DOCSLIB.ORG

A Devonian Tetrapod-Like Fish Reveals Substantial Parallelism in Stem Tetrapod Evolution

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
A Devonian Tetrapod-Like Fish Reveals Substantial Parallelism in Stem Tetrapod Evolution ARTICLES DOI: 10.1038/s41559-017-0293-5 A Devonian tetrapod-like fish reveals substantial parallelism in stem tetrapod evolution Min Zhu 1,2*, Per E. Ahlberg 3*, Wen-Jin Zhao1,2 and Lian-Tao Jia1 The fossils assigned to the tetrapod stem group document the evolution of terrestrial vertebrates from lobe-finned fishes. During the past 18 years the phylogenetic structure of this stem group has remained remarkably stable, even when accommo- dating new discoveries such as the earliest known stem tetrapod Tungsenia and the elpistostegid (fish–tetrapod intermediate) Tiktaalik. Here we present a large lobe-finned fish from the Late Devonian period of China that disrupts this stability. It com- bines characteristics of rhizodont fishes (supposedly a basal branch in the stem group, distant from tetrapods) with derived elpistostegid-like and tetrapod-like characters. This mélange of characters may reflect either detailed convergence between rhizodonts and elpistostegids plus tetrapods, under a phylogenetic scenario deduced from Bayesian inference analysis, or a previously unrecognized close relationship between these groups, as supported by maximum parsimony analysis. In either case, the overall result reveals a substantial increase in homoplasy in the tetrapod stem group. It also suggests that ecological diversity and biogeographical provinciality in the tetrapod stem group have been underestimated. he colonization of the land by animals during the mid-Palaeozoic in 2002 and described here, provides a first and highly sur- involved the evolution of complex suites of adaptations. prising glimpse of sarcopterygian diversity in the Devonian of The incidence and importance of evolutionary convergence North China (Figs. 1–4 and Supplementary Figs. 1–3). It com- T 17–26 in this process appears to have varied greatly between groups. bines characteristics of rhizodont fishes (supposedly a basal Several arthropod clades independently achieved terrestrial- branch in the stem group) with derived elpistostegid-like and ity during the Silurian period or earlier1. By contrast, tetrapods tetrapod-like characters, including a remarkably tetrapod- (defined here as vertebrates with limbs and digits)2 are mono- like shoulder girdle10,27, hinting at an unanticipated ecological phyletic, and their sister group relationship to the elpistostegids diversity and challenging the accepted consensus view of the Panderichthys, Elpistostege and Tiktaalik is robustly supported2–10, fish–tetrapod transition. suggesting that vertebrates underwent just a single transition from water to land. The lobe-finned fishes that form the lower part of Results the tetrapod stem group, below the elpistostegids, do not show Systematic palaeontology. Osteichthyes Huxley, 1880 convergent acquisition of terrestrial adaptations; although, there Sarcopterygii Romer, 1955 are repeated trends towards large body size and an elpistostegid- Tetrapodomorpha Ahlberg, 1991 like morphology2. The phylogenetic topology of the tetrapod stem Hongyu chowi gen. et sp. nov. group has remained essentially stable through repeated analyses Etymology. The generic name derives from hong (Chinese Pinyin), over the last 18 years2–9. which means large and yu (Chinese Pinyin), which means fish. The The North China Block, an ancient craton complex, was a small specific is in honor of Min-Chen Chow. continent located near the Equator during the Devonian period11–13. Holotype. IVPP V17681, a three-dimensionally preserved and par- The distribution of regionally endemic groups of Devonian verte- tially articulated specimen. brates, such as galeaspids and sinolepid antiarchs, indicates close Locality. A quarry at Shixiagou, Qingtongxia, Ningxia, China. proximity or even contact at this time between the North China Approximate coordinates: 37° 39′ 18.4″ N, 105° 59′ 34.2″ E. Block, the South China Block and eastern Gondwana12–14. Silurian Horizon. Zhongning Formation, Famennian, Late Devonian deposits within the South China Block contain the earliest fossils of period. sarcopterygian (lobe-finned) fishes in the world, suggesting that the Diagnosis. Large fin-bearing tetrapodomorph with the following clade Sarcopterygii may have originated there15; early sarcopteryg- unique character combination: a jagged margin along the dermal ian fossils from neighbouring North China are therefore potentially intracranial joint, posterior margin of tabular anterior to that of the of great evolutionary and biogeographical interest. However, until postparietal, an extremely flat lower jaw with a large rectangular ret- now, the only Devonian sarcopterygian from the North China Block roarticular process, single large lateral line pore at extratemporal– that has been described, is the tetrapod Sinostega, represented by a supratemporal junction, hyomandibula with an opercular process at single incomplete lower jaw from the Famennian (latest Devonian) the distal end, a large plate-like scapulocoracoid without foramina, Zhongning Formation of the Ningxia Hui Autonomous Region16. cleithrum without ventral lamina, distinct atlas vertebra articulating The partly articulated skeleton of a large lobe-finned fish with occiput, vertebrae with ring centra, round thin scales without from the Zhongning Formation, discovered by P.E.A. and M.Z. an internal median boss. 1 Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, PO Box 643, Beijing 100044, China. 2 College of Earth Science, University of Chinese Academy of Sciences, Beijing 100049, China. 3 Subdepartment of Evolution and Development, Department of Organismal Biology, Evolutionary Biology Centre, Uppsala University, Uppsala 752 36, Sweden. *e-mail: [email protected]; [email protected] 1470 NatURE ECOLOGY & EVOLUTION | VOL 1 | OCTOBER 2017 | 1470–1476 | www.nature.com/natecolevol © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. NATURE ECOLOGY & EVOLUTION ARTICLES ab c d Surangular Prearticular Entopterygoid It Pa hy Unidentified bones Gular plate Angular Dentary Dentary po Cleithrum Pq Pp St sc n.arch Ta sc Cleithrum Clavicle hy Et retro phbr retro cla.sp oa.sc chy scap pit cla.sp Glenoid cla.sp sc sq buttress ebr 1–2 at.v ebr 1–2 gle rad scap cbr 4–5 rad gle cbr 1–5 sc sc Scapular Anamestic Premaxillary process scap bone Glenoid buttress gle ac.gle sc Lepidotrichia Canal for Neural spine notochord 15th Attachment for haemal arch 15th vertebra Unidentified dermal bone vertebra Attachment for neural arch Rib attachment 10 cm 22nd vertebra 22nd vertebra Fig. 1 | V17681, holotype of Hongyu chowi gen. et sp. nov. a, Dorsal view (photo). b, Ventral view (photo). c, Dorsal view (drawing). d, Ventral view (drawing). ac.gle, anterior cam of glenoid facet; at.v, atlas vertebra; cbr, ceratobranchial; chy, ceratohyal; cla.sp, clavicular spine; ebr, epibranchial; Et, extratemporal; gle, glenoid facet; hy, hyomandibula; It, intertemporal; n.arch, neural arch; oa.sc, area overlapped by scale; Pa, parietal; phbr, pharyngobranchial; po, lateral line pore; Pp, postparietal; Pq, palatoquadrate; rad, radial; retro, retroarticular process; sc, scale; scap, scapulocoracoid; sq, squamosal; St, supratemporal; Ta, tabular. Taxonomic note. We use the name Tetrapodomorpha for the tet- displaced by flowing water: the left premaxilla, left squamosal and rapod total group28 and restrict Tetrapoda to the limbed vertebrates a third unidentified dermal bone are scattered to the right of the (limbed stem tetrapods plus the tetrapod crown group)4,10. Hongyu, vertebral column. Opercular and extrascapular bones are absent. like Tiktaalik, belongs to the finned stem tetrapods and is therefore The strongly ossified gill skeleton is well preserved, as is the partly a member of the Tetrapodomorpha, but not the Tetrapoda. disarticulated pectoral girdle. The vertebral column consists of ring centra with loosely attached, slender neural arches. A patch of lepi- Discussion dotrichia with long basal segments, and a couple of slender radial Mélange of characters. The specimen comprises the posterior part elements, represent the right pectoral fin. of the skull, the gill skeleton and pectoral girdle, and the anterior In many respects Hongyu resembles a rhizodont, a widely dis- vertebral column of a large fish (Fig. 1a,b). It is slightly compressed tributed group of large to very large predatory tetrapodomorph dorsoventrally but essentially three-dimensional. Unfortunately, fishes known from the Devonian and Carboniferous periods17–26. the snout region was not recovered (the specimen was found in Supratemporal–extratemporal contact is a derived rhizodont char- the working face of an active quarry and this part seems to have acter (albeit shared with onychodonts), as is the tall facial lamina of been lost to the quarrying process), but the posterior end of the the premaxilla19,22. A large robust shoulder girdle with a tall clavicu- ethmosphenoid is preserved along with the posterior half of the lar spine, thin round scales, and a proportionately broad head are left palatoquadrate, which is still in articulation with the lower jaw. also typical rhizodont features18,19,22–24. The shape of the squamosal, The dermal bones of the cheeks and snout appear to have been which resembles that of the rhizodont Screbinodus17,18, suggests that NatURE ECOLOGY & EVOLUTION | VOL 1 | OCTOBER 2017 | 1470–1476 | www.nature.com/natecolevol
Load more

Recommended publications
  • Ontogenetic Evidence for the Paleozoic Ancestry of Salamanders
    EVOLUTION & DEVELOPMENT 5:3, 314–324 (2003) Ontogenetic evidence for the Paleozoic ancestry of salamanders Rainer R. Schocha and Robert L. Carrollb aStaatlilches Museum für Naturkunde, Rosenstein 1, D-70191 Stuttgart, Germany bRedpath Museum, McGill University, Montréal, Québec, Canada, H3A 2K6 Authors for correspondence (e-mail: [email protected], [email protected]) SUMMARY The phylogenetic positions of frogs, sala- tire developmental sequence from hatching to metamor- manders, and caecilians have been difficult to establish. phosis is revealed in an assemblage of over 600 Data matrices based primarily on Paleozoic taxa support a specimens from a single locality, all belonging to the genus monophyletic origin of all Lissamphibia but have resulted in Apateon. Apateon forms the most speciose genus of the widely divergent hypotheses of the nature of their common neotenic temnospondyl family Branchiosauridae. The se- ancestor. Analysis that concentrates on the character quence of ossification of individual bones and the changing states of the stem taxa of the extant orders, in contrast, configuration of the skull closely parallel those observed in suggests a polyphyletic origin from divergent Paleozoic the development of primitive living salamanders. These clades. Comparison of patterns of larval development in fossils provide a model of how derived features of the sala- Paleozoic and modern amphibians provides a means to mander skull may have evolved in the context of feeding test previous phylogenies based primarily on adult charac- specializations that appeared in early larval stages of mem- teristics. This proves to be highly informative in the case of bers of the Branchiosauridae. Larvae of Apateon share the origin of salamanders.
    [Show full text]
  • A New Osteolepidid Fish From
    Rea. West. Aust. MU8. 1985, 12(3): 361-377 ANew Osteolepidid Fish from the Upper Devonian Gogo Formation, Western Australia J.A. Long* Abstract A new osteolepidid crossopterygian, Gogonasus andrewsi gen. et sp. nov., is des­ cribed from a single fronto-ethmoidal shield and associated ethmosphenoid, from the Late Devonian (Frasnian) Gogo Formation, Western Australia. Gogonasus is is distinguished from other osteolepids by the shape and proportions of the fronto­ ethmoidal shield, absence of palatal fenestrae, well developed basipterygoid pro­ cesses and moderately broad parasphenoid. The family Osteolepididae is found to be paraphyletic, with Gogonasus being regarded as a plesiomorphic osteolepidid at a similar level of organisation to Thursius. Introduction Much has been published on the well-preserved Late Devonian fish fauna from the Gogo Formation, Western Australia, although to date all the papers describing fish have been on placoderms (Miles 1971; Miles and Dennis 1979; Dennis and Miles 1979-1983; Young 1984), palaeoniscoids (Gardiner 1973, 1984; Gardiner and Bartram 1977) or dipnoans (Miles 1977; Campbell and Barwick 1982a, 1982b, 1983, 1984a). This paper describes the only osteolepiform from the fauna (Gardiner and Miles 1975), a small snout with associated braincase, ANU 21885, housed in the Geology Department, Australian National University. The specimen, collected by the Australian National University on the 1967 Gogo Expedition, was prepared by Dr S.M. Andrews (Royal Scottish Museum) and later returned to the ANU. Onychodus is the only other crossopterygian in the fauna. In its proportions and palatal structure the new specimen provides some additional new points of the anatomy of osteolepiforms. Few Devonian crossopte­ rygians are known from Australia, and so the specimen is significant in having resemblances to typical Northern Hemisphere species.
    [Show full text]
  • Spiracular Air Breathing in Polypterid Fishes and Its Implications for Aerial
    ARTICLE Received 1 May 2013 | Accepted 27 Nov 2013 | Published 23 Jan 2014 DOI: 10.1038/ncomms4022 Spiracular air breathing in polypterid fishes and its implications for aerial respiration in stem tetrapods Jeffrey B. Graham1, Nicholas C. Wegner1,2, Lauren A. Miller1, Corey J. Jew1, N Chin Lai1,3, Rachel M. Berquist4, Lawrence R. Frank4 & John A. Long5,6 The polypterids (bichirs and ropefish) are extant basal actinopterygian (ray-finned) fishes that breathe air and share similarities with extant lobe-finned sarcopterygians (lungfishes and tetrapods) in lung structure. They are also similar to some fossil sarcopterygians, including stem tetrapods, in having large paired openings (spiracles) on top of their head. The role of spiracles in polypterid respiration has been unclear, with early reports suggesting that polypterids could inhale air through the spiracles, while later reports have largely dismissed such observations. Here we resolve the 100-year-old mystery by presenting structural, behavioural, video, kinematic and pressure data that show spiracle-mediated aspiration accounts for up to 93% of all air breaths in four species of Polypterus. Similarity in the size and position of polypterid spiracles with those of some stem tetrapods suggests that spiracular air breathing may have been an important respiratory strategy during the fish-tetrapod transition from water to land. 1 Marine Biology Research Division, Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, USA. 2 Fisheries Resource Division, Southwest Fisheries Science Center, NOAA Fisheries, La Jolla, California 92037, USA. 3 VA San Diego Healthcare System, San Diego, California 92161, USA.
    [Show full text]
  • The Devonian Tetrapod Acanthostega Gunnari Jarvik: Postcranial Anatomy, Basal Tetrapod Interrelationships and Patterns of Skeletal Evolution M
    Transactions of the Royal Society of Edinburgh: Earth Sciences, 87, 363-421, 1996 The Devonian tetrapod Acanthostega gunnari Jarvik: postcranial anatomy, basal tetrapod interrelationships and patterns of skeletal evolution M. I. Coates ABSTRACT: The postcranial skeleton of Acanthostega gunnari from the Famennian of East Greenland displays a unique, transitional, mixture of features conventionally associated with fish- and tetrapod-like morphologies. The rhachitomous vertebral column has a primitive, barely differentiated atlas-axis complex, encloses an unconstricted notochordal canal, and the weakly ossified neural arches have poorly developed zygapophyses. More derived axial skeletal features include caudal vertebral proliferation and, transiently, neural radials supporting unbranched and unsegmented lepidotrichia. Sacral and post-sacral ribs reiterate uncinate cervical and anterior thoracic rib morphologies: a simple distal flange supplies a broad surface for iliac attachment. The octodactylous forelimb and hindlimb each articulate with an unsutured, foraminate endoskeletal girdle. A broad-bladed femoral shaft with extreme anterior torsion and associated flattened epipodials indicates a paddle-like hindlimb function. Phylogenetic analysis places Acanthostega as the sister- group of Ichthyostega plus all more advanced tetrapods. Tulerpeton appears to be a basal stem- amniote plesion, tying the amphibian-amniote split to the uppermost Devonian. Caerorhachis may represent a more derived stem-amniote plesion. Postcranial evolutionary trends spanning the taxa traditionally associated with the fish-tetrapod transition are discussed in detail. Comparison between axial skeletons of primitive tetrapods suggests that plesiomorphic fish-like morphologies were re-patterned in a cranio-caudal direction with the emergence of tetrapod vertebral regionalisation. The evolution of digited limbs lags behind the initial enlargement of endoskeletal girdles, whereas digit evolution precedes the elaboration of complex carpal and tarsal articulations.
    [Show full text]
  • Reconstructing Pectoral Appendicular Muscle Anatomy in Fossil Fish and Tetrapods Over the Fins-To-Limbs Transition
    Biol. Rev. (2017), pp. 000–000. 1 doi: 10.1111/brv.12386 Reconstructing pectoral appendicular muscle anatomy in fossil fish and tetrapods over the fins-to-limbs transition Julia L. Molnar1,∗ , Rui Diogo2, John R. Hutchinson3 and Stephanie E. Pierce4 1Department of Anatomy, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, Old Westbury, NY, U.S.A. 2Department of Anatomy, Howard University College of Medicine, 520 W St. NW, Numa Adams Building, Washington, DC 20059, U.S.A. 3Structure and Motion Lab, Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire AL9 7TA, UK 4Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, U.S.A. ABSTRACT The question of how tetrapod limbs evolved from fins is one of the great puzzles of evolutionary biology. While palaeontologists, developmental biologists, and geneticists have made great strides in explaining the origin and early evolution of limb skeletal structures, that of the muscles remains largely unknown. The main reason is the lack of consensus about appendicular muscle homology between the closest living relatives of early tetrapods: lobe-finned fish and crown tetrapods. In the light of a recent study of these homologies, we re-examined osteological correlates of muscle attachment in the pectoral girdle, humerus, radius, and ulna of early tetrapods and their close relatives. Twenty-nine extinct and six extant sarcopterygians were included in a meta-analysis using information from the literature and from original specimens, when possible. We analysed these osteological correlates using parsimony-based character optimization in order to reconstruct muscle anatomy in ancestral lobe-finned fish, tetrapodomorph fish, stem tetrapods, and crown tetrapods.
    [Show full text]
  • I Ecomorphological Change in Lobe-Finned Fishes (Sarcopterygii
    Ecomorphological change in lobe-finned fishes (Sarcopterygii): disparity and rates by Bryan H. Juarez A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science (Ecology and Evolutionary Biology) in the University of Michigan 2015 Master’s Thesis Committee: Assistant Professor Lauren C. Sallan, University of Pennsylvania, Co-Chair Assistant Professor Daniel L. Rabosky, Co-Chair Associate Research Scientist Miriam L. Zelditch i © Bryan H. Juarez 2015 ii ACKNOWLEDGEMENTS I would like to thank the Rabosky Lab, David W. Bapst, Graeme T. Lloyd and Zerina Johanson for helpful discussions on methodology, Lauren C. Sallan, Miriam L. Zelditch and Daniel L. Rabosky for their dedicated guidance on this study and the London Natural History Museum for courteously providing me with access to specimens. iii TABLE OF CONTENTS ACKNOWLEDGEMENTS ii LIST OF FIGURES iv LIST OF APPENDICES v ABSTRACT vi SECTION I. Introduction 1 II. Methods 4 III. Results 9 IV. Discussion 16 V. Conclusion 20 VI. Future Directions 21 APPENDICES 23 REFERENCES 62 iv LIST OF TABLES AND FIGURES TABLE/FIGURE II. Cranial PC-reduced data 6 II. Post-cranial PC-reduced data 6 III. PC1 and PC2 Cranial and Post-cranial Morphospaces 11-12 III. Cranial Disparity Through Time 13 III. Post-cranial Disparity Through Time 14 III. Cranial/Post-cranial Disparity Through Time 15 v LIST OF APPENDICES APPENDIX A. Aquatic and Semi-aquatic Lobe-fins 24 B. Species Used In Analysis 34 C. Cranial and Post-Cranial Landmarks 37 D. PC3 and PC4 Cranial and Post-cranial Morphospaces 38 E. PC1 PC2 Cranial Morphospaces 39 1-2.
    [Show full text]
  • A Second Species of Tristichopterus (Sarcopterygii: Tristichopteridae), from the Upper Devonian of the Baltic Region
    Memoirs of the Queensland Museum | Nature 56 (2) © Queensland Museum 2013 PO Box 3300, South Brisbane 4101, Australia Phone 06 7 3840 7555 Fax 06 7 3846 1226 Email [email protected] Website www.qm.qld.gov.au National Library of Australia card number ISSN 0079-8835 NOTE Papers published in this volume and in all previous volumes of the Memoirs of the Queensland Museum may be reproduced for scientific research, individual study or other educational purposes. Properly acknowledged quotations may be made but queries regarding the republication of any papers should be addressed to the Director. Copies of the journal can be purchased from the Queensland Museum Shop. A Guide to Authors is displayed at the Queensland Museum web site www.qm.qld.gov.au A Queensland Government Project Typeset at the Queensland Museum A second species of Tristichopterus (Sarcopterygii: Tristichopteridae), from the Upper Devonian of the Baltic Region Peter J. BISHOP Queensland Museum, Ancient Environments Program, 122 Gerler Rd, Hendra, Qld 4011 Citation: Bishop, P.J. 2012 06 30. A second species of Tristichopterus (Sarcopterygii: Tristichopteridae), from the Upper Devonian of the Baltic Region. Memoirs of the Queensland Museum – Nature 56(2): 305–309. Brisbane. ISSN 0079–8835. Accepted: 14 November 2012. ABSTRACT A review of the osteology of the tristichopterid sarcopterygian Eusthenopteron kurshi Zupiņš, 2008, from the Lower Frasnian of Latvia, indicates that it should be placed in the genus Tristichopterus, and a new combination Tristichopterus kurshi Zupiņš is proposed. The features that support this include: the number of coronoid fangs, proportions of the coronoids and the skull roof, and the relatively small epichordal lobe of the caudal fin.
    [Show full text]
  • Tiktaalik—A Fishy 'Missing Link'
    Countering the Critics Tiktaalik—a fishy ‘missing link’ Jonathan Sarfati he secularized mainstream media (MSM) are gleefully Is it transitional? promoting a recent find, Tiktaalik roseae (figure 1), as T Clack and others are naturally enthusiastic about Tikta- the end of any creationist or intelligent design idea. Some paleontologists are claiming that this is ‘a link between fishes alik’s transitional status. But this is not surprising—to her, and land vertebrates that might in time become as much of an we are all fishes anyway! She states: evolutionary icon as the proto-bird Archaeopteryx.’1 ‘Although humans do not usually think of So is Tiktaalik real evidence that fish evolved into tetra- themselves as fishes, they nonetheless share several pods (four-limbed vertebrates, i.e. amphibians, reptiles, mam- fundamental characters that unite them inextricably mals and birds)? As will be shown, there are parallels with with their relatives among the fishes … Tetrapods Archaeopteryx, the famous alleged reptile-bird intermediate, did not evolve from sarcopterygians [lobe-finned but not in the way the above quote claims! fishes]; theyare sarcopterygians, just as one would The alleged fish-to-tetrapod evolutionary transition is full of difficulties.2 In this, it parallels the record of dinosaur-to-bird,3 mammal-like reptiles,4 land-mam- mal-to-whale5 and ape-to-human evolution;6 superficially plausible, but when analyzed in depth, it col- lapses, for many parallel reasons. What was found? The above quote comes from two leading European experts in the alleged evolutionary transition from fish to tetrapod, Per Ahlberg and Jennifer Clack.
    [Show full text]
  • Fins to Limbs: What the Fossils Say1
    EVOLUTION & DEVELOPMENT 4:5, 390–401 (2002) Fins to limbs: what the fossils say1 Michael I. Coates,a,* Jonathan E. Jeffery,b and Marcello Rutaa aDepartment of Organismal Biology and Anatomy, University of Chicago, 1027 E57th Street, Chicago, IL 60637, USA bInstitute of Evolutionary and Ecological Sciences, Leiden University, Kaiserstraat 63, Postbus 9516, 2300 RA Leiden, The Netherlands *Author for correspondence (email: [email protected]) 1From the symposium on Starting from Fins: Parallelism in the Evolution of Limbs and Genitalia. SUMMARY A broad phylogenetic review of fins, limbs, and highlight a large data gap in the stem group preceding the first girdles throughout the stem and base of the crown group is appearance of limbs with digits. It is also noted that the record needed to get a comprehensive idea of transformations unique of morphological diversity among stem tetrapods is somewhat to the assembly of the tetrapod limb ground plan. In the lower worse than that of basal crown group tetrapods. The pre-limbed part of the tetrapod stem, character state changes at the pecto- evolution of stem tetrapod paired fins is marked by a gradual re- ral level dominate; comparable pelvic level data are limited. In duction in axial segment numbers (mesomeres); pectoral fins of more crownward taxa, pelvic level changes dominate and re- the sister group to limbed tetrapods include only three. This re- peatedly precede similar changes at pectoral level. Concerted duction in segment number is accompanied by increased re- change at both levels appears to be the exception rather than gional specialization, and these changes are discussed with the rule.
    [Show full text]
  • Tinkering and the Origins of Heritable Anatomical Variation in Vertebrates
    biology Review Tinkering and the Origins of Heritable Anatomical Variation in Vertebrates Jonathan B. L. Bard Department of Anatomy, Physiology & Genetics, University of Oxford, Oxford OX313QX, UK; [email protected] Received: 9 October 2017; Accepted: 18 February 2018; Published: 26 February 2018 Abstract: Evolutionary change comes from natural and other forms of selection acting on existing anatomical and physiological variants. While much is known about selection, little is known about the details of how genetic mutation leads to the range of heritable anatomical variants that are present within any population. This paper takes a systems-based view to explore how genomic mutation in vertebrate genomes works its way upwards, though changes to proteins, protein networks, and cell phenotypes to produce variants in anatomical detail. The evidence used in this approach mainly derives from analysing anatomical change in adult vertebrates and the protein networks that drive tissue formation in embryos. The former indicate which processes drive variation—these are mainly patterning, timing, and growth—and the latter their molecular basis. The paper then examines the effects of mutation and genetic drift on these processes, the nature of the resulting heritable phenotypic variation within a population, and the experimental evidence on the speed with which new variants can appear under selection. The discussion considers whether this speed is adequate to explain the observed rate of evolutionary change or whether other non-canonical, adaptive mechanisms of heritable mutation are needed. The evidence to hand suggests that they are not, for vertebrate evolution at least. Keywords: anatomical change; evolutionary change; developmental process; embryogenesis; growth; mutation; patterning in embryos; protein network; systems biology; variation 1.
    [Show full text]
  • Sarcopterygii, Tetrapodomorpha
    Tristichopterids (Sarcopterygii, Tetrapodomorpha) from the Upper Devonian tetrapod-bearing locality of Strud (Belgium, upper Famennian), with phylogenetic and paleobiogeographic considerations Sébastien Olive, Yann Leroy, Edward Daeschler, Jason Downs, S. Ladevèze, Gaël Clément To cite this version: Sébastien Olive, Yann Leroy, Edward Daeschler, Jason Downs, S. Ladevèze, et al.. Tristi- chopterids (Sarcopterygii, Tetrapodomorpha) from the Upper Devonian tetrapod-bearing locality of Strud (Belgium, upper Famennian), with phylogenetic and paleobiogeographic considerations. Journal of Vertebrate Paleontology, Society of Vertebrate Paleontology, 2020, 40 (1), pp.e1768105. 10.1080/02724634.2020.1768105. hal-03099746 HAL Id: hal-03099746 https://hal.archives-ouvertes.fr/hal-03099746 Submitted on 6 Jan 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Journal of Vertebrate Paleontology: For Review Only Tristichopterids (Sarcopterygii, Tetrapodomorpha) from the Late Devonian tetrapod-bearing locality of Strud (Belgium, late Famennian), with phylogenetic
    [Show full text]
  • Fossil Fish Fauna Is Uncertain, but May Be As Old As Late Frasnian, Rather Than Famennian As Was Previously Assumed
    Records of the Western AlIstralwll MllSClIlI1 Supplement No. 57: 139--150 (1999). Preliminary report on the biostratigraphy of new placoderm discoveries in the Hervey Group (Upper Devonian) of central New South Wales Gavin C. Young Department of Geology, The Australian National University, Canberra, ACT 0200; email: [email protected] Abstract - Re-mapping during 1994-96 of the Upper Devonian on the Parkes and Grenfell 1:100,000 map sheets was the first systematic field examination of this area by an experienced vertebrate palaeontologist. This resulted in the discovery of some 40 new fossil localities (mostly fish) at various horizons within the Hervey Group. Two new fish occurrences, in sediments associated with the underlying Dulladerry Volcanics, require an age revision from Early to late Middle Devonian for the termination of Devonian volcanism in central New South Wales. The age of the Canowindra fossil fish fauna is uncertain, but may be as old as late Frasnian, rather than Famennian as was previously assumed. Correlations across the Lachlan River are clarified, and a new locality for the sinolepid antiarch Grenfellaspis is reported from near the top of the Bumberry Formation. A fish fauna from higher in the sequence includes an antiarch with an armour 1-2 m long, of comparable size to similar material from South China, which supports a latest Devonian Asian connection with East Gondwana. Preliminary analysis of faunal content is used to propose a provisional succession of six faunal zones, to improve the resolution on the Late Devonian part of the macrovertebrate zonation for East Gondwana. INTRODUCTION west of the Canowindra locality (Figure 1).
    [Show full text]