Simons and Wood, 1968), and the bizarre Oligocene aquatic desmostylan mammals, whose molars resembled clusters of pipes (stacked zahnreihen rows). Molar convergence is so strong between the molars of the bamboo‐munching, extinct Gigantopithecus (at 10 feet tall, the largest known primate) and Homo sapiens that the former was once thought to be ancestral to the latter (Ciochon 1988). The presence of bicuspid teeth in Permian reptiles shows that the potential for molarization was present early on in reptile evolution (Bolt 1980). Finally, returning to the fishes, we see the odd case of zahnreihen consisting of teeth with multiple cusps (nascent 54 molarization) in the omnivorous Tambaqui or Pacu (Colossoma macropomum) from the Amazon basin (Lundberg et al. 1986). In summary, a peek inside the mouth of the Frilled Shark (Chlamydoselachus anguineus) provides a stunning confirmation of the link between sclerite fusion and morphogenetic fields. The teeth of this deep water, living‐fossil shark show zahnreihen rows of trident‐shaped, three‐pronged teeth. The teeth of each clearly distinct zahnreihe seem geometrically ornate beyond what is required for the capture of swimming prey. A dying specimen caused a minor sensation on YouTube in 2007 when it was captured on video at the Awashima Marine Park in Numazu, Japan. In my opinion, the sea monster appeal of this video was dramatically enhanced by the fact that the fish swam with its mouth open, displaying its hundreds of trident teeth in more than twenty zahnreihen rows, resembling Poseidon’s army on the march. No chordate shows its anterior scleritome in a more strikingly geometric a fashion, however, than the rather sinister array of teeth in the mouth of a lamprey. The lamprey scleritome, once again, obeys the second law of morphogenetic evolution: EVIDENCE FOR DEVELOPMENTAL CONTROL BY MORPHOGENETIC FIELDS IS MOST APPARENT IN THE PRIMORDIAL REPRESENTATIVES OF ANY PARTICULAR LINEAGE OF COMPLEX LIFE. 55 Chapter 7: The Schadian Torus IN 1977 WOLFGANG SCHAD published a remarkable book entitled Man and Mammals: Towards a Biology of Form. In this book, Schad (1977) takes a close look at the polarity of familiar types of animals, and argues that the biotic investment of any particular animal can emphasize the anterior part of the animal, the posterior part, or any place in between along the axis of the animal’s body. The point of emphasis along the body axis (we would say here the long axis of the torus) comes with a cost, however, as investment in other parts of the body will be reduced accordingly. This is merely the same as saying that it is impossible to supersize all parts of one’s body at once. For example, if a dinosaur such as Brachiosaurus invests heavily (in a biotic sense) in massive forelimbs, then its tail and hind limbs will be comparatively shorter. Natural selection did not sculpt the hind limbs; they are merely a byproduct of anterior toroidal swelling. Brachiosaurus would thus contrast with a dinosaur such as Diplodocus, with its longer hind limbs and much longer tail. Triceratops has an anterior orientation with its massive body frill and horns (Lockley 1999). We see here an alternation between the anterior and posterior metabolic poles. Regardless of whether this ultimately involves homeotic or more purely morphogenetic factors or both (such as a genetic predisposition to contract or expand particular parts of the torus along its central axis), Schadian analysis explains much about animalian body form. Shadian analysis has been used in particular by Lockley (1999) to explain iterative evolution (in dinosaurs and mammals) of convergently evolved stance types among the tetrapod land vertebrates. Lockley (1999) sees a trifold development in two dinosaurian groups (Thyreophora and Cerapoda) and one mammalian group (Ungulata) of convergently evolved odd toed forms and then even toed forms with paired horns. Each of these three groups thus passes through an initial ancestral morphology, an odd toed stage (this would be the perissodactyls in mammals) and then an even toed stage (cloven‐hooved or artiodactyls in the mammals). This type of convergent evolution is called iterative evolution, and we will return to this concept later. Flightlessness in birds, for example, is often given a selectionistic interpretation, as in “use it or lose it.” Schadian morphogenetic analysis can also be applied here, as for instance in ostriches that make a very heavy investment in powerful hind limbs. This may have triggered wing reduction as a Schadian byproduct or ancillary consequence of hind limb investment. New Zealand’s flightless, extinct moas have even more massive hind limbs, and accordingly, completely lost their forelimbs. Moa wings are typically not seen even as vestigial remnants. Humans, by the way, have a distinctively balanced torus from a Schadian perspective: heavy investment in the anterior torus (large brain) and heavy investment in hind limbs for bipedal locomotion. Leonardo Da Vinci seemed to understand this through his artwork on human body form, as in his famous sketch Canon of Proportions, in the Academy of Fine Arts in Venice. This distributed, balanced investment 56 provides a potential explanation for why humans lost tails and body hair; these features went out of business, so to speak, because of our heavy investment of body resources elsewhere. 57 Chapter 8: Cephalopod Hypertorus THE COILED NAUTILUS shell might be called one of the seven wonders of creation. Favorite of artists, the shell when cut by a saw down the longitudinal midline to reveal its chambers is unquestionably a marvel of spiral form. Fossil ammonites (Figure 8.1), close relatives of the nautiloids, share this same form and were the first invertebrate fossils known to have been illustrated by human artists (McMenamin 2007). But where did this strange form come from? So different it seems from the modified sclerites we discussed earlier. Could it represent an individual sclerite (or a fusion of a large number of sclerites)? In other words, is the cephalopod spiral shell a scleritome that was morphed and expanded to fit over the toroidal morphogenetic field of the cephalopod mantle? Figure 8.1. A Mesozoic fossil ammonite cut to reveal the septal chambers. The open areas are chambers partially filled with calcite crystals. Width of specimen 17.2 cm. Mount Holyoke College specimen number 5217. It is easy for the trained eye to tell a typical brachiopod apart from a typical clam. Both the clam and the brachiopod have an exoskeleton consisting of two flattened valves; hence the term bivalve may be applied to both types of animals, whereas the technical term Bivalve is generally restricted for use only with clams. The brachiopod consists of two valves that are generally unequal in size even though they nest perfectly together. Each 58 valve has a line of symmetry passing through the flat part of the valve. Clams, by way of contrast, generally have a plane of symmetry that runs between the two valves. The valves are equal in size and represent mirror images of one another. The individual clam valves themselves are not symmetric but rather have a slight twist that displaces the beak of the shell to one side. These differences between clam and brachiopod are easily explained from the perspective of scleritome theory. The brachiopod valves, as you will recall, are evolutionarily derived from sclerites or sclerite clusters at the head and tail of the stem‐group brachiopod from which they are descended. This explains the plane of bilateral symmetry running through each valve. This is inherited from the original bilateral symmetry of the sclerite‐armored brachiopod ancestor. The clam skeleton, on the other hand, is derived from sclerites on either side of the scleritome‐bearing ancestor. This nicely explains why the plane of symmetry of clams, unless they have been modified by unusual body form as in oysters and rudists, runs right between the two valves. This plane was the plane of bilateral symmetry in the prickly scleritome ancestor. Snails and chitons such as Matthevia seem to have emphasized the sclerites right on the dorsal midline, as was the case with brachiopods, but rather than following the brachiopod case of selecting an anterior and posterior shell, the crawling mollusks seem to have selected a series of adjacent sclerites on the bilateral midline but close to the center of the animal, i.e., the equator of the torus. Thus the chiton has a series of plates along its back representing a semi‐great circle sclerite series, and in accordance with the laws quantified above, the largest sclerite occurs smack dab in the center of the series (at the toroidal equator). A splendid example of this relationship is seen in modern Chiton magnifica from the Chilean coast, whose largest of its eight main sclerites is right on the center dorsal midline. Gastropods or snails appear to have reduced the sclerite series of the chitons to just two, or in the case of the garden snail Helix, just one, or in the case of slugs, zero. A typical marine snail has a coiled main shell that holds its body, and an operculum to seal off the shell aperture in times of danger. In the earliest snails, the coil of the shell pointed in an anterior direction. In other words, early snails had a cornucopia‐like conical shell with the point of the curved shell oriented forward. This was (presumably) followed by a small patch of mineralization, a flat small sclerite that served as the operculum when the snail retracted into its shell. Interestingly, the opercula of modern snails are usually coiled, seemingly in sympathy with the coil of the primary shell. During snail evolution, as the shells got thicker, heavier, and more tightly coiled (in technical terms, lower whorl translation distance from the coiling axis), snails developed a problem. The heavy nut of the coiled shell began to press down heavily on the poor snail’s neck, and it required expenditure of a lot of energy to keep the darn thing elevated. One snail group put a twist in the entire body torus in order to flip the heavy part of the shell in 59 a posterior direction, so that it could rest on the snail’s tail rather than on the snail’s neck. This also made it easier to snap quickly into the shell in times of danger, as the shell opening does not need to be lifted up as far in this orientation. This process of torus twist, which may be observed directly in the ontogenetic development of a gastropod embryo, is called torsion. The earliest known cephalopods have shells. They first appear in the late Cambrian, and are evidently descended from a crawling mollusk that looked very much like (or so it is supposed) the untorted gastropod ancestor. As the story goes, the ur‐cephalopod developed septa (singular: septum) in the tip interior of its cornucopia shell. These septa filled with metabolic gas, being sealed off from the animal’s fleshy mantle by a thin sheet of shell that formed each septum. When enough of these septa were formed, the mollusk became increasing less dense because of its gas content, until one day in the Cambrian, pop! The startled creature lifted off from the seafloor and floated to the surface. Here we see another one of those problems that now beset selectionistic evolutionary biology. Popping to the surface, with no way of going back down, is a bad situation for you as a benthic marine organism. You are away from your preferred food sources, and are likely to be washed to shore where your gills are not going to function very well. You are going to dry out and die. Perhaps a few of these creatures survived to become the ancestors of land snails. But that is a far cry from a cephalopod like Nautilus or an ammonite. The standard adaptationistic story requires that some of these ur‐cephalopods floated just a little, and finding this handy for hopping from seaweed patch to boulder to seaweed patch, developed a way to regulate their buoyancy by developing a thin organ called the siphuncle through the septa in order to regulate the gas density in the chambers and hence the overall density of the animal’s body. Actually, the siphuncular openings probably have to develop as each septum forms because it would be very implausible (although stranger things have happened) for a mollusk to resorb preexisting shell and then thread a long fleshy organ through the bored holes. Any kind of optimization scenario involving natural selection seems less plausible in the face of these kinds of constraints. It is time to turn, once again, to the torus for a better explanation. I became aware of this fundamental problem for cephalopod origins by discovering a new type of Ordovician nautiloid in the vicinity of El Paso, Texas (see Nautiloid species A in Appendices). An interesting thing about the early (Ellesmeroceratid) nautiloids is that the siphuncle is not a tiny tube. It is huge, filling up nearly half of the shell interior. As such the nautiloid shell itself takes on the approximate shape of the torus, with the outer shell representing the torus exterior and the siphuncle representing the torus interior. This “skele‐multitorus” envelops the entire creature, as shown in Pivar’s (2004) diagrams, his p. 63 plate 27. It mimics the shape of a fleshy torus. Indeed, Ordovician ascoceratid nautiloids, possibly belonging to Billingsites multicameratus (Kesling 1961, p. 88), bear a strong resemblance to a toroid with a constricted aperture and transverse segmentoids as in Urtorus. There is a more than passing resemblance, in fact, to the chrysalis stage of butterfly morphogenesis as seen in 60 Pivar (2009). This resemblance is more than merely coincidental, and represents in the cephalopod a toroidal skeletal sheath expanded over a portion of the mantle toroid. The siphuncle is thus an inherent part of the system as it must obey the laws of the morphogenetic torus. Kesling’s (1961) figure 1 shows three variants on the toroidal conch of ascoceratid cephalopods, with the globular toroid being best developed after the early, narrow (cyrtoconic) part of the shell has broken off in a process known as truncation. The cephalopod shell can thus be considered as a hypertorus, a series of nested and fused imbricated dorsal toroidal caps (Figure A.3). The cephalopod shell, as for instance in a nautiloid, represents a bulbous cap cover over the toroidal body of the animal that has been bent in half. Nautiloid septa bow in the direction of the innermost spiral. In ammonites, on the other hand, the septa can bow toward the shell aperture. This is due to gas backpressure against the mantle torus before the onset of septum skeletonization. Complexity of the outer edges of each septum in ammonites is distinctive for each ammonite species. The reason for this complexity, and for the complex suture line that is formed where each septum meets the inner surface of the outer shell wall, is a long‐standing paleontological conundrum. I do not have the answer to this mystery but I am willing to wager that the solution has something to do with a flexible proto‐septum membrane that separates the gas of a newly‐forming septal chamber from the mantle toroid. Cephalopod shells have been modified in a variety of really innovative and unusual ways. Sepia, the cuttlefish, turns the shell into an internal stiffening blade, and the extinct, squidlike belemnites turn the shell into a massive cigar‐shaped internal skeleton, presumably required to counterbalance their high buoyancy tissue fat content. The shell in cephalopods may even be lost altogether as in the case of the octopus, which nevertheless retain their radula and thus are not entirely soft‐bodied. 61 Chapter 9: Convergent Forams and Iterative Evolution FORAMINIFERA or forams are typically tiny marine microbes with shells or tests composed of calcium carbonate, small rock fragments glued together, or other substances. They have a long geological history, going back to Cambrian or even Proterozoic times. The oldest forams tend to be very simple in terms of their morphology, and this makes them hard to classify and even hard to distinguish from other types of small organisms such as algae and small animals that might also have had a simple tubular or spherical test. For example, Thuramminoides specimens from Middle Cambrian shales of the Czech Republic look like tiny, flattened squash balls (Bubík 2001). Test‐forming foraminifera are presumed to be descended from Precambrian amoeboid foraminifera that lacked any kind of a durable skeleton. Most forams are about a half‐millimeter in greatest dimension, although certain types in the Late Paleozoic and the Cenozoic reach giant size. Giant late Paleozoic forams are known as fusulinids. Named for their fusiform shape, they are the shape and size of large rice grains. Entire layers of Pennsylvanian limestone formations are composed of their test remains. Later in Earth history, after the dinosaurs go extinct, giant forams become common once again as the nummulitids. The Cenozoic limestone that was used to build the pyramids in Egypt is packed with nummulitid foraminifera. These nummulitid forams can reach spectacular size for a unicellular organism (Cushman 1918). Their name means coin‐like, and indeed they can reach the size of a quarter (United States twenty‐five cent coin) or even larger in some cases. Foraminifera have provided some spectacular examples of convergent evolution, and even cases of repeated convergence called iterative evolution. Iterative evolution is a type of convergent evolution in which a basic, ancestral, or parent stock gives rise to successive groups of taxa (families, genera, species, etc.). Each new wave of taxa generally replaces the one previous, which oftentimes has been the victim of the latest extinction event. Salfeld in 1913 provided an early formulation of the concept of iterative evolution (Salfeld 1913). He hypothesized that two predominantly deep‐marine, evolutionarily convergent cephalopod groups (the Phylloceratina and Lytoceratina, respectively) gave rise respectively to shallow water and relatively short‐lived taxa that had been grouped together as the Ammonitina. The Ammonitina group is now known to be polyphyletic, that is, derived from multiple parent lineages rather than from a single stem group as would be 62 the case with a monophyletic taxon. K. Beurlen (known for discovering the cloudinid fossils in South America, McMenamin 1998) in a 1929 study on convergent and iterative evolution in crabs and their relatives, popularized the terms “conservative stem” and “iteration” in his description of the repeated occurrence of particular morphologies in successive offshoots of a particular group. Beurlen’s usage of iteration can be traced back to the iterative “Artenbildung” concept of Koken. In the 1930s, Kaufmann identified four successive lineages of the Upper Cambrian trilobite genus Olenus in Late Cambrian rocks of Sweden (Hoffman and Reif 1994). Three of the four lineages showed convergent morphological change, with, for example, elongation of the pygidium (tailpiece) occurring in all three lineages. The shallow water stratal sequences between each of the layered sequences that record the three lineages are barren of trilobites, suggesting that a local extinction event cleared this habitat and prepared the way for the next burst of iterative evolution. A. R. “Pete” Palmer has noted similar iterative patterns in Upper Cambrian pterocephalid and elviniid trilobites, unrelated to Olenus, in the Great Basin and Range of western North America. Hoffman and Reif (1994) felt that Kaufmann’s sample size was too small to unequivocally support the hypothesis of iterative evolution for Olenus, but nevertheless they allowed that this was an extremely important paper for macroevolutionary studies. Once frequently cited as a classic example of iterative evolution, evolutionary trends in the Mesozoic oyster Gryphaea have been reassessed. This thick‐shelled clam, with one larger, coiled valve, was once prized in northeastern England to be a folk remedy for rheumatism. George Gaylord Simpson claimed in 1944 that “repeated trends toward coiling in a plane (Gryphaea) or spiral (Exogyra) . . . appeared in oysters separately arising from a long ranging, relatively flat, Ostrea‐like stock.” Simpson continued this idea with the following comment (1961, p. 183): The gryphaeas, mentioned in discussing oriented evolution, are a good example. They represent several parallel developments from the same continuing oyster stock (Ostrea). The end results are in each case so similar that they are commonly considered as collectively forming a single group, Gryphaea, although they can be distinguished and do have separate origins within Ostrea. Both Gryphaea and Exogyra belong to the same bivalve family, the Gryphaeidae. Incidentally, a century ago zealous proponents of the concept of orthogenesis claimed that the increasingly coiled shape of Gryphaea eventually prevented closure of the shells. When taken to extremes, orthogenesis postulates an evolutionary momentum of some sort that actually carries evolutionary trends to the point where they become fatally maladapted (typostrophy), leading to extinction of the entire lineage! This is an anti‐Darwinian concept to be sure, but it is hard to imagine what forces would lead a particular lineage to change its morphology in a trend or in a direction that leads inevitably to destruction, unless one were to contemplate accelerating change in series of ancestor‐descendant morphogenetic torus species changes that led to maladaptive body form. I am not advocating this particular idea. 63 Stephen Jay Gould “straightened out” the Gryphaea orthogeneticists in 1972 by disclosing that negligence in fossil preparation was the source of the problem. It turned out that matrix had been left beneath the umbo of a particularly well‐known specimen, and that this matrix chip was obscuring the true shell structure. Anthony Hallam and Stephen Jay Gould (Hallam and Gould 1975) went on to show that Gryphaea actually had a continuous rather than an iterative evolutionary history (Gould 1980). In discussing whether evolution in Gryphaea was gradual or punctuated, Hallam and Gould (1975) conceded that “the evidence can be held to support both phyletic gradualism and punctuated equilibrium.” The “pseudo‐iterative” pattern of Gryphaea is partly a result of geographic migrations of two successive lineages from a main evolutionary center in central Europe, eventually resulting in a predominantly boreal distribution of these oysters throughout the world. Thus, although Gryphaea did not arise repeatedly by iterative evolution from a normal oyster stock, geographically distinct lineages arose from a central European locus. There seems to be an ecological signature to gryphaeid morphology (Hallam and Gould 1975). For instance, conventional ostreid oysters are opportunistic, preferring stressed marine environments, whereas gryphaeids live in stable, higher diversity marine environments. Thus an iterative pattern would not be unexpected for a case in which, say, ostreid oysters invaded a stable and high diversity marine community. Although they rejected the concept of ostreid to gryphaeid iterative evolution, Hallam and Gould (1975) noted two and possibly three trends that struck them as “little short of remarkable.” The trends involve the Late Jurassic transition from Gryphaea arcuata to Gryphaea gigantea, the Middle Jurassic transition from Gryphaea bilobata bilobata to Gryphaea dilatata dilatata, and the Cretaceous transition from earlier (Albian‐Cenomanian stage) gryphaeids to the latest Cretaceous genus Pycnodonte (an oyster, no relation to pycnodont fish). The trends in all three lineages included size increase (“Cope’s Law” of evolution, first articulated by dinosaur hunter Edward Drinker Cope), shell broadening, and reduction of the sulcus (the valve furrow). Pierre Teilhard de Chardin reported a quite similar type of pattern between 1942 and 1950 in Chinese fossil mole rats (McMenamin 1998; Matthews et al. 2007). The trends that Teilhard identified in several lineages included larger size (Cope’s Law again), fusion of cervical vertebrae (helps with burrowing), and increased hypsodonty or tooth elongation. Teilhard, as the first modern, western paleontologist to reject natural selection as the sole driving force of evolutionary novelty, slyly remarked in connection with the fossil mole rats that “Reste à trouver la bonne explication,” which may be translated as “The true reason remains to be seen.” Teilhard’s friend G. G. Simpson, true to his selectionistic biases, grew rather aggravated with this comment and huffily remarked that “increase in size of individuals (Cope’s Law) occurs when and while such increase is adaptive, and at no other times” and “the trend toward hypsodonty occurs in animals that eat especially fibrous, siliceous, or gritty food.” Teilhard (1943) is not taken in for a moment by Simpson’s pan‐selectionism, noting that Simpson’s “intransigent neo‐Darwinist attitude” has the considerable weakness of depriving the “evolutionary process of all direction and all significance.” 64 Heteromorphic ammonites are ammonites whose shells coil or otherwise grow in an irregular fashion. We see drastic departures in these cephalopods from the familiar and beautiful spirals of ordinary nautiloids and ammonites. Some of these heteromorphic forms, like Nipponites, end up looking like a tangled ball of rope (Okamoto 1996). Others, like Polyptychoceras, end up looking like the products of a mad pretzel baker. Seilacher and Gunji (1993) rightly note that this type of heteromorphic growth raises basic logical problems for theoretical morphology in terms of “final causes,” as in, why on earth did these mollusks take on such bizarre shapes? Seilacher and Gunji (1993) suggested that the open coiling of some of these forms might be “explained by soft‐bodied symbionts growing around the shell,” but this is by no means certain. In any case, heteromorphic ammonites were an evolutionary success, with representatives occurring as widely distributed as Antarctica, where a major heteromorphic ammonite assemblage has been described (McArthur et al. 2000), including the genera Ainoceras, Eubostrychoceras, Pseudoxybeloceras and Ryugasella. Josh Wiedman, in his 1969 work on irregularly (and sometimes bizarrely) coiled heteromorphic ammonites, delivered a blow to Schindewolf’s extreme orthogensis concept of typostrophy, namely, overspecialization to the point of extravagance and racial senility, leading eventually to extinction. Wiedeman admitted, however, the peculiarity of “the disconnected and iterative origin of heteromorph shells.” In his view, after an initial coiling from a straight shelled cephalopod ancestor in the Devonian, Wiedeman saw various ammonoid lineages uncoiling and ‘re‐coiling’ as many as four times before the end of the Cretaceous when ammonoids do go extinct. Wiedman went so far as cautioning against too strict an interpretation of “Dollo’s Law” (the irreversibility of evolution, that is, organisms cannot evolve back into ancestral stages), since an almost perfect reversion is shown by the return of the Cretaceous heteromorphs to the quadrilobate primary structure of the Triassic meso‐ammonoids. Wiedman claimed this as a ‘reverse mutation’ occurrence: “the sudden transformation of Cretaceous heteromorphs as a kind of spontaneous reverse mutation which recapitulated early phylogenetic stages—the primary shell coiling in the Devonian and ceratiid primary suture—with differing accuracy.” This does represent a rather profound violation of Dollo’s Law, and might better be addressed from the standpoint of morphogenetic considerations, particularly of the type that could potentially direct convergent (and by extension, iterative) evolution. Weidman claims adaptive significance for the gradual uncoiling reversion of Triassic and Jurassic heteromorphic ammonites, perhaps as an adaptation to benthic modes of life, although morphogenetic considerations have been invoked to explain the adaptive significance of ammonite heteromorphy (Seilacher and Gunji 1993). It is indeed interesting that the older (Jurassic) heteromorphs would show gradual, supposedly adaptational reversion whereas the younger (Cretaceous) heteromorphs appear to show more rapid, heterochronous reversion. Weidman attributes this to mediation by the “interplay between mutation and selection only.” But we must now reject this pan‐selectionistic perspective. The morphogenetic potential of the cephalopod hypertorus must now be taken into consideration when considering the heteromorphic cephalopods. 65 Many would agree that selection and adaptation can produce phylogenetic trends such as increase in individual body size (Cope’s Law) or, more generally, any convergent morphological feature (Teilhard’s Law). What about phyletic trends recurring in several related lineages, or iterative projections from within a single lineage? Many of these trends involve pronounced organismal change in a punctuational sense, as we will see further in the case of foraminifera. Does this mean that macroevolutionary change can strike twice or more in the same place? Let’s now consider the radiations of foraminifera (informally known as forams) at the beginning of the Cenozoic (Paleocene Epoch) and in the Neogene (Miocene Epoch). Twice, from generalized globigerinoid foram stock, we see the evolution of, first, globigerinoid forms. Second, we see an evolutionary series running from turborotalid to globorotalid to conical forms. Third is the appearance of what are called hastigerine and orbuline forms. Cifelli (1969) has these strikingly similar morphologies apparent in the fossil record on either side of the Oligocene epoch; two global marine microbiotas, different, and yet the same. Once again, this seems to be somewhat too ordered a pattern to be accounted for solely by selectionistic adaptation driven by random mutations. Russian paleontologist A. Rozanov in 1963 detected a similar convergence pattern in the Early Cambrian sponge‐like archeocyaths. Archeocyaths show a complex pattern of isochronous trend parallelism in five lineages: Monocyathidae, Dokidocyathina, Coscinocyathina, Ajacicyathina, and Nochoroicyathina. The convergent traits, in order of occurrence in each lineage, are as follows. First, we see forms with simple walls. Second, forms with ethmophyllid‐like inner walls appear (Figure 1.2). Next, forms with outer wall tumuli are seen. Fourth, forms with reticular outer walls appear. Finally, and fifth, is the appearance of forms with additional outer wall membranes. Not all of these traits occur in all five lineages, but the fact that they always occur in the same relative order as shown is telling us something interesting. In fact, it provides more evidence for the archeocyath morphogenetic field transformations discussed in an earlier chapter. The fact that these evolutionary changes were not synchronous (as is also the case with Cifelli’s [1969] forams) negates an explanation that relies exclusively on precise adaptation to identical local environments. How might we go about explaining iterative evolutionary patterns? We might say that the iterated patterns observed are a direct result of an organism’s pre‐existing potential for change, or if you will, its inherited evolutionary flexibility. For a given, presumably stable environment conducive to expression of evolutionary trends, related lineages, whether through developmental heterchrony or other factors, have a good likelihood of discovering (or even rediscovering) ways to populate available habitats. Similar morphogenetic systems, given similar modes of change and similar environmental stimuli, can be reasonably expected to respond in similar ways. The consistent ordered appearance of trait succession in different but related lineages indicates that some morphological changes have lower “evolutionary thresholds,” leading to their favored appearance and thus have a greater probability of appearing before other, less likely morphological changes. For example, it is “easier” to evolve globigerinoid forams from globergerine forams that it is to derive hastigerines from them. Hence, globigerinoid 66 forams appear before hastigerines in the iterative sequence. Both may involve relatively straightforward morphological changes, but one may be more likely than the other. In a follow‐up to Cifelli’s (1969) research, my undergraduate research student Aimée L. MacEachran (1996) completed a study for her honors thesis that showed simultaneous iterative evolution in two unrelated foraminiferal lineages with completely different skeletal compositions. Her research sent out shock waves that were felt throughout the world of evolutionary studies, for it challenged the view that convergent evolution results from pressures of natural selection only on fairly closely related forms. I mark her results, which she completed in a fairly short burst of intense research in fall 1995, as the time when I first began to get really interested in examining the widening, soon to be fatal cracks in the foundation of the Modern Synthesis. Not bad for a Mount Holyoke College undergraduate thesis. While studying the giant trilobite Torolenimorpha longa, petrographic thin sections of the rock matrix revealed that the fossiliferous limestone was packed with tiny fossils. Ordovician foraminifera had been reported from Virginia before (Moore 1952), but they were of agglutinated types rather than the calcareous forms described here. These fossils of calcareous Ordovician foraminifera are of otherwise unfamiliar types and thus represent an exciting new discovery. Like the trilobite, these are Middle Ordovician in age (early Caradocian) and from the Effna Formation. Illustrated in Figures 9.1‐9.7, and described in Appendix A, these forams represent a previously unknown microbial marine fauna morphology that was lost, and then reappeared by convergent evolution much later. The swarm of new genera described here includes Foram species A (Figure 9.1), Foram species B (Figure 9.2), Foram species C (Figure 9.3), Foram species D (Figure 9.4), Foram species E (Figure 9.5), Foram species F (Figure 9.6) and Foram species G (Figure 9.7). These are all morphological counterparts, or evolutionarily convergent precursors to the later foraminifera genera Pleurostomella, Calcitornella, Triloculina, Orbulina, Spiroloculina/Cornuspira, Renulina and Howchinia. 67 Figure 9.1. Foram species A. The fossil is conical in shape, with the apex of the cone to the left. Chamber walls are seen as curved lines on either side of the central tube. The fossil is preserved in a lime mud matrix. Petrographic thin section slide 1 of 4/11/08. Length of test approximately 0.5 millimeter. Figure 9.2. Foram species B. The fossil is preserved in a lime mud matrix. Petrographic thin section slide 1 of 4/11/08. Diameter of section approximately 100 microns. 68 Figure 9.3. Foram species C. Petrographic thin section slide 1 of 4/11/08. Diameter of test approximately 100 microns. Figure 9.4. Foram species D. Greatest dimension of fragment of cracked outer test on right approximately 150 microns. Petrographic thin section slide 1 of 4/11/08. Linear structure on left side is an unrelated shell fragment. The fossil is preserved in a lime mud matrix. 69 Figure 9.5. Foram species E. The fossil is preserved in a lime mud matrix. Petrographic thin section slide 1 of 4/11/08. Greatest width approximately 250 microns. Figure 9.6. Foram species F. Note flat underside of test. The fossil is preserved in a lime mud matrix. Petrographic thin section slide 1 of 4/11/08. Greatest width approximately 250 microns. 70 Figure 9.7. Foram species G. This is a coiled foram; the apex of the test is to the right. The fossil is preserved in a lime mud matrix. Petrographic thin section slide 1 of 4/11/08. Greatest dimension of specimen 150 microns. The cross‐sectional shape of Foram species A is rather reminiscent of that of a tiny straight nautiloid cephalopod, complete with curved septa and what appears to be a siphuncle‐like structure (Figure 9.1). But instead of the structures resembling the track left behind by a torus in motion, leaving curved septa and a cylindrical core in its wake, the structure of this and other forams is formed incrementally, by accretion of structures called chambers. As such, forams share a modular or metacellular mode of growth, as seen in certain Ediacarans (McMenamin 1998). Foram species B (Figure 9.2) has a central cylinder but is also formed by chambering. Foram species D (Figure 9.4) forms a globular chamber with a thin shell covering its surface, and it reproduces by generating smaller copies of the cell within. The outer test evidently cracks to release the progeny. This exciting new foram biota has well developed diversity, and also has a representative of Cifelli’s (1969) orbulinid morphology, hence it should be considered as comparable to the third of the three steps in the sequence of foraminiferal radiation involving iterative evolution as described by Cifelli (1969) for the Cenozoic evolution of forams. This is hugely important for evolutionary studies, for it adds to the growing sense among experts that there is a certain predictability to the evolutionary process. 71 Chapter 10: Summary and Conclusions WE MAY CONCLUDE from the foregoing that the toroidal theory does not explain all of complex biotic form, particularly for some groups of protists such as forams, but nevertheless evolutionary convergence is to be expected for all growth modes regardless of their dynamic patterning, that is, be they toroidal, metacellular, chambered, etc. Convergence therefore has a distinct morphogenetic character. As Hermann Poppelbaum put it in A New Zoology: “A morphological pattern, after having found expression at some earlier period, may disappear for a long while and then be taken up and further evolved by organisms of an unrelated stock.” Vendoglossa tuberculata is essentially an overgrown gastrula, a fossilized multi‐torus (Jockusch and Dress 2003) that has preserved as a series of transverse bands formed originally as circular buckles that spontaneously formed on the surface membrane as in Plate 34 of Pivar (2004). What a perfect counterpart, then, it makes with the ablastulate metacellular Ediacarans (McMenamin 1998). We see here two simple and yet “cheap” ways to attain centimeter size in an ad hoc, largely experimental fashion. The Proterozoic time should be recognized for what it is, an age of experimental morphogenesis. And morphogenesis should be recognized as not merely as a product of some genetic blueprint. As Ian Stewart (1998) put it, “This means that you cannot understand gastrulation in purely genetic terms. You must build in the mathematics of buckling too, or more precisely, you must build in whatever analog of buckling applies to the material of a blastula.” The individual cells of the blastula are called blastomeres, and they retain both a holograph‐like sense of the entire embryo, and information relating to their position within the embryo. It is this information that gets shifted and deployed during toroidal streaming. In contrast, the individual units of a metacellular Ediacaran or a foram are called metacells (chambers) or ablastomeres. They form buds, in a process known as iterative growth, building up a body as a united collection of metacells or chambers, respectively. We see here two fundamentally different growth patterns, one blastulate, the other ablastulate, but both responding, within their respective morphogenetic fields, to dynamic constraints of development as it proceeds. Denton and Marshall (2001), writing in Nature, understand what this means: It will mean that physical laws must have had a far greater role in the evolution of biological form than is generally assumed. And it will mean a return to the pre‐Darwinian conception that underlying all the diversity of life is a finite set of 72 natural forms that will recur over and over again [read here: convergent evolution] anywhere in the cosmos where there is carbon‐based life. We have here then a new theory of evolution, and we can now ring in the bells of a newer and truer synthetic theory of biological science. This new theory has vast implications and is fully consonant with the most cogent strands of our best philosophy. Former areas of conflict can now be resolved. Stephen Jay Gould (1977) was right about the problematic nature of pan‐selectionism, and yet at the same time his critics are quite right to emphasize the fact that convergence speaks to the inevitable repetition of rather specific morphologies. This new level of understanding elevates our entire mode of evolutionary discourse. For example, we can begin to see just how many wasteful arguments have been started by what Pivar (2004) has called “Darwin’s oversimplified idea.” At first glance microevolutionary change seems easier to explain than the genesis of form or macroevolution. But this may not necessarily be the case. And evolutionary rates in both cases can be anything but gradual. The big transitions seem to happen fast, as fast as the smaller transitions. This can be particularly so at the time of emergence of new challenges across the environment such as increases in oxygen or the appearance of large predators (McMenamin and McMenamin 1990). Such cases can trigger vast and global developments that restructure the biosphere. The global changes trigger what Goodwin (1994) called morphological transitions: “The morphological transitions are the consequences of the cycle of dynamics generating geometry and geometry modifying dynamics.” We are looking here of course at a gigantic feedback loop, because the global changes themselves are set into motion by morphological advances. Some would say, and I would agree, that these are inevitable morphological advances. Geometrical constraints can thus specify, and perhaps even allow us to predict, the course of evolution of a biosphere. The Cambrian Explosion, for instance, involving as it did so many toroidal phyla following convergent evolutionary pathways, may have been encoded into biospheric development from the very beginning. Even the larvae of the Cambrian phyla, as Stuart Pivar suggests, show striking convergent features. We are left then, with one final problem. We see how the mechanics of modifying the morphogenetic toroidal field can modulate the form of organisms. But what causes this to occur? I no longer see natural selection as playing any kind of role in generating or even guiding the origin of biological novelty. So, whence does this novelty come? We have definitely entered a post‐Darwinian era, for to answer this question we must appeal to pre‐Darwinian thought, nicely articulated here by Early American geologist and president of Amherst College Edward Hitchcock (1849): [God] intended the world ultimately to become the residence of intellectual and moral beings: but for wise reasons he chose to bring it by slow processes of change into a fit condition for their residence. Yet his overflowing benevelence prompted him to people the world, during this transition state, with animals whose natures were perfectly adapted to its condition. And as often as that condition changed, did 73 he change its inhabitants and their constitution. He might have left it desolate during these mighty periods of preparation. But infinite benevolence would not permit. For Hitchcock, who was an implacable foe of Darwinian evolution by natural selection (and as right here as he was right about many other things), the Earth changed slowly but its inhabitants changed fast, marked by the sudden appearance of animals whose natures were perfectly adapted to ambient conditions. I hereby suggest, in accordance with Hitchcock's comment, that each new species appeared as a result of a Divine reconfiguration of the embryonic morphogenetic field and/or its morphogenetic torus. The new creatures, created as a small population in accordance with the requirements of the environment into which they were placed, represent a special creation of kind that lived for its allotted span and then perished, giving way to newer forms. The origin of species is thus decidedly saltational and punctuational. The same may be said for the origin of phyla. Convergent evolution really represents a creation in stages, so to speak, where each lineage with each successive step approximates, by Divine fiat, and via each new species, more closely to some idealized form (dove, sheep, human, etc.). Why God did not simply make the ideal forms at the outset is unknown, but we might speculate that it served Divine will and pleasure to populate the mighty periods of preparation. Besides, the majestic historical narrative generated as a byproduct also helped to prepare the earth for the eventual advent of intellectual and moral beings who, we might hazard to say, also appeared on the scene rather suddenly. 74 Acknowledgments I WISH TO gratefully acknowledge the assistance of Gerard Marchand, Dianna L. Schulte McMenamin, Sarah Kelly McMenamin, Suzan Mazur, Stuart Pivar, Katherine Malone, Buckminster Fuller, Ann Marie McMenamin, Haeinn Woo, Dolf Seilacher, Hans Luginsland, Lynn Margulis, Meredith Peters, Steve Rowland, Melanie Gibson, Sarah Beth Cadieux and Jessica Marie McMenamin. Special recognition is due to Dolf Seilacher for his epochal 1993 expedition to Namibia (see McMenamin 1998). The 2008 field expedition to the Cambro‐Ordovician rocks of the El Paso area was supported in part by a faculty research grant from Mount Holyoke College. 75 Appendix A: Systematic Paleontology Kingdom PROTISTA Phylum SARCOMASTIGOPHORA Class GRANULORETICULOSEA Order FORAMINIFERIDA Family incertae sedis Genus incertae sedis Foram species A (Figure 9.1) Diagnosis. Calcareous elongate test, biserial and imperforate with a presumably originally hollow tubular structure between the narrow apertures of successive chambers. Occurrence. Float sample from the Effna Formation, presumably collected in Virginia, United States. Provenance not certain. Material. Petrographic thin section slide 1 of 4/11/08. Age range: Middle Ordovician (early Caradocian). Family PARATHURAMMINIDAE Genus incertae sedis Foram species B (Figure 9.2) 76 Diagnosis. Globular calcareous test, hyaline but now recrystallized, early part tightly coiled, later part with long, loosely coiled chambers. Ornamentation on test surface consisting of bluntly terminated protuberances that may have originally been tubular and hollow. In thin section, alternation of up to five wall layers alternating light and dark is visible. Figure 9.2 shows columns that may have once been protuberances linking the inner and outer light walls. Discussion. Foram species B bears resemblance to the Ordovician‐Carboniferous foraminiferan Parathurammina. Parathurammina, however, evidently lacks the alternation of light and dark wall layers seen in Foram species B. The tubular projections in Parathurammina appear to be hollow (Sabirov and Gushchin 2006) and this may have originally been the case for Foram species B as well, with sparry calcite now filling the tubes. Foram species B also bears resemblance to the Devonian parathuramminid genus Saltovskajina Sabirov. Like Foram species B, Saltovskajina shows alternation of light and dark wall layers, but appears to have fewer layers than Foram species B and also appears to have a much thicker outer wall and a more irregular test outline. Some researchers have questioned whether members of the Parathuramminida should be classified as foraminifera or as radiolaria (Vishnevskaya and Sedaeva 2002; Sedaeva and Vishnevskaya 2003). Foram species B belongs to a group of homoplasic (evolutionarily convergent) foraminifera that include the Pennsylvanian to Permian calcareous forams Calcitornella and the agglutinated Ammovertella. These forams represent cases of homoplasy comparable to those described by MacEachran (1996). Occurrence. Float sample from the Effna Formation, presumably collected in Virginia, United States. Sample 1 of 4/11/08. Provenance not certain. Material. Petrographic thin section slide 1 of 4/11/08. Age range: Middle Ordovician (early Caradocian). Family incertae sedis Genus incertae sedis Foram species C (Figure 9.3) 77 Diagnosis. Calcareous test with early chambers globergerine, later ones added in planes 120° apart from one another, so that the exterior of the test is composed of three or four chambers. Discussion. Foram species C is considered here to be evolutionarily convergent with the Triassic‐Recent (Cushman 1928) genus Triloculina. The Eocene foram Sphaeroidina austriaca D’Orbigny also has a similar test morphology to Foram species C, but the Eocene species has an apparently greater rate of chamber expansion (Cushman 1935). Occurrence. Float sample from the Effna Formation, presumably collected in Virginia, United States. Sample 1 of 4/11/08. Material. Petrographic thin section slide 1 of 4/11/08. Age range: Middle Ordovician (early Caradocian). Genus incertae sedis Foram species D (Figure 9.4) Diagnosis. Calcareous spherical test, eggshell‐like thin non‐porous outer test wall. Reproduction by internal proliferation. Discussion. Foram species D is spherical like the Ordovician foraminiferan genus Bisphaera, but apparently lacks a porous wall structure (Sabirov and Gushchin 2006). Foram species D in this example has evidently been caught in the act of releasing progeny, seen as small spherical tests coming out from the broken parent test. The new taxon bears considerable resemblances to Orbulina universa, but the progeny tests apparently lack the spiny surface of O. universa (Cifelli 1969). Occurrence. Float sample from the Effna Formation, presumably collected in Virginia, United States. Sample 1 of 4/11/08. Material. Petrographic thin section slide 1 of 4/11/08. Age range: Middle Ordovician (early Caradocian). Genus incertae sedis 78 Foram species E (Figure 9.5) Diagnosis. Calcareous, hyaline discoidal test consisting of a long, panispirally coiled presumed second chamber. Discussion. Foram species E is evolutionarily convergent on the ?Carboniferous‐Recent (Cushman 1928) genus Cornuspira. Foram species E. can also be considered to be convergent on the Upper Triassic‐Recent Spirulina vivipara Ehrenberg (Margulis and Brynes 1999). There is also a strong morphological resemblance between Foram species E and Ammodiscus glabratus Cushman and Jarvis; the latter species however is agglutinated, not calcareous (Israelsky 1951). Occurrence. Float sample from the Effna Formation, presumably collected in Virginia, United States. Material. Petrographic thin section slide 1 of 4/11/08. Age range: Middle Ordovician (early Caradocian). Genus incertae sedis Foram species F (Figure 9.6) Diagnosis. Calcareous test with adult chambers becoming “C”‐shaped with somewhat swollen ends. One side of the test is straight, with a series of curved chambers forming the opposite side. Discussion. Foram species F somewhat resembles the Eocene species Renulina opercularia Lamarck, but is narrower and less obviously kidney‐shaped. There is also a faint resemblance between Foram species F and the Upper Eocene foraminiferan Sigmoidella plummerae Cushman and Ozawa in terms of one edge of the test being relatively flat. In Sigmoidella plummerae, however, the test is asymmetric and tapers to one side (Cushman 1935). Occurrence. Float sample from the Effna Formation, presumably collected in Virginia, United States. Sample 1 of 4/11/08. 79 Material. Petrographic thin section slide 1 of 4/11/08. Age range: Middle Ordovician (early Caradocian). Genus incertae sedis Foram species G (Figure 9.7) Diagnosis. Calcareous trochoid test, consisting of a single compressed spiral chamber; umbilicus projecting as a blunt dome. Discussion. Foram species G differs from the Carboniferous species Howchinia bradyana (Howchin) by having a projecting rather than a depressed umbilicus, but is otherwise rather similar (Cushman 1928). Occurrence. Float sample from the Effna Formation, presumably collected in Virginia, United States. Material. Petrographic thin section slide 1 of 4/11/08. Age range: Middle Ordovician (early Caradocian). Kingdom ANIMALIA Superphylum ECDYSOZOA Phylum ARTHROPODA Class TRILOBITA Order incertae sedis Superfamily incertae sedis Family incertae sedis 80 Genus Torolenimorpha nov. Diagnosis. A very large olenimorph trilobite with more than sixty pleural segments and a large glabella with a smooth profile except along the glabellar margin where the anteriormost segmentation laps onto the edge of the glabellar margin. Anterior margin of glabella semicircular. Pleural segments relatively narrow, with a rumpled texture suggestive of weak mineralization. Anterior part of cephalon, librigenae, and pygidium unknown. Description. This large olenimorph trilobite has a preserved length of 115 mm and a maximum preserved width of 57 mm. The maximum width of the carapace was approximately 68 mm in life. The glabella is preserved at one end of the axial lobe; as many as 40 pleural segments are visible. As there is no significant taper to the trilobite’s thorax as preserved here, it seems likely that the complete animal might have had as many as 100‐ 120 pleural segments total. Adding to this the saggital dimension of the cephalon, the complete trilobite might well have been in the vicinity of 350‐400 mm in length, and a total body length approaching a half meter or more in total length would not be out of the question. The cuticle of the carapace of this trilobite seems remarkably thin and flexible considering the animal’s size. The cuticle bulges and wrinkles in a way that suggests weak, or even no, mineralization. Age range: Ordovician. Geographic distribution. Known only from Eastern North America. Torolenimorpha longa n. g. n. sp. (Figures 4.1, 4.3) Diagnosis. As for genus. Discussion. As noted above, the cuticle of this trilobite seems rather thin and lumpy on close inspection. This unique trilobite has a very gradual apparent taper to its body form, and this might imply an overall body length in the vicinity of 35‐40 centimeters. Torolenimorpha longa n. g. n. sp. is a possible descendant of the somewhat similar, unnamed Cambrian olenimorph trilobite referred to in McMenamin and Weaver (2004) as “ptychoparioid genus and species A.” Occurrence. Float sample from the Effna Formation, presumably collected in Virginia, United States. Material. Sample 1 of 4/11/08. Repository. Mount Holyoke College paleontology collection sample number 8947. 81 Age range: Middle Ordovician (early Caradocian). Phylum ?NEMATODA Class incertae sedis Order incertae sedis Family incertae sedis Genus Vendoglossa Seilacher 2007 Diagnosis. A dorso‐ventrally compressed stem group metazoan, with a large gut cavity and annulated or ridged outer surface. The overall shape of the animal delineates a flattened toroidal membrane. Vendoglossa tuberculata Seilacher, 2007 (Figure 2.1) Diagnosis. As for genus. Description. Length of specimen 3.8 cm; width 2.4 cm. Preserved end is presumed to be the anterior end of the animal. This end comes to a tapered yet blunt termination, with a slight downward bend and a dimple or indented area posterior to this. More than 25 annulations are visible along the length of the animal, all perpendicular to the midline; each annulation approximately 1 mm in width. Central cavity, as shown by impressions made by its outer edges, is 10 mm wide at greatest width, and tapers in both anterior and posterior directions. Discussion. The preserved end of this specimen is presumed to be anterior, hence the downward projection at the tip and the dimple are interpreted here as a mouth‐buccal cavity complex. The detail shown in Figure 2.1 is due to a newly developed staining technique (using dark wood stain) for bringing up contrast in a painted fiberglass cast of the actual specimen. The animalian, and possibly nemade, affinity suggested here for Vendoglossa tuberculata stands in striking contrast to the metacellular and particularly iterated metacellular character of other Ediacarans (McMenamin 1998). For example, the Ediacaran Solza margarita, with its bifurcating ridge system, represents the single metacell equivalent 82 to the double metacell form Gehlingia dibrachida and the trifold metacell forms Albumares brunsae, Anfesta stankovskii and Tribrachidium heraldicum. Seilacher (2007:396) suggested an infaunal habitat for Vendoglossa tuberculata, suggesting that it perhaps lived just beneath the biomat film at the sediment‐water interface. Age range: Late Proterozoic, Ediacaran (Vendian or Lipalian) Period, approximately 567 million years old. Occurrence. Nama Group, Pteridinium sandstone, Aus Plateau, Namibia. Material. The original specimen is unnumbered and is kept in the paleontology collection on the Erni farm, Namibia. Geographic distribution. The taxon is currently known only from the Kalahari Craton, Namibia, southwest Africa. Phylum MOLLUSCA Class CEPHALOPODA Subclass NAUTILOIDEA Order ELLESMEROCERIDA Family ELLESMEROCERATIDAE Genus incertae sedis Diagnosis. An orthocone nautiloid with a slightly bulging apex, wide, ventrally‐displaced marginal siphuncle, gently curved early septa that give way to straight, oblique late sutures, ellesmerocerid ectosiphuncular structure (hemichoanitic septal neck sections [Figure 2 in Flower (1964)]), laterally compressed (Figure A.1) orthocone intermediate in width as in Eremoceras (Flower 1964, his Figure 8, p. 40). Comments. Ellesmerocerid research has been hampered by the difficulty of making comparisons between specimens preserved by the two primary modes of preservation, namely, silicification and preservation in limestone (Furnish and Glenister 1964). Overall conch morphology is well preserved by silicification, whereas details of ectosiphuncular structure are best seen in specimens preserved in limestone. Although Nautiloid species A is a monotypic taxon, the type specimen has the advantage of revealing both conch profile (Figure A.1) and internal structure (Figures A.2‐A.3). 83 Eremoceras (See Flower 1964, his Plate 10, Figure 1) differs from Nautiloid species A primarily by having curved late septa and thick siphuncular rings. Similarities in ectosiphuncular structure shows that Nautiloid species A has affinities to ellesmeroceratid nautiloids Clarkoceras and Dakeoceras. Although diaphragms are typically present in the large siphuncles of Clarkoceras (Furnish and Glenister 1964), no diaphragms are seen in the siphuncle of Nautiloid species A. The profile of Nautiloid species A differs substantially from that of later straight nautiloids such as Trematoceras from the Triassic of northern Italy (Engeser 1996, figure 4c), where the outer wall is a relatively smooth curve. Nautiloid species A, in fact, seems to resemble in overall form the ammonitella region of the ammonoid Pseudobactrites and, if one ignores the planispiral coil, Mimagoniatites, in both of which (Landman et al. 1996, figures 2A‐B) there is a bulbous initial chamber (as in Figure A.2 for Nautiloid species A) followed by a constriction, a straight interval, and then a second constriction and then rapid expansion as seen also in Figure A.1 (left side) and Figure A.3 for Nautiloid species A. All this suggests that Nautiloid species A may very well be the stem group taxon for the ammonoids, not an unreasonable conjecture considering the basal taxonomic position of the Ellesmerocerida. Nautiloid species A (Figures A.1‐A.3) 84 Figure A.1. Nautiloid species A. Field photograph. Specimen occurred in stratigraphically exactly placed roadside float. Scale bar in centimeters. Note hypertorus bulge on both ends of this Ordovician straight nautilus shell. Figure A.2. Nautiloid species A. Polished vertical longitudinal section of apical end of shell, showing bulbous shell termination and large siphuncle. Ellesmerocerid ectosiphuncular structure visible along lower margin of siphuncle. Part of shell above siphuncle filled with sparry calcite. Sample 1 of 12/6/08. Scale bar in millimeters. Figure A.3. Nautiloid species A. Polished, approximately vertical longitudinal section of aperatural end of shell, showing septation representative of straight, oblique late sutures. Note the swarm of trace fossils (we might think of these as “toroid tracks”) in aperatural 85 matrix and sparry calcite filling fracture on the right. Sample 2 of 12/6/08. Scale bar in millimeters. Distribution. Known only from the southern Franklin Mountains, El Paso, Texas; samples 1‐4 of 12/6/08. Age and Stratigraphic position: Unit 4 (Appendix C), McKelligon Canyon/flank of Sugarloaf Mountain (LeMone 1976) section of the Florida Mountains Formation, Lower Ordovician (Lower Canadian). Order TARPHYCERIDA Family TARPHYCERATIDAE Genus Tarphyceras ?Tarphyceras sp. (Figure A.4) 86 Figure A.4. ?Tarphyceras sp. Photo taken from outcrop exposure; specimen was left in outcrop. Note heavily burrowed silty limestone matrix. Scale bar in centimeters. Description. This advolute coiled tarphycerid nautiloid is shown here (Figure A.4) in a field photo. The specimen was left in the field so as to not deface the outcrop ledge. The specimen is seen in a vertical whorl cross section of the planispiral conch, and shows somewhat irregularly curved septa in section and what appears to be a large protoconch as in Tarphyceras. Comments. Based on the close resemblance of early tarphycerids to the Upper Canadian bassleroceratid nautiloids (a type of ellesmerocerid nautiloid), the tarphycerids are considered to be evolutionarily derived from the ellesmerocerids (Furnish and Glenister 1964). Tarphycerids differ from bassleroceratids by being much more tightly coiled. Age and stratigraphic position. Unit 4 (Appendix C), McKelligon Canyon/flank of Sugarloaf Mountain (LeMone 1976) section of the Florida Mountains Formation, Lower Ordovician (Lower Canadian). 87 Appendix B: New Ellesmeroceratid and Tarphyceratid Nautiloids from the Franklin Mountains Area, El Paso, Texas (with Katherine Malone) A FRESH EXPOSURE of Lower Ordovician carbonates of the Florida Mountains Formation (Franklin Mountains, Texas) has produced new orthocone and advolute coiled nautiloids. Nautiloid species A is a moderate‐width straight nautiloid with affinities to the ellesmeroceratid nautiloids Clarkoceras and Dakeoceras, but representing an overall shell form that is convergent on the ellesmeroceratid genus Eremoceras. Nautiloid species A provides critical evidence bearing on the evolution of the ellesmeroceratids and the early evolution of cephalopods. Introduction The Southern Franklin Mountains of the El Paso area Texas expose a remarkable succession of late Cambrian and Ordovician strata. The first trilobite described from the southwestern North America (Emory 1859) was collected from a float sample derived from the El Paso group (Figure B.1). 88 Figure B.1. Asaphus emoryi Hall 1859, an asaphid trilobite collected from near El Paso, Texas, on the famous 1850s Emory expedition. USNM number 9824. This historic specimen, now in the Smithsonian Institution, was the first trilobite fossil reported west of the Mississippi. It is a fairly close relative of the giant trilobite Isotelus rex. Scale bar in centimeters. Asaphus emoryi Hall 1859 is an asaphid trilobite, but its species identity has been difficult to confirm because the cephalon is crushed. It may belong to the species Aulacoparia huygenae Flower 1968 (Flower 1968). The precise source bed of the Asaphus emoryi Hall 1859 is unknown, but it might possibly be derived from unit 26 of the measured section described here (Appendix C). The early Ordovician El Paso group of the Southern Franklin Mountains has yielded a diverse fauna of gastropods, nautiloids, trilobites, brachiopods, echinoderms, ribeiroid clams, monoplacophorans, and other conodonts (LeMone 1976; LeMone et al. 1988). Repetski (1982) reported the conodonts ?Spathognathodus, Oistodus cf. O. lanceolatus Pander, and Protopanderodus asymmetricus Barnes and Poplawski, a fauna that ranges from early to late Canadian. The oldest nautiloids in the succession occur in the “Lower Canadian portion” of Flower (Flower 1964). Flower (1964) complained about poor 89 preservation in this lowest interval but nevertheless reported the ellesmeroceratid genera Ectenolites (=Eromoceras), Ellesmeroceras, Dakeoceras, and Clarkoceras [as Clarkeoceras]. In his Figure 50 (Flower 1964), Flower recognized in the Franklin Mountains, El Paso sequence the following nautiloid intervals: a “Lower Canadian Portion,” a first endoceroid zone (base of the Middle Canadian), a first piloceroid zone, an oolite interval characterized by ?Rudolfoceras, and a reef interval characterized by Mcqueenoceras. LeMone (1976) listed the following genera as occurring in the Florida Mountains Formation: Catoraphiceras, Tajaroceras, Cyptendoceras, Rhabdiferoceras, Manchuroceras, Buttsoceras, Protocycloceras, and Michelonoceras. The new exposure of the Florida Mountains Formation on the flank of Sugarloaf Mountain flanking McKelligon Canyon has yielded important new fossils including orthocone and coiled nautiloids and a roadside float sample with more than 25 specimens of conspecific gastropods (Figure 22; evidently derived from unit 34 in Appendix C), about half of which may represent a single cohort of Hormotoma gracilis (Hall). Figure B.2. Hormotoma gracilis (Hall), an Ordovician gastropod cohort probably from unit 34 of the Florida Mountains Formation, McKelligon Canyon region, El Paso, Texas. Sample from roadside float, field sample number 1 of 12/5/08. The section is 13.13 meters in thickness. This compares closely with the 12.3 meters of section reported by LeMone (1976) from near the same site. LeMone’s section had many covered intervals, and is about half incomplete in comparison to our new, more complete section measurement. 90 New Ordovician Nautoloids The Ordovician is marked by a dramatic phase of nautiloid experimentation in shell form (Dastanpour et al. 2006). After their origin, in the late Cambrian, ellesmeroceratids underwent a dramatic radiation that gave rise to virtually all other nautiloid families (Flower 1964). One of these families is the Tarphyceratidae, a family that includes the earliest advolute coiled cephalopods. Convergent evolution (homeomorphy) is rampant in middle and upper Canadian nautoloids, but has been less noted in lower Canadian ellesmeroceratid nautiloids (Flower 1964). We remedy this paucity in part here with description of the new genus Nautiloid species A (homeomorphic in terms of external shell shape with Eremoceras) and a new report of ?Tarphyceras sp. Conclusions In a now famous paper published in 1966, David Raup defined what are now known as the Raupian Parameters (Raup 1966; Raup and Stanley 1978). These parameters specify the distribution of shell morphology in organisms with coiled shells, along three axes that include expansion rate (W), translation (T), and distance of generating curve from axis (D). Raup made effective use of emerging computer technology to plot the variations between helicoid, planispiral, and other shell forms (Raup 1966). Lesser known is the fact that Flower (Flower 1964) published in 1964 a morphometric diagram for ellesmeroceratid nautiloids that includes two of the three Raupian Parameters. Flower’s (1964, his Figure 8) slender‐stout axis is equivalent to W, the rate of whorl expansion, and Flower’s (1964) straight‐curved axis is analogous to D, the distance of the whorl from the coiling axis after one revolution. As far as we could ascertain, all of the ellesmeroceratid nautiloids considered by Flower (1964), and by Furnish and Glenister (1964), are planispirally coiled. Ogygoceras gracile, known from a single specimen and considered to be pathologic specimen because of its “gently sigmoidal” shape (Furnish and Glenister 1964), we consider to be not pathological but rather a ellesmeroceratid nautiloid that changed its growth mode from planispiral with high D to orthocone about halfway along the preserved portion of the shell. Flower’s (1964) Figure 8 represents the right vertical face of the morphospace cube for the Raupian Parameters (Raup 1966; Raup and Stanley 1978). Raup (figure 8‐7, page 177 in Raup and Stanley 1978) shows only a very narrow band (“B”) for coiled cephalopods, whereas Flower (1964) allows for a much greater diversity of expansion rates (W) in his nautiloids. Evidently Raup (1966) was not sufficiently aware of the more 91 breviconic (large W) ellesmeroceratid nautiloids, and neglected to include them in Raupian Parameter morphospace diagram. Future work in this area should acknowledge Flower’s (1964) anticipation of the Raupian Parameters. 92 Appendix C: McKelligon Canyon/Sugarloaf Mountain Freshly Exposed Section of the Florida Mountain Formation (pars), measured March 13, 2008 Figure C.1. Fresh exposure of silty limestones of the Florida Mountain Formation, El Paso, Texas. Note backpack and camera case in lower left for scale. Note: Section ends against fault; units listed in descending stratigraphic order. 37. 200 cm. Thin to medium bedded burrow mottled silty limestone. Several red (?) karsted (?) terra rossa zones. 36. 16 cm. Nodular (base) to thick‐bedded shell hash. Orthocone nautiloid near top 10 cm in length. 93 35. 69 cm. Medium bedded burrow mottled silty limestone. 34. 18 cm. Thin bedded silty limestone with shelly stringers filled with Hormotoma‐type gastropods and echinoderm calyx plates. 33. 117 cm. Thick‐bedded silty limestones. Beds approximately 20 cm thick. 32. 57 cm. Silty, medium bedded limestone, cherty in middle, top forms narrow bench. 31. 35 cm. Bedded nodular limestone, some grainy beds, Thallasinoides present. 30. 2.5 cm. Laminated (tidal‐influenced?) limestone. 29. 40 cm. Cherty. bluish limestone, chert in nodules and stringers. 28. 60 cm. Burrow mottled silty limestone, scattered shelly layers and narrow burrows. 27. 2 cm. Calcareous shale. 26. 20 cm. Burrow‐mottled silty limestone; shell hash/rudite beds up to 4 cm thick. Small brachiopods, crinoid pieces, possible pisolites. 25. 13 cm. Burrow‐mottled silty limestone, microlaminated in upper part. 24. 33 cm. Burrow‐mottled silty limestone, brachiopod rich, shell‐hash bed in center. 23. 22 cm. Limestone with up to 4 cm thick shell hash beds. 22. 30 cm. Burrow‐mottled silty limestone, cherty in lower half. Top of bed forms bench. Top of bed at ichnofacies level 4 ( ?Glossifungites ). 94 21. 22 cm. Burrow‐mottled silty limestone, chert stringers near top. 20. 53 cm. Mottled silty limestone, and up to 5 cm beds of rudite. 19. 7 cm. Burrowed limestone bed with discontinuous conglomeratic channels. 18. 82 cm. Thin to medium bedded burrow‐mottled silty limestone, occasionally laminated and with granule beds 1‐3 cm thick. 17. 22 cm. Burrow‐mottled silty limestone, angular chert clasts up to 3 cm at base forms bench. 16. 32 cm bedded, burrow‐mottled silty limestone. Beds up to 10 cm thick. 15. 185 cm. 2‐7cm thick bedded burrow‐mottled silty limestone. 14. 10 cm. Burrow‐mottled silty limestone. 13. 26 cm. Heavily burrowed (?Glossifungites) nodular silty limestone. 12. 5 cm. Matrix‐supported rudite interclasts that are angular, elongate, and up to 2 cm in length. 11. 13 cm. Nodular silty limestone, scattered burrows, a thinly bedded interval. 10. 7 cm. Nodular silty limestone, scattered burrows, scattered shells and vertical burrows. 9. 6 cm. Nodular silty limestone, scattered burrows. 8. 6 cm. Nodular silty limestone, scattered burrows. 7. 6 cm. Nodular silty limestone, scattered burrows. 95 6. 37 cm. Nodular silty limestone, scattered burrows. 5. 6 cm. Silty limestone, abundant fine lined burrows. Macluritid snails, 1‐2 cm in diameter. 4. 42.5 cm. Thickly‐bedded silty limestone, with closely packed fine (1‐2 mm diameter) lined burrows. 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