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Rollot Y, Evers SW, Ferreira GS, Girard LC, Werneburg I, Joyce WG. Skull osteology, neuroanatomy, and jaw-related myology of the pig-nosed turtle Carettochelys insculpta (Cryptodira, Trionychia). Anat Rec (Hoboken) 2024; 307:2966-3020. [PMID: 38421128 DOI: 10.1002/ar.25411] [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: 11/10/2023] [Revised: 02/05/2024] [Accepted: 02/06/2024] [Indexed: 03/02/2024]
Abstract
The osteology, neuroanatomy, and musculature are known for most primary clades of turtles (i.e., "families"), but knowledge is still lacking for one particular clade, the Carettochelyidae. Carettochelyids are represented by only one living taxon, the pig-nosed turtle Carettochelys insculpta. Here, we use micro-computed tomography of osteological and contrast-enhanced stained specimens to describe the cranial osteology, neuroanatomy, circulatory system, and jaw musculature of Carettochelys insculpta. The jaw-related myology is described in detail for the first time for this taxon, including m. zygomaticomandibularis, a muscular unit only found in trionychians. We also document a unique arterial pattern for the internal carotid artery and its subordinate branches and provide an extensive list of osteological ontogenetic differences. The present work provides new insights into the craniomandibular anatomy of turtles and will allow a better understanding of the evolutionary history of the circulatory system of trionychians and intraspecific variation among turtles.
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Affiliation(s)
- Yann Rollot
- Department of Geosciences, University of Fribourg, Fribourg, Switzerland
| | - Serjoscha W Evers
- Department of Geosciences, University of Fribourg, Fribourg, Switzerland
| | - Gabriel S Ferreira
- Fachbereich Geowissenschaften, Universität Tübingen, Tübingen, Germany
- Senckenberg Centre for Human Evolution and Palaeoenvironment, Tübingen, Germany
| | - Léa C Girard
- Department of Geosciences, University of Fribourg, Fribourg, Switzerland
| | - Ingmar Werneburg
- Fachbereich Geowissenschaften, Universität Tübingen, Tübingen, Germany
- Senckenberg Centre for Human Evolution and Palaeoenvironment, Tübingen, Germany
| | - Walter G Joyce
- Department of Geosciences, University of Fribourg, Fribourg, Switzerland
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2
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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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3
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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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Ponstein J, MacDougall MJ, Fröbisch J. A comprehensive phylogeny and revised taxonomy of Diadectomorpha with a discussion on the origin of tetrapod herbivory. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231566. [PMID: 39036512 PMCID: PMC11257076 DOI: 10.1098/rsos.231566] [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: 11/13/2023] [Revised: 03/23/2024] [Accepted: 04/08/2024] [Indexed: 07/23/2024]
Abstract
Among terrestrial tetrapods, the origin of herbivory marked a key evolutionary event that allowed for the evolution of modern terrestrial ecosystems. A 100 Ma gap separates the oldest terrestrial tetrapods and the first undisputed herbivorous tetrapods. While four clades of early tetrapod herbivores are undisputed amniotes, the phylogenetic position of Diadectomorpha with respect to Amniota has long been controversial. Given that the origin of herbivory coincides with the oldest amniotes, and obligate herbivory is unknown within amphibians, this suggests that a key adaptation necessary to evolve obligate herbivory is unique to amniotes. Historically, phylogenetic analyses have found Diadectomorpha as the sister-group to amniotes, but recent analyses recover Diadectomorpha as sister-group to Synapsida, within Amniota. We tested whether diadectomorphs are amniotes by updating the most recent character-taxon matrix. Specifically, we added new characters from the lower jaw and added diadectomorph taxa, resulting in a dataset of 341 characters and 61 operational taxonomic units. We updated the description of five diadectomorph jaws using microcomputed tomography data. Our majority-rule consensus places Diadectomorpha as sister-group to Synapsida; other methods do not recover this relationship. We revise diadectomorph taxonomy, erecting a new species from the early Permian Bromacker locality, Germany, and a new genus to accommodate 'Diadectes' sanmiguelensis.
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Affiliation(s)
- Jasper Ponstein
- Humboldt-Universität zu Berlin, Unter den Linden 6, 10117 Berlin, Germany
- Museum für Naturkunde Berlin, Invalidenstraße 43, 10115 Berlin, Germany
- Oertijdmuseum, Bosscheweg 80, 5283 WB Boxtel, The Netherlands
| | | | - Jörg Fröbisch
- Humboldt-Universität zu Berlin, Unter den Linden 6, 10117 Berlin, Germany
- Museum für Naturkunde Berlin, Invalidenstraße 43, 10115 Berlin, Germany
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5
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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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6
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Girard LC, Erickson JM, Lyson TR, Hoganson JW, Joyce WG. The cranial and postcranial morphology of Hutchemys rememdium and its impact on the phylogenetic relationships of Plastomenidae ( Testudinata, Trionychidae). SWISS JOURNAL OF PALAEONTOLOGY 2024; 143:22. [PMID: 38799181 PMCID: PMC11126460 DOI: 10.1186/s13358-024-00315-8] [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: 01/19/2024] [Accepted: 03/22/2024] [Indexed: 05/29/2024]
Abstract
Hutchemys rememdium is a poorly understood softshell turtle (Trionychidae) from the mid Paleocene of the Williston Basin of North America previously known only from postcranial remains. A particularly rich collection of previously undescribed material from the Tiffanian 4 North American Land Mammal Age (NALMA) of North Dakota is here presented consisting of numerous shells that document new variation, some non-shell postcrania, and cranial remains, which are described based on 3D models extracted from micro-CT data. Although the observed shell variation weakens previously noted differences with the younger species Hutchemys arctochelys from the Clarkforkian NALMA, the two taxa are still recognized as distinct. Parsimony and Bayesian phylogenetic analyses reaffirm the previously challenged placement of Hutchemys rememdium within the clade Plastomenidae, mostly based on novel observations of cranial characters made possible by the new material and the micro-CT data. The new topology supports the notion that the well-ossified plastron of plastomenids originated twice in parallel near the Cretaceous/Paleogene boundary, once in the Hutchemys lineage and once in the Gilmoremys/Plastomenus lineage. Hutchemys rememdium is notable for being the only documented species of trionychid in the mid Paleocene of the Williston Basin. The presence of multiple individuals in a carbonaceous claystone indicates this taxon lived in swamps and lakes and its expanded triturating surface suggests it had a durophagous diet. Supplementary Information The online version contains supplementary material available at 10.1186/s13358-024-00315-8.
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Affiliation(s)
- Léa C. Girard
- Department of Geosciences, University of Fribourg, 1700 Fribourg, Switzerland
| | - J. Mark Erickson
- Department of Geology, St. Lawrence University, Canton, NY 13617 USA
| | - Tyler R. Lyson
- Department of Earth Sciences, Denver Museum of Nature & Science, Denver, CO 80205 USA
| | | | - Walter G. Joyce
- Department of Geosciences, University of Fribourg, 1700 Fribourg, Switzerland
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7
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Evers SW, Al Iawati Z. Digital skull anatomy of the Oligocene North American tortoise Stylemys nebrascensis with taxonomic comments on the species and comparisons with extant testudinids of the Gopherus- Manouria clade. SWISS JOURNAL OF PALAEONTOLOGY 2024; 143:12. [PMID: 38455968 PMCID: PMC10914918 DOI: 10.1186/s13358-024-00311-y] [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: 11/22/2023] [Accepted: 02/12/2024] [Indexed: 03/09/2024]
Abstract
The anatomy of North American tortoises is poorly understood, despite a rich fossil record from the Eocene and younger strata. Stylemys nebrascensis is a particularly noteworthy turtle in this regard, as hundreds of specimens are known from Oligocene deposits, and as this species is one of the earliest fossil turtles to have been described in the scientific literature. Since its initial description based on a shell, many specimens with more complete material have been referred to Stylemys nebrascensis. Here, we review and confirm the referral of an important historic specimen to Stylemys nebrascensis, which includes shell, non-shell postcranial, and skull material. This allows us to document unique skull features of Stylemys nebrascensis (e.g., an unusual 'poststapedial canal' that connects the posterior skull surface with the cavum acustico-jugulare) and to refer another well-preserved skull to the species. Based on computed-tomography scanning of these two skulls, we provide a detailed description of the cranial and mandibular osteology of Stylemys nebrascensis. Stylemys nebrascensis has a combination of plesiomorphic skull characteristics (e.g., retention of a medial jugal process) and derived traits shared with extant gopher tortoises (e.g., median premaxillary ridge) that suggest it may be a stem-representative of the gopher tortoise lineage. This supports the hypothesis that extant and fossil tortoises from North America form a geographically restricted clade that split from Asian relatives during the Paleogene.
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Affiliation(s)
- Serjoscha W. Evers
- Department of Geosciences, University of Fribourg, Fribourg, Switzerland
| | - Zahra Al Iawati
- GeoZentrum Nordbayern, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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8
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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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9
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Gray JA, Gignac PM, Stanley EL. The first full body diffusible iodine-based contrast-enhanced computed tomography dataset and teaching materials for a member of the Testudines. Anat Rec (Hoboken) 2024; 307:535-548. [PMID: 37409685 DOI: 10.1002/ar.25282] [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: 05/11/2023] [Revised: 06/08/2023] [Accepted: 06/14/2023] [Indexed: 07/07/2023]
Abstract
Diffusible iodine-based contrast-enhanced Computed Tomography (diceCT) is now a widely used technique for imaging metazoan soft anatomy. Turtles present a particular challenge for anatomists; gross dissection is inherently destructive and irreversible, whereas their near complete shell of bony plates, covered with keratinous scutes, presents a barrier for iodine diffusion and significantly increases contrast-enhanced CT preparation time. Consequently, a complete dataset visualizing the internal soft anatomy of turtles at high resolution and in three dimensions has not yet been successfully achieved. Here we outline a novel method that augments traditional diceCT preparation with an iodine injection technique to acquire the first full body contrast-enhanced dataset for the Testudines. We show this approach to be an effective method of staining the soft tissues inside the shell. The resulting datasets were processed to produce anatomical 3D models that can be used in teaching and research. As diceCT becomes a widely employed method for nondestructively documenting the internal soft anatomy of alcohol preserved museum specimens, we hope that methods applicable to the more challenging of these, such as turtles, will contribute toward the growing stock of digital anatomy in online repositories.
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Affiliation(s)
- Jaimi A Gray
- Florida Museum of Natural History, Gainesville, Florida, USA
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10
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Spicher GE, Lyson TR, Evers SW. Updated cranial and mandibular description of the Late Cretaceous (Maastrichtian) baenid turtle Saxochelys gilberti based on micro-computed tomography scans and new information on the holotype-shell association. SWISS JOURNAL OF PALAEONTOLOGY 2024; 143:2. [PMID: 38274637 PMCID: PMC10805913 DOI: 10.1186/s13358-023-00301-6] [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: 10/14/2023] [Accepted: 12/08/2023] [Indexed: 01/27/2024]
Abstract
Saxochelys gilberti is a baenid turtle from the Late Cretaceous Hell Creek Formation of the United States of America known from cranial, shell, and other postcranial material. Baenid turtles are taxonomically diverse and common fossil elements within Late Cretaceous through Eocene faunas. Detailed anatomical knowledge is critical to understanding the systematics and morphological evolution of the group. This is particularly important as baenids represent an important group of continental vertebrates that survived the mass extinction event associated with the Cretaceous/Paleogene boundary. High-resolution micro-computed tomography scanning of the holotype skull reveals additional anatomical details for the already well-known Saxochelys gilberti. This includes the revision of some anatomical statements from the original description, but also detailed knowledge on internal anatomical features of the braincase and the description of a well-preserved axis (cervical vertebra 2). Our new detailed description and previous work on the shell and postcrania make Saxochelys one of the best-described, nearly complete baenid turtles, which are often only known from either isolated shell or cranial material. A revised phylogenetic analysis confirms the position of Saxochelys gilberti as a derived baenid (Eubaeninae) more closely related to Baena arenosa than to Eubaena cephalica. Supplementary Information The online version contains supplementary material available at 10.1186/s13358-023-00301-6.
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Affiliation(s)
- Gaël E. Spicher
- Departement of Geosciences, University of Fribourg, 1700 Fribourg, Switzerland
- Institute of Geosciences, Section Paleontology, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8, 53115 Bonn, Germany
| | - Tyler R. Lyson
- Department of Earth Sciences, Denver Museum of Nature & Science, Denver, CO USA
| | - Serjoscha W. Evers
- Departement of Geosciences, University of Fribourg, 1700 Fribourg, Switzerland
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11
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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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12
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Shipps BK, Peecook BR, Angielczyk KD. The topography of diet: Orientation patch count predicts diet in turtles. Anat Rec (Hoboken) 2022; 306:1214-1227. [PMID: 36458500 DOI: 10.1002/ar.25125] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 10/27/2022] [Accepted: 10/31/2022] [Indexed: 12/03/2022]
Abstract
Use of quantitative morphological methods in biology has increased with the availability of 3D digital data. Rotated orientation patch count (OPCr) leverages such data to quantify the complexity of an animal's feeding surface, and has previously been used to analyze how tooth complexity signals diet in squamates, crocodilians, and mammals. These studies show a strong correlation between dental complexity and diet. However, dietary prediction using this technique has not been tested on the feeding structures of edentulous (toothless) taxa. This study is the first to test the applicability of OPCr to the triturating surface morphology of a beaked clade. Fifty-five turtle specimens, 42 of which preserved both the skull and rhamphotheca, were categorized into dietary categories based on the food sources comprising 90% or 60% of their diets. Photogrammetric models of each specimen were read into molaR, producing OPCr results. Comparison of bone and rhamphotheca OPCr values shows no significant difference in complexity, implying that bone can suffice for predicting diet from morphology when keratin is absent. Carnivorous taxa have significantly lower OPCr values than herbivorous or omnivorous taxa, showing that feeding surface complexity in edentulous animals varies with diet similarly to tooth complexity in toothed taxa. Comparison of bone OPCr values by family shows that Testudinidae (tortoises) are more complex than Cheloniidae (sea turtles) and Chelydridae (snapping turtles), but that Cheloniidae and Chelydridae are not significantly different from each other. We therefore find that OPCr can be used to differentiate between carnivores and other dietary categories in edentulous taxa.
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Affiliation(s)
- Brenlee K. Shipps
- Department of Biological Sciences Idaho State University Pocatello Idaho USA
| | - Brandon R. Peecook
- Department of Biological Sciences Idaho State University Pocatello Idaho USA
- Idaho Museum of Natural History Idaho State University Pocatello Idaho USA
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