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Miedema F, Bindellini G, Dal Sasso C, Scheyer TM, Maxwell EE. Ontogenetic variation in the cranium of Mixosaurus cornalianus, with implications for the evolution of ichthyosaurian cranial development. SWISS JOURNAL OF PALAEONTOLOGY 2023; 142:27. [PMID: 37810205 PMCID: PMC10556136 DOI: 10.1186/s13358-023-00289-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 08/27/2023] [Indexed: 10/10/2023]
Abstract
Relatively complete ontogenetic series are comparatively rare in the vertebrate fossil record. This can create biases in our understanding of morphology and evolution, since immaturity can represent a source of unrecognized intraspecific variation in both skeletal anatomy and ecology. In the extinct marine reptile clade Ichthyopterygia, ontogenetic series were widely studied only in some Jurassic genera, while the ontogeny of the oldest and most basal members of the clade is very poorly understood. Here, we investigate cranial ontogeny in Mixosaurus cornalianus, from the Middle Triassic Besano Formation of the Swiss and Italian Alps. This small-bodied taxon is represented by a wealth of material from multiple size classes, including fetal material. This allows us to assess ontogenetic changes in cranial morphology, and identify stages in the ontogenetic trajectory where divergence with more derived ichthyosaurs has occurred. Early ontogenetic stages of Mixosaurus show developmental patterns that are reminiscent of the presumed ancestral (early diverging sauropsid) condition. This is prominently visible in the late fetal stage in both the basioccipital, which shows morphology akin to basal tubera, and in the postorbital, which has a triradiate head. The ontogenetic trajectory of at least some of the cranial elements of Mixosaurus is therefore likely still very akin to the ancestral condition, even though the adult cranium diverges from the standard diapsid morphology. Supplementary Information The online version contains supplementary material available at 10.1186/s13358-023-00289-z.
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Affiliation(s)
- Feiko Miedema
- Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, 70191 Stuttgart, Germany
- Hohenheim University, Schloss Hohenheim 1A, 70599 Stuttgart, Germany
| | - Gabriele Bindellini
- Dipartimento di Scienze della Terra, Università degli Studi di Milano, Milan, Italy
- Dipartimento di Scienze della Terra, Sapienza Università di Roma, Rome, Italy
| | | | - Torsten M. Scheyer
- Universität Zürich, Paläontologisches Institut, Karl Schmid-Strasse 4, 8006 Zürich, Switzerland
| | - Erin E. Maxwell
- Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, 70191 Stuttgart, Germany
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2
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Wolniewicz AS, Shen Y, Li Q, Sun Y, Qiao Y, Chen Y, Hu YW, Liu J. An armoured marine reptile from the Early Triassic of South China and its phylogenetic and evolutionary implications. eLife 2023; 12:e83163. [PMID: 37551884 PMCID: PMC10499374 DOI: 10.7554/elife.83163] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 08/07/2023] [Indexed: 08/09/2023] Open
Abstract
Sauropterygia was a taxonomically and ecomorphologically diverse clade of Mesozoic marine reptiles spanning the Early Triassic to the Late Cretaceous. Sauropterygians are traditionally divided into two groups representing two markedly different body plans - the short-necked, durophagous Placodontia and the long-necked Eosauropterygia - whereas Saurosphargidae, a small clade of armoured marine reptiles, is generally considered as the sauropterygian sister-group. However, the early evolutionary history of sauropterygians and their phylogenetic relationships with other groups within Diapsida are still incompletely understood. Here, we report a new saurosphargid from the Early Triassic (Olenekian) of South China - Prosaurosphargis yingzishanensis gen. et sp. nov. - representing the earliest known occurrence of the clade. An updated phylogenetic analysis focussing on the interrelationships among diapsid reptiles recovers saurosphargids as nested within sauropterygians, forming a clade with eosauropterygians to the exclusion of placodonts. Furthermore, a clade comprising Eusaurosphargis and Palatodonta is recovered as the sauropterygian sister-group within Sauropterygomorpha tax. nov. The phylogenetic position of several Early and Middle Triassic sauropterygians of previously uncertain phylogenetic affinity, such as Atopodentatus, Hanosaurus, Majiashanosaurus, and Corosaurus, is also clarified, elucidating the early evolutionary assembly of the sauropterygian body plan. Finally, our phylogenetic analysis supports the placement of Testudines and Archosauromorpha within Archelosauria, a result strongly corroborated by molecular data, but only recently recovered in a phylogenetic analysis using a morphology-only dataset. Our study provides evidence for the rapid diversification of sauropterygians in the aftermath of the Permo-Triassic mass extinction event and emphasises the importance of broad taxonomic sampling in reconstructing phylogenetic relationships among extinct taxa.
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Affiliation(s)
- Andrzej S Wolniewicz
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
- Institute of Paleobiology, Polish Academy of SciencesWarsawPoland
| | - Yuefeng Shen
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
| | - Qiang Li
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
- Section Paleontology, Institute of Geosciences, University of BonnBonnGermany
| | - Yuanyuan Sun
- Chengdu Center, China Geological Survey (Southwest China Innovation Center for Geosciences)ChengduChina
| | - Yu Qiao
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
| | - Yajie Chen
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
| | - Yi-Wei Hu
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
| | - Jun Liu
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
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3
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Ren J, Jiang H, Xiang K, Sullivan C, He Y, Cheng L, Han F. A new basal ichthyosauromorph from the Lower Triassic (Olenekian) of Zhebao, Guangxi Autonomous Region, South China. PeerJ 2022; 10:e13209. [PMID: 35415016 PMCID: PMC8995025 DOI: 10.7717/peerj.13209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 03/10/2022] [Indexed: 01/12/2023] Open
Abstract
Here we describe a newly discovered basal ichthyosauromorph from the Lower Triassic of South China, Baisesaurus robustus gen. et sp. nov. The only known specimen of this new species was collected from the Lower Triassic (Olenekian) Luolou Formation in the Zhebao region of Baise City, on the northwest margin of the Nanpanjiang Basin, and comprises a partial skeleton including the ribs, the gastralia, a limb element, 12 centra, and seven neural arches. Comparisons to a wide variety of Early Triassic marine reptiles show Baisesaurus robustus to be a basal ichthyosauromorph based on the following features: neural arches lack transverse processes; dorsal ribs are slender, and not pachyostotic even proximally; and median gastral elements have long, sharp anterior processes. The limb element is long and robust, and is most likely to be a radius. Baisesaurus robustus is large (estimated length more than 3 m) relative to early ichthyosauromorphs previously discovered in China, and shares noteworthy morphological similarities with Utatsusaurus hataii, particularly with regard to body size and the morphology of the probable radius. Baisesaurus robustus also represents the first record of an Early Triassic ichthyosauromorph from Guangxi Autonomous Region, extending the known geographic distribution of ichthyosauromorphs in South China.
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Affiliation(s)
- Jicheng Ren
- School of Li Siguang, China University of Geosciences (Wuhan), Wuhan, Hubei Province, China
| | - Haishui Jiang
- School of Earth Sciences, China University of Geosciences (Wuhan), Wuhan, Hubei Province, China
| | - Kunpeng Xiang
- Guizhou Geological Survey, Guiyang, Guizhou Province, China
| | - Corwin Sullivan
- Department of Biological Sciences, University of Alberta, Edmonton, Canada,Philip J. Currie Dinosaur Museum, Wembley, Canada
| | - Yongzhong He
- Guizhou Geological Survey, Guiyang, Guizhou Province, China
| | - Long Cheng
- Wuhan Centre of China Geological Survey, Wuhan, China
| | - Fenglu Han
- School of Earth Sciences, China University of Geosciences (Wuhan), Wuhan, Hubei Province, China
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4
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Nakajima Y, Shigeta Y, Houssaye A, Zakharov YD, Popov AM, Sander PM. Early Triassic ichthyopterygian fossils from the Russian Far East. Sci Rep 2022; 12:5546. [PMID: 35365703 PMCID: PMC8976075 DOI: 10.1038/s41598-022-09481-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Accepted: 03/23/2022] [Indexed: 11/19/2022] Open
Abstract
Ichthyopterygia is a major clade of reptiles that colonized the ocean after the end-Permian mass extinction, with the oldest fossil records found in early Spathian substage (late Olenekian, late Early Triassic) strata in the western USA. Here, we describe reptilian remains found in situ in the early Spathian Neocolumbites insignis ammonoid zone of South Primorye in the Russian Far East. Specimen NSM PV 23854 comprises fragmentary axial elements exhibiting a combination of morphological characteristics typical of Ichthyopterygia. The cylindrical centra suggest that the specimen represents a basal ichthyopterygian, and its size is comparable to that of Utatsusaurus. Specimen NSM PV 24995 is represented by a single limb bone, which is tentatively identified as an ichthyopterygian humerus. With a body length of approximately 5 m estimated from the humeral length, NSM PV 24995 represents one of the largest specimens of early Spathian marine reptiles known to date. Such size variation among the earliest ichthyopterygians might suggest an explosive diversification in size immediately after the end-Permian mass extinction. Both vertebrae and humerus specimens exhibit an extremely cancellous inner structure, suggesting a high degree of aquatic adaptation in ichthyopterygians, despite their short history of evolution in the ocean.
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Affiliation(s)
- Yasuhisa Nakajima
- Department of Natural Sciences, Faculty of Science and Engineering, Tokyo City University, 1-28-1 Tamazutsumi, Setagaya-ku, Tokyo, 158-8557, Japan.
| | - Yasunari Shigeta
- Department of Geology and Paleontology, National Museum of Nature and Science, 4-1-1 Amakubo, Tsukuba, Ibaraki, 305-0005, Japan
| | - Alexandra Houssaye
- Département Adaptations du Vivant, UMR 7179 CNRS/Muséum National d'Histoire Naturelle, 57 rue Cuvier CP-55, 75005, Paris, France
| | - Yuri D Zakharov
- Far Eastern Geological Institute, Russian Academy of Sciences, Far Eastern Branch, Stoletiya Prospect 159, Vladivostok, Russia, 690022
| | - Alexander M Popov
- Far Eastern Geological Institute, Russian Academy of Sciences, Far Eastern Branch, Stoletiya Prospect 159, Vladivostok, Russia, 690022
| | - P Martin Sander
- Section Paleontology, Institute of Geosciences, University of Bonn, 53115, Bonn, Germany
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5
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Sander PM, Griebeler EM, Klein N, Juarbe JV, Wintrich T, Revell LJ, Schmitz L. Early giant reveals faster evolution of large body size in ichthyosaurs than in cetaceans. Science 2021; 374:eabf5787. [PMID: 34941418 DOI: 10.1126/science.abf5787] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- P Martin Sander
- Abteilung Paläontologie, Institut für Geowissenschaften, Universität Bonn, 53115 Bonn, Germany.,The Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA 90007, USA
| | - Eva Maria Griebeler
- Institut für Organismische und Molekulare Evolutionsbiologie, Evolutionäre Ökologie, Johannes Gutenberg-Universität Mainz, 55099 Mainz, Germany
| | - Nicole Klein
- Abteilung Paläontologie, Institut für Geowissenschaften, Universität Bonn, 53115 Bonn, Germany
| | - Jorge Velez Juarbe
- Department of Mammalogy, Natural History Museum of Los Angeles County, Los Angeles, CA 90007, USA
| | - Tanja Wintrich
- Abteilung Paläontologie, Institut für Geowissenschaften, Universität Bonn, 53115 Bonn, Germany.,Anatomisches Institut, Universität Bonn, 53115 Bonn, Germany
| | - Liam J Revell
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA.,Universidad Católica de la Santísima Concepción, Concepción, Chile
| | - Lars Schmitz
- The Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA 90007, USA.,W.M. Keck Science Department of Claremont McKenna, Scripps, and Pitzer Colleges, Claremont, CA 91711, USA
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6
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Gutarra S, Rahman IA. The locomotion of extinct secondarily aquatic tetrapods. Biol Rev Camb Philos Soc 2021; 97:67-98. [PMID: 34486794 DOI: 10.1111/brv.12790] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 08/14/2021] [Accepted: 08/18/2021] [Indexed: 02/06/2023]
Abstract
The colonisation of freshwater and marine ecosystems by land vertebrates has repeatedly occurred in amphibians, reptiles, birds and mammals over the course of 300 million years. Functional interpretations of the fossil record are crucial to understanding the forces shaping these evolutionary transitions. Secondarily aquatic tetrapods have acquired a suite of anatomical, physiological and behavioural adaptations to locomotion in water. However, much of this information is lost for extinct clades, with fossil evidence often restricted to osteological data and a few extraordinary specimens with soft tissue preservation. Traditionally, functional morphology in fossil secondarily aquatic tetrapods was investigated through comparative anatomy and correlation with living functional analogues. However, in the last two decades, biomechanics in palaeobiology has experienced a remarkable methodological shift. Anatomy-based approaches are increasingly rigorous, informed by quantitative techniques for analysing shape. Moreover, the incorporation of physics-based methods has enabled objective tests of functional hypotheses, revealing the importance of hydrodynamic forces as drivers of evolutionary innovation and adaptation. Here, we present an overview of the latest research on the locomotion of extinct secondarily aquatic tetrapods, with a focus on amniotes, highlighting the state-of-the-art experimental approaches used in this field. We discuss the suitability of these techniques for exploring different aspects of locomotory adaptation, analysing their advantages and limitations and laying out recommendations for their application, with the aim to inform future experimental strategies. Furthermore, we outline some unexplored research avenues that have been successfully deployed in other areas of palaeobiomechanical research, such as the use of dynamic models in feeding mechanics and terrestrial locomotion, thus providing a new methodological synthesis for the field of locomotory biomechanics in extinct secondarily aquatic vertebrates. Advances in imaging technology and three-dimensional modelling software, new developments in robotics, and increased availability and awareness of numerical methods like computational fluid dynamics make this an exciting time for analysing form and function in ancient vertebrates.
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Affiliation(s)
- Susana Gutarra
- School of Earth Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol, BS8 1TQ, U.K.,Department of Earth Sciences, the Natural History Museum, Cromwell Road, London, U.K
| | - Imran A Rahman
- Department of Earth Sciences, the Natural History Museum, Cromwell Road, London, U.K.,Oxford University Museum of Natural History, Parks Road, Oxford, OX1 3PW, U.K
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7
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Yin YL, Ji C, Zhou M. The anatomy of the palate in Early Triassic Chaohusaurus brevifemoralis (Reptilia: Ichthyosauriformes) based on digital reconstruction. PeerJ 2021; 9:e11727. [PMID: 34268013 PMCID: PMC8269639 DOI: 10.7717/peerj.11727] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 06/15/2021] [Indexed: 12/20/2022] Open
Abstract
The palatal anatomy of ichthyosauriforms remains largely unknown. Here, the complete palate of the early-branching ichthyosauriform Chaohusaurus brevifemoralis is reconstructed and described for the first time with the assistance of high-resolution X-ray computed tomography (CT) scanning on the basis of the three-dimensionally preserved skull of its paratype (GMPKU-P-3086) from the Lower Triassic of South China. The reconstruction reveals new palatal features of C. brevifemoralis. The palatine contacts the jugal directly, which is observed in ichthyosauriforms for the first time. A single row of denticles is present on each side of the palate. The vomer exceeds the anterior and posterior margins of the internal naris. The pterygoid is posterior to the internal naris. The epipterygoid is present and the ectopterygoid is absent.
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Affiliation(s)
- Ya-Lei Yin
- Department of Geology and Geological Museum, Peking University, Beijing, China
| | - Cheng Ji
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing, China
| | - Min Zhou
- Department of Geology and Geological Museum, Peking University, Beijing, China
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8
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Bindellini G, Wolniewicz AS, Miedema F, Scheyer TM, Dal Sasso C. Cranial anatomy of Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 (Reptilia: Ichthyosauria) from the Middle Triassic Besano Formation of Monte San Giorgio, Italy/Switzerland: taxonomic and palaeobiological implications. PeerJ 2021; 9:e11179. [PMID: 33996277 PMCID: PMC8106916 DOI: 10.7717/peerj.11179] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 03/08/2021] [Indexed: 12/20/2022] Open
Abstract
Besanosaurus leptorhynchus Dal Sasso & Pinna, 1996 was described on the basis of a single fossil excavated near Besano (Italy) nearly three decades ago. Here, we re-examine its cranial osteology and assign five additional specimens to B. leptorhynchus, four of which were so far undescribed. All of the referred specimens were collected from the Middle Triassic outcrops of the Monte San Giorgio area (Italy/Switzerland) and are housed in various museum collections in Europe. The revised diagnosis of the taxon includes the following combination of cranial characters: extreme longirostry; an elongate frontal not participating in the supratemporal fenestra; a prominent 'triangular process' of the quadrate; a caudoventral exposure of the postorbital on the skull roof; a prominent coronoid (preglenoid) process of the surangular; tiny conical teeth with coarsely-striated crown surfaces and deeply-grooved roots; mesial maxillary teeth set in sockets; distal maxillary teeth set in a short groove. All these characters are shared with the holotype of Mikadocephalus gracilirostris Maisch & Matzke, 1997, which we consider as a junior synonym of B. leptorhynchus. An updated phylogenetic analysis, which includes revised scores for B. leptorhynchus and several other shastasaurids, recovers B. leptorhynchus as a basal merriamosaurian, but it is unclear if Shastasauridae form a clade, or represent a paraphyletic group. The inferred body length of the examined specimens ranges from 1 m to about 8 m. The extreme longirostry suggests that B. leptorhynchus primarily fed on small and elusive prey, feeding lower in the food web than an apex predator: a novel ecological specialisation never reported before the Anisian in a large diapsid. This specialization might have triggered an increase of body size and helped to maintain low competition among the diverse ichthyosaur fauna of the Besano Formation.
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Affiliation(s)
- Gabriele Bindellini
- Dipartimento di Scienze della Terra “Ardito Desio”, Università degli Studi di Milano, Milano, Italy
| | | | - Feiko Miedema
- Staatliches Museum für Naturkunde Stuttgart, Stuttgart, Germany
- Paläontologisches Institut und Museum, Universität Zürich, Zürich, Switzerland
| | - Torsten M. Scheyer
- Paläontologisches Institut und Museum, Universität Zürich, Zürich, Switzerland
| | - Cristiano Dal Sasso
- Sezione di Paleontologia dei Vertebrati, Museo di Storia Naturale di Milano, Milano, Italy
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9
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Motani R, Vermeij GJ. Ecophysiological steps of marine adaptation in extant and extinct non-avian tetrapods. Biol Rev Camb Philos Soc 2021; 96:1769-1798. [PMID: 33904243 DOI: 10.1111/brv.12724] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 04/10/2021] [Accepted: 04/13/2021] [Indexed: 12/11/2022]
Abstract
Marine reptiles and mammals are phylogenetically so distant from each other that their marine adaptations are rarely compared directly. We reviewed ecophysiological features in extant non-avian marine tetrapods representing 31 marine colonizations to test whether there is a common pattern across higher taxonomic groups, such as mammals and reptiles. Marine adaptations in tetrapods can be roughly divided into aquatic and haline adaptations, each of which seems to follow a sequence of three steps. In combination, these six categories exhibit five steps of marine adaptation that apply across all clades except snakes: Step M1, incipient use of marine resources; Step M2, direct feeding in the saline sea; Step M3, water balance maintenance without terrestrial fresh water; Step M4, minimized terrestrial travel and loss of terrestrial feeding; and Step M5, loss of terrestrial thermoregulation and fur/plumage. Acquisition of viviparity is not included because there is no known case where viviparity evolved after a tetrapod lineage colonized the sea. A similar sequence is found in snakes but with the haline adaptation step (Step M3) lagging behind aquatic adaptation (haline adaptation is Step S5 in snakes), most likely because their unique method of water balance maintenance requires a supply of fresh water. The same constraint may limit the maximum body size of fully marine snakes. Steps M4 and M5 in all taxa except snakes are associated with skeletal adaptations that are mechanistically linked to relevant ecophysiological features, allowing assessment of marine adaptation steps in some fossil marine tetrapods. We identified four fossil clades containing members that reached Step M5 outside of stem whales, pinnipeds, sea cows and sea turtles, namely Eosauropterygia, Ichthyosauromorpha, Mosasauroidea, and Thalattosuchia, while five other clades reached Step M4: Saurosphargidae, Placodontia, Dinocephalosaurus, Desmostylia, and Odontochelys. Clades reaching Steps M4 and M5, both extant and extinct, appear to have higher species diversity than those only reaching Steps M1 to M3, while the total number of clades is higher for the earlier steps. This suggests that marine colonizers only diversified greatly after they minimized their use of terrestrial resources, with many lineages not reaching these advanced steps. Historical patterns suggest that a clade does not advance to Steps M4 and M5 unless these steps are reached early in the evolution of the clade. Intermediate forms before a clade reached Steps M4 and M5 tend to become extinct without leaving extant descendants or fossil evidence. This makes it difficult to reconstruct the evolutionary history of marine adaptation in many clades. Clades that reached Steps M4 and M5 tend to last longer than other marine tetrapod clades, sometimes for more than 100 million years.
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Affiliation(s)
- Ryosuke Motani
- Department of Earth and Planetary Sciences, University of California, Davis, Davis, CA, 95616, U.S.A
| | - Geerat J Vermeij
- Department of Earth and Planetary Sciences, University of California, Davis, Davis, CA, 95616, U.S.A
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10
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Jiang DY, Motani R, Tintori A, Rieppel O, Ji C, Zhou M, Wang X, Lu H, Li ZG. Evidence Supporting Predation of 4-m Marine Reptile by Triassic Megapredator. iScience 2020; 23:101347. [PMID: 32822565 PMCID: PMC7520894 DOI: 10.1016/j.isci.2020.101347] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 06/09/2020] [Accepted: 07/04/2020] [Indexed: 11/28/2022] Open
Abstract
Air-breathing marine predators have been essential components of the marine ecosystem since the Triassic. Many of them are considered the apex predators but without direct evidence-dietary inferences are usually based on circumstantial evidence, such as tooth shape. Here we report a fossil that likely represents the oldest evidence for predation on megafauna, i.e., animals equal to or larger than humans, by marine tetrapods-a thalattosaur (∼4 m in total length) in the stomach of a Middle Triassic ichthyosaur (∼5 m). The predator has grasping teeth yet swallowed the body trunk of the prey in one to several pieces. There were many more Mesozoic marine reptiles with similar grasping teeth, so megafaunal predation was likely more widespread than presently conceived. Megafaunal predation probably started nearly simultaneously in multiple lineages of marine reptiles in the Illyrian (about 242-243 million years ago).
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Affiliation(s)
- Da-Yong Jiang
- Laboratory of Orogenic Belt and Crustal Evolution, Ministry of Education; Department of Geology and Geological Museum, School of Earth and Space Sciences, Peking University, Yiheyuan Street. 5, Beijing 100871, People's Republic of China
| | - Ryosuke Motani
- Department of Earth and Planetary Sciences, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Andrea Tintori
- Dipartimento di Scienze della Terra, Università degli Studi di Milano, Via Mangiagalli, 34-20133 Milano, Italy
| | - Olivier Rieppel
- Integrative Research Center, The Field Museum, Chicago, IL 60605-2496, USA
| | - Cheng Ji
- Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Beijing East Road 39, Nanjing, Jiangsu 210008, People's Republic of China
| | - Min Zhou
- Laboratory of Orogenic Belt and Crustal Evolution, Ministry of Education; Department of Geology and Geological Museum, School of Earth and Space Sciences, Peking University, Yiheyuan Street. 5, Beijing 100871, People's Republic of China
| | - Xue Wang
- Laboratory of Orogenic Belt and Crustal Evolution, Ministry of Education; Department of Geology and Geological Museum, School of Earth and Space Sciences, Peking University, Yiheyuan Street. 5, Beijing 100871, People's Republic of China
| | - Hao Lu
- Laboratory of Orogenic Belt and Crustal Evolution, Ministry of Education; Department of Geology and Geological Museum, School of Earth and Space Sciences, Peking University, Yiheyuan Street. 5, Beijing 100871, People's Republic of China
| | - Zhi-Guang Li
- The Geoscience Museum, Hebei GEO University, No. 136 East Huai'an Road, Shijiazhuang, Hebei 050031, People's Republic of China
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11
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Young MT, Sachs S, Abel P, Foffa D, Herrera Y, Kitson JJN. Convergent evolution and possible constraint in the posterodorsal retraction of the external nares in pelagic crocodylomorphs. Zool J Linn Soc 2020. [DOI: 10.1093/zoolinnean/zlaa021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
AbstractAmongst Mesozoic marine reptiles, metriorhynchid crocodylomorphs were unique in evolving into pelagically adapted forms with little-to-no posterodorsal retraction of the external nares. Narial retraction is a common adaptation seen in sustained swimmers, notably occurring during cetacean evolution. Mesosaurids and the basalmost known members of ichthyosauriforms, thalattosaurians, saurosphargids, sauropterygians, pleurosaurids and mosasauroids had the external nares divided by an ossified bar, bound by multiple cranial bones and were positioned back from the tip of the rostrum. However, metriorhynchids evolved from taxa with a single external naris bound solely by the premaxilla, and positioned near the tip of an elongate rostrum. We posit that metriorhynchids were uniquely disadvantaged in evolving into sustained swimmers. Herein we describe three Late Jurassic metriorhynchid cranial rostra that display differing degrees of narial retraction. In our new phylogenetic analyses, the backwards migration of the narial fossa posterior margin occurred independently at least four times in Metriorhynchidae, whereas the backwards migration of the anterior margin only occurred twice. Although Rhacheosaurini share the backwards migration of the anterior and posterior narial margins, posterodorsal retraction occurred differently along three lineages. This culminated in the Early Cretaceous, where a rhacheosaurin evolved nares bound by the premaxilla and maxilla, and significantly posterodorsally retracted.
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Affiliation(s)
- Mark T Young
- School of GeoSciences, Grant Institute, The King’s Buildings, University of Edinburgh, Edinburgh, UK
| | - Sven Sachs
- Naturkunde-Museum Bielefeld, Abteilung Geowissenschaften, Bielefeld, Germany
| | - Pascal Abel
- Senckenberg Centre for Human Evolution and Palaeoenvironment, Eberhard-Karls-University Tübingen, Tübingen, Germany
| | - Davide Foffa
- Department of Natural Sciences, National Museums Scotland, Edinburgh, UK
| | - Yanina Herrera
- División Paleontología Vertebrados, Museo de La Plata, Facultad de Ciencias Naturales y Museo, UNLP, CONICET, La Plata, Argentina
| | - James J N Kitson
- School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, UK
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12
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Huang JD, Motani R, Jiang DY, Ren XX, Tintori A, Rieppel O, Zhou M, Hu YC, Zhang R. Repeated evolution of durophagy during ichthyosaur radiation after mass extinction indicated by hidden dentition. Sci Rep 2020; 10:7798. [PMID: 32385319 PMCID: PMC7210957 DOI: 10.1038/s41598-020-64854-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 04/17/2020] [Indexed: 01/19/2023] Open
Abstract
Marine tetrapods quickly diversified and were established as marine top predators after the end-Permian Mass extinction (EPME). Ichthyosaurs were the forerunner of this rapid radiation but the main drivers of the diversification are poorly understood. Cartorhynchus lenticarpus is a basal ichthyosauriform with the least degree of aquatic adaptation, holding a key to identifying such a driver. The unique specimen appeared edentulous based on what was exposed but a CT scanning revealed that the species indeed had rounded teeth that are nearly perpendicular to the jaw rami, and thus completely concealed in lateral view. There are three dental rows per jaw ramus, and the root lacks infoldings of the dentine typical of ichthyopterygians. The well-developed and worn molariform dentition with three tooth rows supports the previous inference that the specimen is not of a juvenile. The premaxilla and the corresponding part of the dentary are edentulous. Molariform dentition evolved three to five times independently within Ichthyosauriformes in the Early and Middle Triassic. Convergent exploitation of hard-shelled invertebrates by different subclades of ichthyosauriforms likely fueled the rapid taxonomic diversification of the group after EPME.
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Affiliation(s)
- Jian-Dong Huang
- Department of Research, Anhui Geological Museum, Jiahe Road 999, Hefei, Anhui, 230031, China
| | - Ryosuke Motani
- Department of Earth and Planetary Sciences, University of California, One Shields Avenue, 95616, Davis, California, USA.
| | - Da-Yong Jiang
- Department of Geology and Geological Museum, Peking University, Yiheyuan Street. 5, Beijing, 100871, P.R. China.,State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology), Chinese Academy of Science, Nanjing, 210008, P. R. China
| | - Xin-Xin Ren
- Department of Research, Anhui Geological Museum, Jiahe Road 999, Hefei, Anhui, 230031, China
| | - Andrea Tintori
- Dipartimento di Scienze della Terra, Università degli Studi di Milano, Via Mangiagalli 34-20133, Milano, Italy
| | - Olivier Rieppel
- Center of Integrative Research, The Field Museum, Chicago, IL, 60605-2496, USA
| | - Min Zhou
- Department of Geology and Geological Museum, Peking University, Yiheyuan Street. 5, Beijing, 100871, P.R. China
| | - Yuan-Chao Hu
- Department of Research, Anhui Geological Museum, Jiahe Road 999, Hefei, Anhui, 230031, China
| | - Rong Zhang
- Department of Research, Anhui Geological Museum, Jiahe Road 999, Hefei, Anhui, 230031, China
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13
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Gutarra S, Moon BC, Rahman IA, Palmer C, Lautenschlager S, Brimacombe AJ, Benton MJ. Effects of body plan evolution on the hydrodynamic drag and energy requirements of swimming in ichthyosaurs. Proc Biol Sci 2020; 286:20182786. [PMID: 30836867 PMCID: PMC6458325 DOI: 10.1098/rspb.2018.2786] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Ichthyosaurs are an extinct group of fully marine tetrapods that were well adapted to aquatic locomotion. During their approximately 160 Myr existence, they evolved from elongate and serpentine forms into stockier, fish-like animals, convergent with sharks and dolphins. Here, we use computational fluid dynamics (CFD) to quantify the impact of this transition on the energy demands of ichthyosaur swimming for the first time. We run computational simulations of water flow using three-dimensional digital models of nine ichthyosaurs and an extant functional analogue, a bottlenose dolphin, providing the first quantitative evaluation of ichthyosaur hydrodynamics across phylogeny. Our results show that morphology did not have a major effect on the drag coefficient or the energy cost of steady swimming through geological time. We show that even the early ichthyosaurs produced low levels of drag for a given volume, comparable to those of a modern dolphin, and that deep ‘torpedo-shaped’ bodies did not reduce the cost of locomotion. Our analysis also provides important insight into the choice of scaling parameters for CFD applied to swimming mechanics, and underlines the great influence of body size evolution on ichthyosaur locomotion. A combination of large bodies and efficient swimming modes lowered the cost of steady swimming as ichthyosaurs became increasingly adapted to a pelagic existence.
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Affiliation(s)
- Susana Gutarra
- 1 School of Earth Sciences, University of Bristol , Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ , UK
| | - Benjamin C Moon
- 1 School of Earth Sciences, University of Bristol , Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ , UK
| | - Imran A Rahman
- 2 Oxford University Museum of Natural History , Parks Road, Oxford OX1 3PW , UK
| | - Colin Palmer
- 1 School of Earth Sciences, University of Bristol , Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ , UK
| | - Stephan Lautenschlager
- 3 School of Geography, Earth and Environmental Sciences, University of Birmingham , Birmingham B15 2TT , UK
| | - Alison J Brimacombe
- 1 School of Earth Sciences, University of Bristol , Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ , UK
| | - Michael J Benton
- 1 School of Earth Sciences, University of Bristol , Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ , UK
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14
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Bennett SC. Reassessment of the Triassic archosauriform Scleromochlus taylori: neither runner nor biped, but hopper. PeerJ 2020; 8:e8418. [PMID: 32117608 PMCID: PMC7035874 DOI: 10.7717/peerj.8418] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 12/17/2019] [Indexed: 11/20/2022] Open
Abstract
The six known specimens of Scleromochlus taylori and casts made from their negative impressions were examined to reassess the osteological evidence that has been used to interpret Scleromochlus's locomotion and phylogenetic relationships. It was found that the trunk was dorsoventrally compressed. The upper temporal fenestra was on the lateral surface of skull and two-thirds the size of the lower, the jaw joint posteriorly placed with short retroarticular process, and teeth short and subconical, but no evidence of external nares or antorbital fossae was found. The posterior trunk was covered with ~20 rows of closely spaced transversely elongate dorsal osteoderms. The coracoid was robust and elongate. The acetabulum was imperforate and the femoral head hemispherical and only weakly inturned such that the hip joint was unsuited to swinging in a parasagittal plane. The presence of four distal tarsals is confirmed. The marked disparity of tibial and fibular shaft diameters and of proximal tarsal dimensions indicates that the larger proximal tarsal is the astragalus and the significantly smaller tarsal is the calcaneum. The astragalus and calcaneum bear little resemblance to those of Lagosuchus, and the prominent calcaneal tuber confirms that the ankle was crurotarsal. There is no evidence that preserved body and limb postures are unnatural, and most specimens are preserved in what is interpreted as a typical sprawling resting pose. A principal component analysis of skeletal measurements of Scleromochlus and other vertebrates of known locomotor type found Scleromochlus to plot with frogs, and that finding combined with skeletal morphology suggests Scleromochlus was a sprawling quadrupedal hopper. Phylogenetic analyses found that Scleromochlus was not an ornithodiran, but was either within the Doswelliidae or outside the clade consisting of the most recent common ancestor of the Erythrosuchidae and Archosauria and all its descendants.
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15
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Moon BC, Stubbs TL. Early high rates and disparity in the evolution of ichthyosaurs. Commun Biol 2020; 3:68. [PMID: 32054967 PMCID: PMC7018711 DOI: 10.1038/s42003-020-0779-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 01/07/2020] [Indexed: 12/02/2022] Open
Abstract
How clades diversify early in their history is integral to understanding the origins of biodiversity and ecosystem recovery following mass extinctions. Moreover, diversification can represent evolutionary opportunities and pressures following ecosystem changes. Ichthyosaurs, Mesozoic marine reptiles, appeared after the end-Permian mass extinction and provide opportunities to assess clade diversification in a changed world. Using recent cladistic data, skull length data, and the most complete phylogenetic trees to date for the group, we present a combined disparity, morphospace, and evolutionary rates analysis that reveals the tempo and mode of ichthyosaur morphological evolution through 160 million years. Ichthyosaur evolution shows an archetypal early burst trend, driven by ecological opportunity in Triassic seas, and an evolutionary bottleneck leading to a long-term reduction in evolutionary rates and disparity. This is represented consistently across all analytical methods by a Triassic peak in ichthyosaur disparity and evolutionary rates, and morphospace separation between Triassic and post-Triassic taxa.
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Affiliation(s)
- Benjamin C Moon
- Palaeobiology Research Group, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK.
| | - Thomas L Stubbs
- Palaeobiology Research Group, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol, BS8 1TQ, UK
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16
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Huang JD, Motani R, Jiang DY, Tintori A, Rieppel O, Zhou M, Ren XX, Zhang R. The new ichthyosauriform Chaohusaurus brevifemoralis (Reptilia, Ichthyosauromorpha) from Majiashan, Chaohu, Anhui Province, China. PeerJ 2019; 7:e7561. [PMID: 31565558 PMCID: PMC6741286 DOI: 10.7717/peerj.7561] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 07/27/2019] [Indexed: 11/20/2022] Open
Abstract
A new species of ichthyosauriform is recognized based on 20 specimens, including nearly complete skeletons, and named Chaohusaurus brevifemoralis. A part of the specimens was previously identified as Chaohusaurus chaoxianensis and is herein reassigned to the new species. The new species differs from existing species of Chaohusaurus in a suite of features, such as the bifurcation of the caudal peak neural spine and a short femur relative to trunk length. The specimens include both complete and partially disarticulated skulls, allowing rigorous scrutiny of cranial sutures. For example, the squamosal does not participate in the margin of the upper temporal fenestra despite previous interpretations. Also, the frontal unequivocally forms a part of the anterior margin of the upper temporal fenestra, forming the most medial part of the anterior terrace. The skull of the holotype largely retains three-dimensionality with the scleral rings approximately in situ, revealing that the eyeball was uncovered in two different directions, that is, laterally and slightly dorsally through the main part of the orbit, and dorsally through the medial extension of the orbit into the skull roof. This skull construction is likely a basal feature of Ichthyosauromorpha. Phylogenetic analyses place the new species as a sister taxon of Chaohusaurus chaoxianensis.
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Affiliation(s)
- Jian-Dong Huang
- Department of Research, Anhui Geological Museum, Hefei, Anhui, People's Republic of China
| | - Ryosuke Motani
- Department of Earth and Planetary Sciences, University of California, Davis, CA, USA
| | - Da-Yong Jiang
- Department of Geology, Peking University, Beijing, People's Republic of China
| | - Andrea Tintori
- Dipartimento di Scienze della Terra, Università degli Studi di Milano, Milano, Italia
| | - Olivier Rieppel
- Center of Integrative Research, The Field Museum, Chicago, IL, USA
| | - Min Zhou
- Department of Geology, Peking University, Beijing, People's Republic of China
| | - Xin-Xin Ren
- Department of Research, Anhui Geological Museum, Hefei, Anhui, People's Republic of China
| | - Rong Zhang
- Department of Research, Anhui Geological Museum, Hefei, Anhui, People's Republic of China
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17
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Cheng L, Motani R, Jiang DY, Yan CB, Tintori A, Rieppel O. Early Triassic marine reptile representing the oldest record of unusually small eyes in reptiles indicating non-visual prey detection. Sci Rep 2019; 9:152. [PMID: 30679783 PMCID: PMC6345829 DOI: 10.1038/s41598-018-37754-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 12/12/2018] [Indexed: 11/25/2022] Open
Abstract
The end-Permian mass extinction (EPME) led to reorganization of marine predatory communities, through introduction of air-breathing top predators, such as marine reptiles. We report two new specimens of one such marine reptile, Eretmorhipis carrolldongi, from the Lower Triassic of Hubei, China, revealing superficial convergence with the modern duckbilled platypus (Ornithorhynchus anatinus), a monotreme mammal. Apparent similarities include exceptionally small eyes relative to the body, snout ending with crura with a large internasal space, housing a bone reminiscent of os paradoxum, a mysterious bone of platypus, and external grooves along the crura. The specimens also have a rigid body with triangular bony blades protruding from the back. The small eyes likely played reduced roles during foraging in this animal, as with extant amniotes (group containing mammals and reptiles) with similarly small eyes. Mechanoreceptors on the bill of the animal were probably used for prey detection instead. The specimens represent the oldest record of amniotes with extremely reduced visual capacity, utilizing non-visual cues for prey detection. The discovery reveals that the ecological diversity of marine predators was already high in the late Early Triassic, and challenges the traditional view that the ecological diversification of marine reptiles was delayed following the EPME.
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Affiliation(s)
- Long Cheng
- Wuhan Centre of China Geological Survey, Wuhan, Hubei, 430023, P. R. China.
| | - Ryosuke Motani
- Department of Earth and Planetary Sciences, University of California, Davis, CA, 95616, USA.
| | - Da-Yong Jiang
- Laboratory of Orogenic Belt and Crustal Evolution, MOE, Department of Geology and Geological Museum, Peking University, Yiheyuan Str. 5, Beijing, 100871, P. R. China
| | - Chun-Bo Yan
- Wuhan Centre of China Geological Survey, Wuhan, Hubei, 430023, P. R. China
| | - Andrea Tintori
- Dipartimento di Scienze della Terra, Università degli Studi di Milano, Via Mangiagalli, 34-20133, Milano, Italy
| | - Olivier Rieppel
- Center of Integrative Research, The Field Museum, Chicago, IL, 60605-2496, USA
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18
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Separating sexual dimorphism from other morphological variation in a specimen complex of fossil marine reptiles (Reptilia, Ichthyosauriformes, Chaohusaurus). Sci Rep 2018; 8:14978. [PMID: 30297861 PMCID: PMC6175944 DOI: 10.1038/s41598-018-33302-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 09/17/2018] [Indexed: 11/27/2022] Open
Abstract
The Early Triassic Chaohu Fauna from Anhui Province, China, contains the oldest record of Mesozoic marine reptiles, such as Cartorhynchus and Sclerocormus. Most specimens from the fauna belong to the ichthyosauriform Chaohusaurus, more specifically resembling C. chaoxianensis. However, a wide range of morphological variation exists within about 40 skeletons that have been prepared, likely reflecting mixed signals from both sexual and taxonomic differences. We test whether the sexual and taxonomic signals are separable based on quantification, aided by the knowledge of sexual dimorphism in extant marine tetrapods. There are two different suites of dimorphism that divide the specimens differently from each other yet consistently within each suite, resulting in four morphotypes in combination, likely representing two sexes of two taxa. Presumed males have larger ‘organ of prehension’ sensu Darwin, specifically limbs in the present case, for a given body length. This sexing criterion is supported by the only specimen of a gravid female, which belongs to the morphotype with short limbs. Males also have larger skulls for the trunk length compared to females. This study demonstrates that sexual and taxonomic signals are separable in fossil reptiles, with a sufficient sample size and careful analyses.
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19
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Lomax DR, De la Salle P, Massare JA, Gallois R. A giant Late Triassic ichthyosaur from the UK and a reinterpretation of the Aust Cliff 'dinosaurian' bones. PLoS One 2018; 13:e0194742. [PMID: 29630618 PMCID: PMC5890986 DOI: 10.1371/journal.pone.0194742] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 03/08/2018] [Indexed: 11/21/2022] Open
Abstract
The largest reported ichthyosaurs lived during the Late Triassic (~235–200 million years ago), and isolated, fragmentary bones could be easily mistaken for those of dinosaurs because of their size. We report the discovery of an isolated bone from the lower jaw of a giant ichthyosaur from the latest Triassic of Lilstock, Somerset, UK. It documents that giant ichthyosaurs persisted well into the Rhaetian Stage, and close to the time of the Late Triassic extinction event. This specimen has prompted the reinterpretation of several large, roughly cylindrical bones from the latest Triassic (Rhaetian Stage) Westbury Mudstone Formation from Aust Cliff, Gloucestershire, UK. We argue here that the Aust bones, previously identified as those of dinosaurs or large terrestrial archosaurs, are jaw fragments from giant ichthyosaurs. The Lilstock and Aust specimens might represent the largest ichthyosaurs currently known.
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Affiliation(s)
- Dean R. Lomax
- School of Earth and Environmental Sciences, The University of Manchester, Oxford Road, Manchester, United Kingdom
- * E-mail:
| | - Paul De la Salle
- The Etches Collection–Museum of Jurassic Marine Life, Dorset, United Kingdom
| | - Judy A. Massare
- Department of the Earth Sciences, State University of New York, College at Brockport, Brockport, NY, United States of America
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20
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Motani R, Jiang DY, Tintori A, Ji C, Huang JD. Pre- versus post-mass extinction divergence of Mesozoic marine reptiles dictated by time-scale dependence of evolutionary rates. Proc Biol Sci 2018; 284:rspb.2017.0241. [PMID: 28515201 DOI: 10.1098/rspb.2017.0241] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 04/24/2017] [Indexed: 12/11/2022] Open
Abstract
The fossil record of a major clade often starts after a mass extinction even though evolutionary rates, molecular or morphological, suggest its pre-extinction emergence (e.g. squamates, placentals and teleosts). The discrepancy is larger for older clades, and the presence of a time-scale-dependent methodological bias has been suggested, yet it has been difficult to avoid the bias using Bayesian phylogenetic methods. This paradox raises the question of whether ecological vacancies, such as those after mass extinctions, prompt the radiations. We addressed this problem by using a unique temporal characteristic of the morphological data and a high-resolution stratigraphic record, for the oldest clade of Mesozoic marine reptiles, Ichthyosauromorpha. The evolutionary rate was fastest during the first few million years of ichthyosauromorph evolution and became progressively slower over time, eventually becoming six times slower. Using the later slower rates, estimates of divergence time become excessively older. The fast, initial rate suggests the emergence of ichthyosauromorphs after the end-Permian mass extinction, matching an independent result from high-resolution stratigraphic confidence intervals. These reptiles probably invaded the sea as a new ecosystem was formed after the end-Permian mass extinction. Lack of information on early evolution biased Bayesian clock rates.
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Affiliation(s)
- Ryosuke Motani
- Department of Earth and Planetary Sciences, University of California, One Shields Avenue, Davis, CA 95616, USA
| | - Da-Yong Jiang
- Department of Geology and Geological Museum, Peking University, Yiheyuan Street 5, Beijing 100871, People's Republic of China.,State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology), 39 East Beijing Road, Nanjing 210008, People's Republic of China
| | - Andrea Tintori
- Dipartimento di Scienze della Terra, Università degli Studi di Milano, Via Mangiagalli 34-20133 Milano, Italy
| | - Cheng Ji
- Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, People's Republic of China
| | - Jian-Dong Huang
- Department of Research, Anhui Geological Museum, Jiahe Road 999, Hefei, Anhui 230031, People's Republic of China
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21
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Wood R, Erwin DH. Innovation not recovery: dynamic redox promotes metazoan radiations. Biol Rev Camb Philos Soc 2017; 93:863-873. [PMID: 29034568 DOI: 10.1111/brv.12375] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 09/11/2017] [Accepted: 09/13/2017] [Indexed: 11/29/2022]
Abstract
Environmental fluctuations in redox may reinforce rather than hinder evolutionary transitions, such that variability in near-surface oceanic oxygenation can promote morphological evolution and novelty. Modern, low-oxygen regions are heterogeneous and dynamic habitats that support low diversity and are inhabited by opportunistic and non-skeletal metazoans. We note that several major radiation episodes follow protracted or repeating intervals (>1 million years) of persistent and dynamic shallow marine redox (oceanic anoxic events). These are also often associated with short-lived mass-extinction events (<0.5 million years) where skeletal benthic incumbents are removed, and surviving or newly evolved benthos initially inhabit transient oxic habitats. We argue that such intervals create critical opportunities for the generation of evolutionary novelty, followed by innovation and diversification. We develop a general model for redox controls on the distribution and structure of the shallow marine benthos in a dominantly anoxic world, and compile data from the terminal Ediacaran-mid-Cambrian (∼560-509 Ma), late Cambrian-Ordovician (∼500-445 Ma), and Permo-Triassic (∼255-205 Ma) to test these predictions. Assembly of phylogenetic data shows that prolonged and widespread anoxic intervals indeed promoted morphological novelty in soft-bodied benthos, providing the ancestral stock for subsequently skeletonized lineages to appear as innovations once oxic conditions became widespread and stable, in turn promoting major evolutionary diversification. As a result, we propose that so-called 'recovery' intervals after mass extinctions might be better considered as 'innovation' intervals.
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Affiliation(s)
- Rachel Wood
- School of GeoSciences, University of Edinburgh, James Hutton Road, Edinburgh, EH9 3FE, U.K
| | - Douglas H Erwin
- Department of Paleobiology, Smithsonian Institution, Washington, DC 20013-7012, U.S.A
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22
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23
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Delsett LL, Roberts AJ, Druckenmiller PS, Hurum JH. A New Ophthalmosaurid (Ichthyosauria) from Svalbard, Norway, and Evolution of the Ichthyopterygian Pelvic Girdle. PLoS One 2017; 12:e0169971. [PMID: 28121995 PMCID: PMC5266267 DOI: 10.1371/journal.pone.0169971] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 12/24/2016] [Indexed: 01/11/2023] Open
Abstract
In spite of a fossil record spanning over 150 million years, pelvic girdle evolution in Ichthyopterygia is poorly known. Here, we examine pelvic girdle size relationships using quantitative methods and new ophthalmosaurid material from the Slottsmøya Member Lagerstätte of Svalbard, Norway. One of these new specimens, which preserves the most complete ichthyosaur pelvic girdle from the Cretaceous, is described herein as a new taxon, Keilhauia nui gen. et sp. nov. It represents the most complete Berriasian ichthyosaur known and the youngest yet described from the Slottsmøya Member. It is diagnosed on the basis of two autapomorphies from the pelvic girdle, including an ilium that is anteroposteriorly expanded at its dorsal end and an ischiopubis that is shorter or subequal in length to the femur, as well as a unique character combination. The Slottsmøya Member Lagerstätte ichthyosaurs are significant in that they represent a diverse assemblage of ophthalmosaurids that existed immediately preceding and across the Jurassic–Cretaceous boundary. They also exhibit considerable variation in pelvic girdle morphology, and expand the known range in size variation of pelvic girdle elements in the clade.
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Affiliation(s)
| | - Aubrey J. Roberts
- Natural History Museum, University of Oslo, Oslo, Norway
- The National Oceanography Centre, Department of Ocean and Earth Science, University of Southampton, Southampton, Hampshire, United Kingdom
| | - Patrick S. Druckenmiller
- University of Alaska Museum, Fairbanks, Alaska
- Department of Geoscience, University of Alaska Fairbanks, Fairbanks, Alaska
| | - Jørn H. Hurum
- Natural History Museum, University of Oslo, Oslo, Norway
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