1
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Miller E, Lee HW, Abzhanov A, Evers SW. The topological organization of the turtle cranium is constrained and conserved over long evolutionary timescales. Anat Rec (Hoboken) 2024; 307:2713-2748. [PMID: 38102921 DOI: 10.1002/ar.25356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/30/2023] [Accepted: 11/14/2023] [Indexed: 12/17/2023]
Abstract
The cranium of turtles (Testudines) is characterized by the secondary reduction of temporal fenestrae and loss of cranial joints (i.e., characteristics of anapsid, akinetic skulls). Evolution and ontogeny of the turtle cranium are associated with shape changes. Cranial shape variation among Testudines can partially be explained by dietary and functional adaptations (neck retraction), but it is unclear if cranial topology shows similar ecomorphological signal, or if it is decoupled from shape evolution. We assess the topological arrangement of cranial bones (i.e., number, relative positioning, connections), using anatomical network analysis. Non-shelled stem turtles have similar cranial arrangements to archosauromorph outgroups. Shelled turtles (Testudinata) evolve a unique cranial organization that is associated with bone losses (e.g., supratemporal, lacrimal, ectopterygoid) and an increase in complexity (i.e., densely and highly interconnected skulls with low path lengths between bones), resulting from the closure of skull openings and establishment of unusual connections such as a parietal-pterygoid contact in the secondary braincase. Topological changes evolutionarily predate many shape changes. Topological variation and taxonomic morphospace discrimination among crown turtles are low, indicating that cranial topology may be constrained. Observed variation results from repeated losses of nonintegral bones (i.e., premaxilla, nasal, epipterygoid, quadratojugal), and changes in temporal emarginations and palate construction. We observe only minor ontogenetic changes. Topology is not influenced by diet and habitat, contrasting cranial shape. Our results indicate that turtles have a unique cranial topology among reptiles that is conserved after its initial establishment, and shows that cranial topology and shape have different evolutionary histories.
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Affiliation(s)
- Eve Miller
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Berkshire, UK
- Natural History Museum, London, UK
| | - Hiu Wai Lee
- Department of Earth Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Arkhat Abzhanov
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Berkshire, UK
- Natural History Museum, London, UK
| | - Serjoscha W Evers
- Department of Geosciences, University of Fribourg, Fribourg, Switzerland
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2
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Menon JCL, Brinkman DB, Hermanson G, Joyce WG, Evers SW. New insights into the early morphological evolution of sea turtles by re-investigation of Nichollsemys baieri, a three-dimensionally preserved fossil stem chelonioid from the Campanian of Alberta, Canada. SWISS JOURNAL OF PALAEONTOLOGY 2024; 143:27. [PMID: 39006951 PMCID: PMC11245440 DOI: 10.1186/s13358-024-00323-8] [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: 03/19/2024] [Accepted: 06/03/2024] [Indexed: 07/16/2024]
Abstract
The early evolution of Pan-Chelonioidea (sea turtles) is poorly understood. This is in part due to the rarity of undeformed skulls of definitive early stem chelonioids. In this work, we redescribe the holotype of Nichollsemys baieri using µCT scans and segmentations of the skull. This fossil is the best 3D preserved skull of any Campanian sea turtle, and includes partial "soft tissue" preservation. Nichollsemys is morphologically similar but clearly distinct from Toxochelys spp., and both show a mosaic of plesiomorphic and derived chelonioid features. The internal cranial anatomy documents the presence of derived characters in Nichollsemys baieri that are absent in Toxochelys spp., such as the loss of the epipterygoids and the rod-like shape of the rostrum basisphenoidale. Among the numerous plesiomorphic characters is the presence of a splenial bone, which was unnoticed before. An updated phylogenetic analysis retrieves Nichollsemys baieri as a non-protostegid early stem chelonioid in a slightly more crownward position than Toxochelys latiremis. Our phylogeny includes macrobaenids and protostegids as pan-chelonioids, and we find unorthodox results for dermochelyids. Thus, although Nichollsemys baieri provides important new insights into the early morphological evolution of sea turtles, much work remains to be done. As a completely 3D preserved specimen, we included Nichollsemys baieri into a recent landmark-based skull shape dataset of turtles. Morphospace analysis reveals an intermediate position between cryptodires and crown chelonioids. Based on these data, we also predict that Nichollsemys baieri was still capable of neck retraction, constraining the loss of this trait to more crownward pan-chelonioids. Supplementary Information The online version contains supplementary material available at 10.1186/s13358-024-00323-8.
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Affiliation(s)
- Juliette C. L. Menon
- Department of Geosciences, University of Fribourg, Chemin du Musée 6, 1700 Fribourg, Switzerland
| | - Donald B. Brinkman
- Royal Tyrrell Museum of Palaeontology, Drumheller, AB Canada
- Department of Biological Sciences, University of Alberta, Edmonton, AB Canada
| | - Guilherme Hermanson
- Department of Geosciences, University of Fribourg, Chemin du Musée 6, 1700 Fribourg, Switzerland
| | - Walter G. Joyce
- Department of Geosciences, University of Fribourg, Chemin du Musée 6, 1700 Fribourg, Switzerland
| | - Serjoscha W. Evers
- Department of Geosciences, University of Fribourg, Chemin du Musée 6, 1700 Fribourg, Switzerland
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3
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Mauel C, Leicht L, Broshko Y, Yaryhin O, Werneburg I. Chondrocranial anatomy of Testudo hermanni (Testudinidae, Testudines) with a comparison to other turtles. J Morphol 2024; 285:e21747. [PMID: 38956884 DOI: 10.1002/jmor.21747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 06/04/2024] [Accepted: 06/05/2024] [Indexed: 07/04/2024]
Abstract
Using histological cross-sections, the chondrocranium anatomy was reconstructed for two developmental stages of Hermann's tortoise (Testudo hermanni). The morphology differs from the chondrocrania of most other turtles by a process above the ectochoanal cartilage with Pelodiscus sinensis being the only other known species with such a structure. The anterior and posterior processes of the tectum synoticum are better developed than in most other turtles and an ascending process of the palatoquadrate is missing, which is otherwise only the case in pleurodiran turtles. The nasal region gets proportionally larger during development. We interpret the enlargement of the nasal capsules as an adaption to increase the surface area of the olfactory epithelium for better perception of volant odors. Elongation of the nasal capsules in trionychids, in contrast, is unlikely to be related to olfaction, while it is ambiguous in the case of Sternotherus odoratus. However, we have to conclude that research on chondrocranium anatomy is still at its beginning and more comprehensive detailed descriptions in relation to other parts of the anatomy are needed before providing broad-scale ecological and phylogenetic interpretations.
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Affiliation(s)
- Carola Mauel
- Fachbereich Biologie, Universität Tübingen, Tübingen, Germany
- Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Universität Bonn, Bonn, Germany
| | - Luca Leicht
- Fachbereich Biologie, Universität Tübingen, Tübingen, Germany
- Senckenberg Center for Human Evolution and Palaeoenvironment (SHEP), Universität Tübingen, Tübingen, Germany
| | - Yevhenii Broshko
- Faculty of Natural Sciences, Faculty of Natural Sciences, Kryvyi Rih State Pedagogical University, Kryvyi Rih, Ukraine
| | - Oleksandr Yaryhin
- Schmalhausen Institute of Zoology NAS of Ukraine, Department of Evolutionary Morphology, Kyiv, Ukraine
| | - Ingmar Werneburg
- Senckenberg Center for Human Evolution and Palaeoenvironment (SHEP), Universität Tübingen, Tübingen, Germany
- Fachbereich Geowissenschaften, Universität Tübingen, Tübingen, Germany
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4
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Evers SW. Mandibular anatomy of the paracryptodire Glyptops ornatus supports active hunting behavior in a Jurassic turtle. Anat Rec (Hoboken) 2024; 307:2007-2017. [PMID: 37747271 DOI: 10.1002/ar.25320] [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: 07/31/2023] [Revised: 08/28/2023] [Accepted: 08/31/2023] [Indexed: 09/26/2023]
Abstract
The mandible of turtles is rich in osteological characters that are relevant for systematic purposes. Shape variation additionally reflects upon various feeding strategies and are thus informative for the palaeoecological interpretation of extinct species based on fossils. The mandibular anatomy of non-baenid paracryptodires has so far been undescribed. Based on digital segmentation of a computed tomography scan, I herein describe the mandible of the pleurosternid paracryptodire Glyptops ornatus. This taxon has a slender and gracile jaw, with weakly developed muscle attachment sites for adductor muscles (i.e., adductor fossa, coronoid process, and retroarticular process) and strongly reduced triturating ridges. These features are typical for suction-feeding aquatic hunters, thereby contrasting with the robust, durophagous-adapted mandibles of many baenid or compsemydid paracryptodires. In addition, the mandible of G. ornatus is characterized by the presence of a large splenial with a dorsal splenial-dentary contact, the presence of a splenial foramen, and the strong reduction of the foramen dentofaciale majus and the absence of a posterior intermandibular foramen.
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Affiliation(s)
- Serjoscha W Evers
- Department of Geosciences, University of Fribourg, Fribourg, Switzerland
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5
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Jorgewich-Cohen G, Werneburg I, Jobbins M, Ferreira GS, Taylor MD, Bastiaans D, Sánchez-Villagra MR. Morphological Diversity of Turtle Hyoid Apparatus is Linked to Feeding Behavior. Integr Org Biol 2024; 6:obae014. [PMID: 38741667 PMCID: PMC11090499 DOI: 10.1093/iob/obae014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 04/03/2024] [Accepted: 05/01/2024] [Indexed: 05/16/2024] Open
Abstract
The hyoid apparatus of tetrapods is highly diverse in its morphology. It plays an important role in feeding, breathing, sound production, and various other behaviors. Among turtles, the diversity of the hyoid apparatus has been recurrently linked to their habitat. The ossification of the hyoid corpus is often the main trait used in correlations with "niche" occupancy, an ossified corpus being associated with aquatic environments and a cartilaginous corpus with terrestrial life. Most studies conducted so far have focused on species belonging to Testudinoidea, the clade that occupies the biggest diversity of habitats (i.e., terrestrial, semi-terrestrial, and aquatic animals), while other turtle lineages have been largely understudied. We assessed the adult anatomy of the hyoid apparatus of 92 turtle species from all "families", together with ossification sequences from embryological series of 11 species, some described for the first time here. Using nearly 40 different discrete anatomical characters, we discuss the evolutionary patterns and the biological significance of morphological transformations in the turtle hyoid elements. Morphological changes are strongly associated to feeding modes, with several instances of convergent evolution within and outside the Testudines clade, and are not as strongly connected to habitat as previously thought. Some of the hyoid character states we describe are diagnostic of specific turtle clades, thus providing phylogenetically relevant information.
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Affiliation(s)
- G Jorgewich-Cohen
- Department of Paleontology, University of Zurich, 8006 Zurich, Switzerland
| | - I Werneburg
- Senckenberg Centre for Human Evolution and Palaeoenvironment an der Universität Tübingen, Tübingen, Germany
- Fachbereich Geowissenshcaten dr Universität Tübingen, 72074 Tübingen, Germany
| | - M Jobbins
- Department of Paleontology, University of Zurich, 8006 Zurich, Switzerland
| | - G S Ferreira
- Senckenberg Centre for Human Evolution and Palaeoenvironment an der Universität Tübingen, Tübingen, Germany
- Fachbereich Geowissenshcaten dr Universität Tübingen, 72074 Tübingen, Germany
| | - M D Taylor
- School of Biological Sciences, The University of Western Australia, Perth, WA 6009, Australia
- The UWA Oceans Institute, The University of Western Australia, Perth, WA 6009, Australia
| | - D Bastiaans
- Department of Paleontology, University of Zurich, 8006 Zurich, Switzerland
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6
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Werneburg I, Preuschoft H. Evolution of the temporal skull openings in land vertebrates: A hypothetical framework on the basis of biomechanics. Anat Rec (Hoboken) 2024; 307:1559-1593. [PMID: 38197580 DOI: 10.1002/ar.25371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 12/04/2023] [Accepted: 12/05/2023] [Indexed: 01/11/2024]
Abstract
The complex constructions of land vertebrate skulls have inspired a number of functional analyses. In the present study, we provide a basic view on skull biomechanics and offer a framework for more general observations using advanced modeling approaches in the future. We concentrate our discussion on the cranial openings in the temporal skull region and work out two major, feeding-related factors that largely influence the shape of the skull. We argue that (1) the place where the most forceful biting is conducted and (2) the handling of resisting food (sideward movements) constitute the formation and shaping of either one or two temporal arcades surrounding these openings. Diversity in temporal skull anatomy among amniotes can be explained by specific modulations of these factors with different amounts of acting forces which inevitably lead to deposition or reduction of bone material. For example, forceful anterior bite favors an infratemporal bar, whereas forceful posterior bite favors formation of an upper temporal arcade. Transverse forces (inertia and resistance of seized objects) as well as neck posture also influence the shaping of the temporal region. Considering their individual skull morphotypes, we finally provide hypotheses on the feeding adaptation in a variety of major tetrapod groups. We did not consider ligaments, internal bone structure, or cranial kinesis in our considerations. Involving those in quantitative tests of our hypotheses, such as finite element system synthesis, will provide a comprehensive picture on cranial mechanics and evolution in the future.
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Affiliation(s)
- Ingmar Werneburg
- Paläontologische Sammlung, Fachbereich Geowissenschaften, Eberhard Karls Universität, Tübingen, Germany
- Senckenberg Center for Human Evolution and Palaeoenvironment, Eberhard Karls Universität, Tübingen, Germany
| | - Holger Preuschoft
- Funktionelle Morphologie im Anatomischen Institut, Ruhr-Universität Bochum, Bochum, Germany
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Ferreira GS, Nascimento ER, Cadena EA, Cozzuol MA, Farina BM, Pacheco MLAF, Rizzutto MA, Langer MC. The latest freshwater giants: a new Peltocephalus (Pleurodira: Podocnemididae) turtle from the Late Pleistocene of the Brazilian Amazon. Biol Lett 2024; 20:20240010. [PMID: 38471564 PMCID: PMC10932709 DOI: 10.1098/rsbl.2024.0010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 02/15/2024] [Indexed: 03/14/2024] Open
Abstract
Overkill of large mammals is recognized as a key driver of Pleistocene megafaunal extinctions in the Americas and Australia. While this phenomenon primarily affected mega-mammals, its impact on large Quaternary reptiles has been debated. Freshwater turtles, due to the scarcity of giant forms in the Quaternary record, have been largely neglected in such discussions. Here we present a new giant podocnemidid turtle, Peltocephalus maturin sp. nov., from the Late Pleistocene Rio Madeira Formation in the Brazilian Amazon, that challenges this assumption. Morphological and phylogenetic analyses of the holotype, a massive partial lower jaw, reveal close affinities to extant Amazonian species and suggest an omnivorous diet. Body size regressions indicate Pe. maturin possibly reached about 180 cm in carapace length and is among the largest freshwater turtles ever found. This finding presents the latest known occurrence of giant freshwater turtles, hinting at coexistence with early human inhabitants in the Amazon.
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Affiliation(s)
- G. S. Ferreira
- Senckenberg Centre for Human Evolution and Palaeoenvironment at the Eberhard Karls Universität Tübingen, Tübingen, Germany
- Geowissenschaften Fachbereich, Eberhard Karls Universität Tübingen, Tübingen, Germany
| | - E. R. Nascimento
- Centro de Biologia Experimental (CIBEBI), Programa de Mestrado e Doutorado em Geografia, Universidade Federal de Rondônia (UNIR), Porto Velho, Brazil
| | - E. A. Cadena
- Facultad de Ciencias Naturales, Grupo de Investigación Paleontología Neotropical Tradicional y Molecular (PaleoNeo), Universidad del Rosario, Bogotá, Colombia
- Smithsonian Tropical Research Institute, Panamá, Panama
| | - M. A. Cozzuol
- Departamento de Zoologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - B. M. Farina
- Department of Biology, University of Fribourg, Fribourg, Switzerland
- Swiss Institute of Bioinformatics, Fribourg, Switzerland
| | - M. L. A. F. Pacheco
- Laboratório de Paleobiologia e Astrobiologia, Universidade Federal de São Carlos, Sorocaba, Brazil
| | - M. A. Rizzutto
- Instituto de Física, Universidade de São Paulo, São Paulo, Brazil
| | - M. C. Langer
- Departamento de Biologia, Universidade de São Paulo, Ribeirão Preto, Brazil
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8
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Farina BM, Godoy PL, Benson RBJ, Langer MC, Ferreira GS. Turtle body size evolution is determined by lineage-specific specializations rather than global trends. Ecol Evol 2023; 13:e10201. [PMID: 37384241 PMCID: PMC10293707 DOI: 10.1002/ece3.10201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 05/26/2023] [Accepted: 06/01/2023] [Indexed: 06/30/2023] Open
Abstract
Organisms display a considerable variety of body sizes and shapes, and macroevolutionary investigations help to understand the evolutionary dynamics behind such variations. Turtles (Testudinata) show great body size disparity, especially when their rich fossil record is accounted for. We explored body size evolution in turtles, testing which factors might influence the observed patterns and evaluating the existence of long-term directional trends. We constructed the most comprehensive body size dataset for the group to date, tested for correlation with paleotemperature, estimated ancestral body sizes, and performed macroevolutionary model-fitting analyses. We found no evidence for directional body size evolution, even when using very flexible models, thereby rejecting the occurrence of Cope's rule. We also found no significant effect of paleotemperature on overall through-time body size patterns. In contrast, we found a significant influence of habitat preference on turtle body size. Freshwater turtles display a rather homogeneous body size distribution through time. In contrast, terrestrial and marine turtles show more pronounced variation, with terrestrial forms being restricted to larger body sizes, up to the origin of testudinids in the Cenozoic, and marine turtles undergoing a reduction in body size disparity after the extinctions of many groups in the mid-Cenozoic. Our results, therefore, suggest that long-term, generalized patterns are probably explained by factors specific to certain groups and related at least partly to habitat use.
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Affiliation(s)
- Bruna M. Farina
- Department of BiologyUniversity of FribourgFribourgSwitzerland
- Swiss Institute of BioinformaticsFribourgSwitzerland
- Laboratório de Paleontologia de Ribeirão PretoUniversidade de São PauloRibeirão PretoBrazil
| | - Pedro L. Godoy
- Laboratório de Paleontologia de Ribeirão PretoUniversidade de São PauloRibeirão PretoBrazil
- Department of Anatomical SciencesStony Brook UniversityStony BrookNew YorkUSA
| | - Roger B. J. Benson
- Division of PaleontologyAmerican Museum of Natural HistoryNew YorkNew YorkUSA
| | - Max C. Langer
- Laboratório de Paleontologia de Ribeirão PretoUniversidade de São PauloRibeirão PretoBrazil
| | - Gabriel S. Ferreira
- Senckenberg Centre for Human Evolution and Palaeoenvironment (HEP)Eberhard Karls Universität TübingenTübingenGermany
- Fachbereich GeowissenschaftenEberhard Karls Universität TübingenTübingenGermany
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Ke Y, Rahman IA, Song H, Hu J, Niu K, Lou F, Li H, Han F. A new species of Nanhsiungchelys (Testudines: Cryptodira: Nanhsiungchelyidae) from the Upper Cretaceous of Nanxiong Basin, China. PeerJ 2023; 11:e15439. [PMID: 37273532 PMCID: PMC10237181 DOI: 10.7717/peerj.15439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 04/28/2023] [Indexed: 06/06/2023] Open
Abstract
Nanhsiungchelyidae are a group of large turtles that lived in Asia and North America during the Cretaceous. Here we report a new species of nanhsiungchelyid, Nanhsiungchelys yangi sp. nov., from the Upper Cretaceous of Nanxiong Basin, China. The specimen consists of a well-preserved skull and lower jaw, as well as the anterior parts of the carapace and plastron. The diagnostic features of Nanhsiungchelys include a large entire carapace length (∼55.5 cm), a network of sculptures consisting of pits and ridges on the surface of the skull and shell, shallow cheek emargination and temporal emargination, deep nuchal emargination, and a pair of anterolateral processes on the carapace. However, Nanhsiungchelys yangi differs from the other species of Nanhsiungchelys mainly in having a triangular-shaped snout (in dorsal view) and wide anterolateral processes on the carapace. Additionally, some other characteristics (e.g., the premaxilla is higher than wide, the maxilla is unseen in dorsal views, a small portion of the maxilla extends posterior and ventral of the orbit, and the parietal is bigger than the frontal) are strong evidence to distinguish Nanhsiungchelys yangi from Nanhsiungchelys wuchingensis. A phylogenetic analysis of nanhsiungchelyids places Nanhsiungchelys yangi and Nanhsiungchelys wuchingensis as sister taxa. Nanhsiungchelys yangi and some other nanhsiungchelyids bear distinct anterolateral processes on the carapace, which have not been reported in any extant turtles and may have played a role in protecting the head. The Nanxiong Basin was extremely hot during the Late Cretaceous, and so we suggest that nanhsiungchelyids might have immersed themselves in mud or water to avoid the heat, similar to some extant tortoises. If they were capable of swimming, our computer simulations of fluid flow suggest the anterolateral processes could have reduced drag during locomotion.
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Affiliation(s)
- Yuzheng Ke
- School of Earth Science, China University of Geosciences (Wuhan), Wuhan, Hubei, People’s Republic of China
| | - Imran A. Rahman
- The Natural History Museum, London, United Kingdom
- Oxford University Museum of Natural History, Oxford, United Kingdom
| | - Hanchen Song
- School of Earth Science, China University of Geosciences (Wuhan), Wuhan, Hubei, People’s Republic of China
| | - Jinfeng Hu
- School of Earth Science, China University of Geosciences (Wuhan), Wuhan, Hubei, People’s Republic of China
| | - Kecheng Niu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian, People’s Republic of China
- Yingliang Stone Natural History Museum, Nan’an, Fujian, People’s Republic of China
| | - Fasheng Lou
- Jiangxi Geological Survey and Exploration Institute, Nanchang, Jiangxi, People’s Republic of China
| | - Hongwei Li
- Guangdong Geological Survey Institute, Guangzhou, Guangdong, People’s Republic of China
| | - Fenglu Han
- School of Earth Science, China University of Geosciences (Wuhan), Wuhan, Hubei, People’s Republic of China
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10
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Evers SW, Chapelle KEJ, Joyce WG. Cranial and mandibular anatomy of Plastomenus thomasii and a new time-tree of trionychid evolution. SWISS JOURNAL OF PALAEONTOLOGY 2023; 142:1. [PMID: 36941994 PMCID: PMC10020266 DOI: 10.1186/s13358-023-00267-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
UNLABELLED Trionychid (softshell) turtles have a peculiar bauplan, which includes shell reductions and cranial elongation. Despite a rich fossil record dating back to the Early Cretaceous, the evolutionary origin of the trionychid bauplan is poorly understood, as even old fossils show great anatomical similarities to extant species. Documenting structural detail of fossil trionychids may help resolve the evolutionary history of the group. Here, we study the cranial and mandibular anatomy of Plastomenus thomasii using µCT scanning. Plastomenus thomasii belongs to the Plastomenidae, a long-lived (Santonian-Eocene) clade with uncertain affinities among trionychid subclades. The skulls of known plastomenids are characterized by unusual features otherwise not known among trionychids, such as extremely elongated, spatulate mandibular symphyses. We use anatomical observations for updated phylogenetic analyses using both parsimony and Bayesian methods. There is strong support across methods for stem-cyclanorbine affinities for plastomenids. The inclusion of stratigraphic data in our Bayesian analysis indicates that a range of Cretaceous Asian fossils including Perochelys lamadongensis may be stem-trionychids, suggesting that many features of trionychid anatomy evolved prior to the appearance of the crown group. Divergence time estimates from Bayesian tip-dating for the origin of crown Trionychia (134.0 Ma) and Pan-Trionychidae (123.8 Ma) constrain the evolutionary time span during which the trionychid bauplan has evolved to a range of < 11 million years. Bayesian rate estimation implies high morphological rates during early softshell turtle evolution. If correct, plastomenids partially fill the stratigraphic gap which results from shallow divergence times of crown cyclanorbines during the late Eocene. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1186/s13358-023-00267-5.
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Affiliation(s)
- Serjoscha W. Evers
- Department of Geosciences, University of Fribourg, Chemin du Musée 6, 1700 Fribourg, Switzerland
| | - Kimberley E. J. Chapelle
- Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192 USA
| | - Walter G. Joyce
- Department of Geosciences, University of Fribourg, Chemin du Musée 6, 1700 Fribourg, Switzerland
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11
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Lowi-Merri TM, Demuth OE, Benito J, Field DJ, Benson RBJ, Claramunt S, Evans DC. Reconstructing locomotor ecology of extinct avialans: a case study of Ichthyornis comparing sternum morphology and skeletal proportions. Proc Biol Sci 2023; 290:20222020. [PMID: 36883281 PMCID: PMC9993061 DOI: 10.1098/rspb.2022.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 02/08/2023] [Indexed: 03/09/2023] Open
Abstract
Avian skeletal morphology is associated with locomotor function, including flight style, swimming and terrestrial locomotion, and permits informed inferences on locomotion in extinct taxa. The fossil taxon Ichthyornis (Avialae: Ornithurae) has long been regarded as highly aerial, with flight similar to terns or gulls (Laridae), and skeletal features resembling foot-propelled diving adaptations. However, rigorous testing of locomotor hypotheses has yet to be performed on Ichthyornis, despite its notable phylogenetic position as one of the most crownward stem birds. We analysed separate datasets of three-dimensional sternal shape (geometric morphometrics) and skeletal proportions (linear measurements across the skeleton), to examine how well these data types predict locomotor traits in Neornithes. We then used this information to infer locomotor capabilities of Ichthyornis. We find strong support for both soaring and foot-propelled swimming capabilities in Ichthyornis. Further, sternal shape and skeletal proportions provide complementary information on avian locomotion: skeletal proportions allow better predictions of the capacity for flight, whereas sternal shape predicts variation in more specific locomotor abilities such as soaring, foot-propelled swimming and escape burst flight. These results have important implications for future studies of extinct avialan ecology and underscore the importance of closely considering sternum morphology in investigations of fossil bird locomotion.
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Affiliation(s)
- Talia M. Lowi-Merri
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, Canada M5S 2C6
| | - Oliver E. Demuth
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
- Structure and Motion Laboratory, Royal Veterinary College, Hatfield, UK
| | - Juan Benito
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
- Department of Biology and Biochemistry, Milner Centre for Evolution, University of Bath, Bath, UK
| | - Daniel J. Field
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
- Museum of Zoology, University of Cambridge, Cambridge, UK
| | - Roger B. J. Benson
- Division of Paleontology, American Museum of Natural History, 200 Central Park West, New York, NY 12004, USA
- Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, UK
| | - Santiago Claramunt
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, Canada M5S 2C6
| | - David C. Evans
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2
- Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, Canada M5S 2C6
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