Publications by authors named "Simon Conway Morris"
By contrast to many previously enigmatic Palaeozoic fossils, the Carboniferous metazoan has defied phylogenetic placement. Here, we document new features, including possible phosphatized muscle tissues and a hitherto unrecognized feeding apparatus with two sets of 20 spinose teeth whose closest similarities appear to lie with the molluscan radula. The ribbon-like structure, located well behind the mouth area and deep into the anterior part of the body, is interpreted as being in an inverted proboscis configuration.
View Article and Find Full Text PDFCambrian annelids are strikingly diverse and reveal important details of annelid character acquisition. Their contribution, however, to a wider understanding of the evolution of the trochozoans (encompassing the annelids as well as such groups as the brachiopods and molluscs) remains limited. Thus the early annelids had been linked to a variety of cataphract Cambrian metazoans, notably Wiwaxia and the halkieriids, but recent work assigns such fossils to stem-group molluscs.
View Article and Find Full Text PDFThe notion that humans, in all their complexity, are merely an evolutionary accident, an insignificant speck in a boundless cosmos, is deeply unsatisfying for most nonscientists and fails to resonate with their life experience. What, then, can evolutionary biology ultimately tell us about the meaning of our lives? In conversation with Steve Paulson, executive producer and host of To the Best of Our Knowledge, paleoanthropologists Melanie Lee Chang and Ian Tattersall, and paleontologist Simon Conway Morris share their insights on these competing concepts and explain how meaning and purpose can be gleaned from the remarkable story of life itself.
View Article and Find Full Text PDFMacroscale rangeomorph fossils, with characteristic branching fronds, appear (571 Myr ago) after the Gaskiers glaciation (580 Myr ago). However, biological mechanisms of size growth and potential connections to ocean geochemistry were untested. Using micro-computerized tomography and photographic measurements, alongside mathematical and computer models, we demonstrate that growth of rangeomorph branch internodes declined as their relative surface area decreased.
View Article and Find Full Text PDFDeuterostomes include the group we belong to (vertebrates) as well as an array of disparate forms that include echinoderms, hemichordates and more problematic groups such as vetulicolians and vetulocystids. The Cambrian fossil record is well-populated with representative examples, but possible intermediates are controversial and the nature of the original deuterostome remains idealized. Here we report millimetric fossils, Saccorhytus coronarius nov.
View Article and Find Full Text PDFBackground: The combination of a meager fossil record of vermiform enteropneusts and their disparity with the tubicolous pterobranchs renders early hemichordate evolution conjectural. The middle Cambrian Oesia disjuncta from the Burgess Shale has been compared to annelids, tunicates and chaetognaths, but on the basis of abundant new material is now identified as a primitive hemichordate.
Results: Notable features include a facultative tubicolous habit, a posterior grasping structure and an extensive pharynx.
It all adds up …. Or does it? Numbers, mathematics and purpose.
Stud Hist Philos Biol Biomed Sci
August 2016
No chimpanzee knows what a square root is, let alone a complex number. Yet not only our closest ape cousins but even some invertebrates, possess a capacity for numerosity, that is the ability to assess relative numerical magnitudes and distances. That numerosity should confer adaptive advantages, such as social species that choose shoal size, is obvious.
View Article and Find Full Text PDFFractal branching organizations of Ediacaran rangeomorph fronds reveal a lost Proterozoic body plan.
Proc Natl Acad Sci U S A
September 2014
The branching morphology of Ediacaran rangeomorph fronds has no exact counterpart in other complex macroorganisms. As such, these fossils pose major questions as to growth patterns, functional morphology, modes of feeding, and adaptive optimality. Here, using parametric Lindenmayer systems, a formal model of rangeomorph morphologies reveals a fractal body plan characterized by self-similar, axial, apical, alternate branching.
View Article and Find Full Text PDFKnowledge of the early evolution of fish largely depends on soft-bodied material from the Lower (Series 2) Cambrian period of South China. Owing to the rarity of some of these forms and a general lack of comparative material from other deposits, interpretations of various features remain controversial, as do their wider relationships amongst post-Cambrian early un-skeletonized jawless vertebrates. Here we redescribe Metaspriggina on the basis of new material from the Burgess Shale and exceptionally preserved material collected near Marble Canyon, British Columbia, and three other Cambrian Burgess Shale-type deposits from Laurentia.
View Article and Find Full Text PDFHemichordates are a marine group that, apart from one monospecific pelagic larval form, are represented by the vermiform enteropneusts and minute colonial tube-dwelling pterobranchs. Together with echinoderms, they comprise the clade Ambulacraria. Despite their restricted diversity, hemichordates provide important insights into early deuterostome evolution, notably because of their pharyngeal gill slits.
View Article and Find Full Text PDFBackground: Vetulicolians are a group of Cambrian metazoans whose distinctive bodyplan continues to present a major phylogenetic challenge. Thus, we see vetulicolians assigned to groups as disparate as deuterostomes and ecdysozoans. This divergence of opinions revolves around a strikingly arthropod-like body, but one that also bears complex lateral structures on its anterior section interpreted as pharyngeal openings.
View Article and Find Full Text PDFPikaia gracilens Walcott, a stem-group chordate from the Middle Cambrian of British Columbia.
Biol Rev Camb Philos Soc
May 2012
The Middle Cambrian Pikaia gracilens (Walcott) has an iconic position as a Cambrian chordate, but until now no detailed description has been available. Here on the basis of the 114 available specimens we review its anatomy, confirm its place in the chordates and explore with varying degrees of confidence its relationships to both extant and extinct chordates and other deuterostomes. The body of Pikaia is fusiform, laterally compressed and possesses about 100 myomeres.
View Article and Find Full Text PDFBeing attacked by an octopus gives the opportunity to marvel at how convergent evolution created similar organs and senses in cephalopod and man.
View Article and Find Full Text PDFPredicting what extra-terrestrials will be like: and preparing for the worst.
Philos Trans A Math Phys Eng Sci
February 2011
It is difficult to imagine evolution in alien biospheres operating in any manner other than Darwinian. Yet, it is also widely assumed that alien life-forms will be just that: strange, un-nerving and probably repulsive. There are two reasons for this view.
View Article and Find Full Text PDFSimon Conway Morris marvels at the perfection of sensory organs: shaped by eons of evolution, they can detect a single photon or an individual molecule. Only scientific instruments are able to reach beyond the limits of nature's detectors.
View Article and Find Full Text PDFIf we ponder how alien life might look like on other planets, we don't have to go far, Simon Conway Morris argues, since life forms on Earth have already pushed life to the limits.
View Article and Find Full Text PDFMolecular and morphological evidence unite the hemichordates and echinoderms as the Ambulacraria, but their earliest history remains almost entirely conjectural. This is on account of the morphological disparity of the ambulacrarians and a paucity of obvious stem-groups. We describe here a new taxon Herpetogaster collinsi gen.
View Article and Find Full Text PDFEvolution: like any other science it is predictable.
Philos Trans R Soc Lond B Biol Sci
January 2010
Evolutionary biology rejoices in the diversity of life, but this comes at a cost: other than working in the common framework of neo-Darwinian evolution, specialists in, for example, diatoms and mammals have little to say to each other. Accordingly, their research tends to track the particularities and peculiarities of a given group and seldom enquires whether there are any wider or deeper sets of explanations. Here, I present evidence in support of the heterodox idea that evolution might look to a general theory that does more than serve as a tautology ('evolution explains evolution').
View Article and Find Full Text PDFThe predictability of evolution: glimpses into a post-Darwinian world.
Naturwissenschaften
November 2009
The very success of the Darwinian explanation, in not only demonstrating evolution from multiple lines of evidence but also in providing some plausible explanations, paradoxically seems to have served to have stifled explorations into other areas of investigation. The fact of evolution is now almost universally yoked to the assumption that its outcomes are random, trends are little more than drunkard's walks, and most evolutionary products are masterpieces of improvisation and far from perfect. But is this correct? Let us consider some alternatives.
View Article and Find Full Text PDFHalkieriids and wiwaxiids are cosmopolitan sclerite-bearing metazoans from the Lower and Middle Cambrian. Although they have similar scleritomes, their phylogenetic position is contested. A new scleritomous fossil from the Burgess Shale has the prominent anterior shell of the halkieriids but also bears wiwaxiid-like sclerites.
View Article and Find Full Text PDFDarwin's dilemma: the realities of the Cambrian 'explosion'.
Philos Trans R Soc Lond B Biol Sci
June 2006
The Cambrian 'explosion' is widely regarded as one of the fulcrum points in the history of life, yet its origins and causes remain deeply controversial. New data from the fossil record, especially of Burgess Shale-type Lagerstätten, indicate, however, that the assembly of bodyplans is not only largely a Cambrian phenomenon, but can already be documented in fair detail. This speaks against a much more ancient origin of the metazoans, and current work is doing much to reconcile the apparent discrepancies between the fossil record, including the Ediacaran assemblages of latest Neoproterozoic age and molecular 'clocks'.
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