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A new elpistostegalian from the Late Devonian of the Canadian Arctic. Nature 2022; 608:563-568. [PMID: 35859171 PMCID: PMC9385497 DOI: 10.1038/s41586-022-04990-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 06/17/2022] [Indexed: 12/03/2022]
Abstract
A fundamental gap in the study of the origin of limbed vertebrates lies in understanding the morphological and functional diversity of their closest relatives. Whereas analyses of the elpistostegalians Panderichthys rhombolepis, Tiktaalik roseae and Elpistostege watsoni have revealed a sequence of changes in locomotor, feeding and respiratory structures during the transition1–9, an isolated bone, a putative humerus, has controversially hinted at a wider range in form and function than now recognized10–14. Here we report the discovery of a new elpistostegalian from the Late Devonian period of the Canadian Arctic that shows surprising disparity in the group. The specimen includes partial upper and lower jaws, pharyngeal elements, a pectoral fin and scalation. This new genus is phylogenetically proximate to T. roseae and E. watsoni but evinces notable differences from both taxa and, indeed, other described tetrapodomorphs. Lacking processes, joint orientations and muscle scars indicative of appendage-based support on a hard substrate13, its pectoral fin shows specializations for swimming that are unlike those known from other sarcopterygians. This unexpected morphological and functional diversity represents a previously hidden ecological expansion, a secondary return to open water, near the origin of limbed vertebrates. A new elpistostegalian from the Late Devonian period has been discovered that shows disparity in the group and represents a previously hidden ecological expansion, a secondary return to open water, near the origin of limbed vertebrates.
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Cloutier R, Clement AM, Lee MSY, Noël R, Béchard I, Roy V, Long JA. Elpistostege and the origin of the vertebrate hand. Nature 2020; 579:549-554. [PMID: 32214248 DOI: 10.1038/s41586-020-2100-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 01/17/2020] [Indexed: 02/08/2023]
Abstract
The evolution of fishes to tetrapods (four-limbed vertebrates) was one of the most important transformations in vertebrate evolution. Hypotheses of tetrapod origins rely heavily on the anatomy of a few tetrapod-like fish fossils from the Middle and Late Devonian period (393-359 million years ago)1. These taxa-known as elpistostegalians-include Panderichthys2, Elpistostege3,4 and Tiktaalik1,5, none of which has yet revealed the complete skeletal anatomy of the pectoral fin. Here we report a 1.57-metre-long articulated specimen of Elpistostege watsoni from the Upper Devonian period of Canada, which represents-to our knowledge-the most complete elpistostegalian yet found. High-energy computed tomography reveals that the skeleton of the pectoral fin has four proximodistal rows of radials (two of which include branched carpals) as well as two distal rows that are organized as digits and putative digits. Despite this skeletal pattern (which represents the most tetrapod-like arrangement of bones found in a pectoral fin to date), the fin retains lepidotrichia (fin rays) distal to the radials. We suggest that the vertebrate hand arose primarily from a skeletal pattern buried within the fairly typical aquatic pectoral fin of elpistostegalians. Elpistostege is potentially the sister taxon of all other tetrapods, and its appendages further blur the line between fish and land vertebrates.
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Affiliation(s)
- Richard Cloutier
- Université du Québec à Rimouski, Rimouski, Quebec, Canada.
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia.
| | - Alice M Clement
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Michael S Y Lee
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
- Earth Sciences Section, South Australian Museum, Adelaide, South Australia, Australia
| | - Roxanne Noël
- Université du Québec à Rimouski, Rimouski, Quebec, Canada
| | | | - Vincent Roy
- Université du Québec à Rimouski, Rimouski, Quebec, Canada
| | - John A Long
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
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Marjanović D, Laurin M. Phylogeny of Paleozoic limbed vertebrates reassessed through revision and expansion of the largest published relevant data matrix. PeerJ 2019; 6:e5565. [PMID: 30631641 PMCID: PMC6322490 DOI: 10.7717/peerj.5565] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 08/12/2018] [Indexed: 01/23/2023] Open
Abstract
The largest published phylogenetic analysis of early limbed vertebrates (Ruta M, Coates MI. 2007. Journal of Systematic Palaeontology 5:69-122) recovered, for example, Seymouriamorpha, Diadectomorpha and (in some trees) Caudata as paraphyletic and found the "temnospondyl hypothesis" on the origin of Lissamphibia (TH) to be more parsimonious than the "lepospondyl hypothesis" (LH)-though only, as we show, by one step. We report 4,200 misscored cells, over half of them due to typographic and similar accidental errors. Further, some characters were duplicated; some had only one described state; for one, most taxa were scored after presumed relatives. Even potentially continuous characters were unordered, the effects of ontogeny were not sufficiently taken into account, and data published after 2001 were mostly excluded. After these issues are improved-we document and justify all changes to the matrix-but no characters are added, we find (Analysis R1) much longer trees with, for example, monophyletic Caudata, Diadectomorpha and (in some trees) Seymouriamorpha; Ichthyostega either crownward or rootward of Acanthostega; and Anthracosauria either crownward or rootward of Temnospondyli. The LH is nine steps shorter than the TH (R2; constrained) and 12 steps shorter than the "polyphyly hypothesis" (PH-R3; constrained). Brachydectes (Lysorophia) is not found next to Lissamphibia; instead, a large clade that includes the adelogyrinids, urocordylid "nectrideans" and aïstopods occupies that position. As expected from the taxon/character ratio, most bootstrap values are low. Adding 56 terminal taxa to the original 102 increases the resolution (and decreases most bootstrap values). The added taxa range in completeness from complete articulated skeletons to an incomplete lower jaw. Even though the lissamphibian-like temnospondyls Gerobatrachus, Micropholis and Tungussogyrinus and the extremely peramorphic salamander Chelotriton are added, the difference between LH (R4; unconstrained) and TH (R5) rises to 10 steps, that between LH and PH (R6) to 15; the TH also requires several more regains of lost bones than the LH. Casineria, in which we tentatively identify a postbranchial lamina, emerges rather far from amniote origins in a gephyrostegid-chroniosuchian grade. Bayesian inference (Analysis EB, settings as in R4) mostly agrees with R4. High posterior probabilities are found for Lissamphibia (1.00) and the LH (0.92); however, many branches remain weakly supported, and most are short, as expected from the small character sample. We discuss phylogeny, approaches to coding, methods of phylogenetics (Bayesian inference vs. equally weighted vs. reweighted parsimony), some character complexes (e.g. preaxial/postaxial polarity in limb development), and prospects for further improvement of this matrix. Even in its revised state, the matrix cannot provide a robust assessment of the phylogeny of early limbed vertebrates. Sufficient improvement will be laborious-but not difficult.
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Affiliation(s)
- David Marjanović
- Science Programme “Evolution and Geoprocesses”, Museum für Naturkunde—Leibniz Institute for Evolutionary and Biodiversity Research, Berlin, Germany
| | - Michel Laurin
- Centre de Recherches sur la Paléobiologie et les Paléoenvironnements (CR2P), Centre national de la Recherche scientifique (CNRS)/Muséum national d’Histoire naturelle (MNHN)/Sorbonne Université, Paris, France
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Molnar JL, Diogo R, Hutchinson JR, Pierce SE. Reconstructing pectoral appendicular muscle anatomy in fossil fish and tetrapods over the fins-to-limbs transition. Biol Rev Camb Philos Soc 2017; 93:1077-1107. [DOI: 10.1111/brv.12386] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Revised: 10/02/2017] [Accepted: 10/13/2017] [Indexed: 12/16/2022]
Affiliation(s)
- Julia L. Molnar
- Department of Anatomy; New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard; Old Westbury NY U.S.A
| | - Rui Diogo
- Department of Anatomy; Howard University College of Medicine, 520 W St. NW, Numa Adams Building; Washington DC 20059 U.S.A
| | - John R. Hutchinson
- Structure and Motion Lab; Royal Veterinary College, Hawkshead Lane, Hatfield; Hertfordshire AL9 7TA UK
| | - Stephanie E. Pierce
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology; Harvard University, 26 Oxford Street; Cambridge MA 02138 U.S.A
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Miyake T, Kumamoto M, Iwata M, Sato R, Okabe M, Koie H, Kumai N, Fujii K, Matsuzaki K, Nakamura C, Yamauchi S, Yoshida K, Yoshimura K, Komoda A, Uyeno T, Abe Y. The pectoral fin muscles of the coelacanthLatimeria chalumnae: Functional and evolutionary implications for the fin-to-limb transition and subsequent evolution of tetrapods. Anat Rec (Hoboken) 2016; 299:1203-23. [DOI: 10.1002/ar.23392] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 05/25/2016] [Indexed: 12/27/2022]
Affiliation(s)
- Tsutomu Miyake
- The Graduate School of Science and Technology; Keio University; Tokyo Japan
- Department of Anatomy; The Jikei University School of Medicine; Tokyo Japan
| | | | | | - Ryuichi Sato
- Institute of Biomechanical Control Systems; Kanazawa Institute of Technology; Hakusan Japan
| | - Masataka Okabe
- Department of Anatomy; The Jikei University School of Medicine; Tokyo Japan
| | - Hiroshi Koie
- Department of Veterinary Medicine; Nihon University; Fujisawa Japan
| | - Nori Kumai
- Research Center of Computational Mechanics (RCCM), Inc; Tokyo Japan
| | - Kenichi Fujii
- Aquamarine Fukushima; Marine Science Museum; Iwaki Japan
| | - Koji Matsuzaki
- Aquamarine Fukushima; Marine Science Museum; Iwaki Japan
| | - Chiho Nakamura
- Aquamarine Fukushima; Marine Science Museum; Iwaki Japan
| | | | - Kosuke Yoshida
- Aquamarine Fukushima; Marine Science Museum; Iwaki Japan
| | | | - Akira Komoda
- Aquamarine Fukushima; Marine Science Museum; Iwaki Japan
| | - Teruya Uyeno
- National Museum of Nature and Science; Tokyo Japan
| | - Yoshitaka Abe
- Aquamarine Fukushima; Marine Science Museum; Iwaki Japan
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Dececchi TA, Mabee PM, Blackburn DC. Data Sources for Trait Databases: Comparing the Phenomic Content of Monographs and Evolutionary Matrices. PLoS One 2016; 11:e0155680. [PMID: 27191170 PMCID: PMC4871461 DOI: 10.1371/journal.pone.0155680] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 05/03/2016] [Indexed: 01/17/2023] Open
Abstract
Databases of organismal traits that aggregate information from one or multiple sources can be leveraged for large-scale analyses in biology. Yet the differences among these data streams and how well they capture trait diversity have never been explored. We present the first analysis of the differences between phenotypes captured in free text of descriptive publications ('monographs') and those used in phylogenetic analyses ('matrices'). We focus our analysis on osteological phenotypes of the limbs of four extinct vertebrate taxa critical to our understanding of the fin-to-limb transition. We find that there is low overlap between the anatomical entities used in these two sources of phenotype data, indicating that phenotypes represented in matrices are not simply a subset of those found in monographic descriptions. Perhaps as expected, compared to characters found in matrices, phenotypes in monographs tend to emphasize descriptive and positional morphology, be somewhat more complex, and relate to fewer additional taxa. While based on a small set of focal taxa, these qualitative and quantitative data suggest that either source of phenotypes alone will result in incomplete knowledge of variation for a given taxon. As a broader community develops to use and expand databases characterizing organismal trait diversity, it is important to recognize the limitations of the data sources and develop strategies to more fully characterize variation both within species and across the tree of life.
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Affiliation(s)
- T. Alex Dececchi
- Department of Biology, University of South Dakota, Vermillion, South Dakota, United States of America
| | - Paula M. Mabee
- Department of Biology, University of South Dakota, Vermillion, South Dakota, United States of America
| | - David C. Blackburn
- Florida Museum of Natural History, University of Florida, Gainesville, Florida, United States of America
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Hilton EJ, Schnell NK, Konstantinidis P. When Tradition Meets Technology: Systematic Morphology of Fishes in the Early 21stCentury. COPEIA 2015. [DOI: 10.1643/ci-14-178] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
The lack of fossil tetrapod bearing deposits in the earliest Carboniferous (‘Romer’s Gap’) has provoked some recent discussions regarding the proximal cause, with three explanations being offered: environmental, taphonomic, and collection failure. One of the few, and earliest, windows into this time is the locality of Blue Beach exposed in the Tournaisian deposits at Horton Bluff lying along the Avon River near Hantsport, Nova Scotia, Canada. This locality has long been known but, because the fossils were deposited in high energy settings they are almost always disarticulated, so the fauna has not been described in detail. Recent intensive collection has revealed a diverse assemblage of material, including for the first time associated elements, which permits an evaluation of the faunal constituents at the locality. Although not diagnosable to a fine taxonomic level, sufficient apomorphies are present to identify representatives from numerous clades known from more complete specimens elsewhere. The evidence suggests a diverse fauna was present, including whatcheeriids and embolomeres. A single humerus previously had been attributed to a colosteid, but there is some uncertainty with this identification. Additional elements suggest the presence of taxa otherwise only known from the late Devonian. Depositional biases at the locality favor tetrapod fossils from larger individuals, but indirect evidence from trackways and tantalizing isolated bones evidences the presence of small taxa that remain to be discovered. The fossils from Blue Beach demonstrate that when windows into the fauna of ‘Romer’s Gap’ are found a rich diversity of tetrapods will be shown to be present, contra arguments that suggested this hiatus in the fossil record was due to extrinsic factors such as atmospheric oxygen levels. They also show that the early tetrapod fauna is not easily divisible into Devonian and Carboniferous faunas, suggesting that some tetrapods passed through the end Devonian extinction event unaffected.
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Holland T. Pectoral girdle and fin anatomy ofGogonasus andrewsaelong, 1985: Implications for tetrapodomorph limb evolution. J Morphol 2012; 274:147-64. [DOI: 10.1002/jmor.20078] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 06/25/2012] [Accepted: 07/10/2012] [Indexed: 11/06/2022]
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Meunier FJ, Laurin M. A microanatomical and histological study of the fin long bones of the Devonian sarcopterygian Eusthenopteron foordi. ACTA ZOOL-STOCKHOLM 2010. [DOI: 10.1111/j.1463-6395.2010.00489.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Conway Morris S. The predictability of evolution: glimpses into a post-Darwinian world. Naturwissenschaften 2009; 96:1313-37. [PMID: 19784612 DOI: 10.1007/s00114-009-0607-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 08/17/2009] [Accepted: 08/27/2009] [Indexed: 01/01/2023]
Abstract
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. Is there evidence that evolution could in anyway be predictable? Can we identify alternative forms of biological organizations and if so how viable are they? Why are some molecules so extraordinarily versatile, while others can be spoken of as "molecules of choice"? How fortuitous are the major transitions in the history of life? What implications might this have for the Tree of Life? To what extent is evolutionary diversification constrained or facilitated by prior states? Are evolutionary outcomes merely sufficient or alternatively are they highly efficient, even superb? Here I argue that in sharp contradistinction to an orthodox Darwinian view, not only is evolution much more predictable than generally assumed but also investigation of its organizational substrates, including those of sensory systems, which indicates that it is possible to identify a predictability to the process and outcomes of evolution. If correct, the implications may be of some significance, not least in separating the unexceptional Darwinian mechanisms from underlying organizational principles, which may indicate evolutionary inevitabilities.
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Affiliation(s)
- Simon Conway Morris
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, UK.
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