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Miedema F, Bastiaans D, Scheyer TM, Klug C, Maxwell EE. A large new Middle Jurassic ichthyosaur shows the importance of body size evolution in the origin of the Ophthalmosauria. BMC Ecol Evol 2024; 24:34. [PMID: 38493100 PMCID: PMC10944604 DOI: 10.1186/s12862-024-02208-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Accepted: 01/29/2024] [Indexed: 03/18/2024] Open
Abstract
The Middle Jurassic is an important time period for the evolutionary history of marine reptiles as it represented a transitional phase for many clades. Notably, in ichthyosaurs, many early parvipelvian taxa went extinct. The Middle Jurassic saw the emergence of the derived Ophthalmosauria, ultimately becoming the dominant ichthyosaurian clade by the end of the epoch. Even though this is an important period in the evolutionary history of Ophthalmosauria, our understanding remains limited in terms of morphology and taxonomy due to the scarcity of vertebrate-bearing strata. Here we present a large new ichthyosaur from the Bajocian of Switzerland, represented by an almost complete skull with 3D-preserved bones, the (inter)clavicles and a large portion of the postcranial skeleton. After CT- and surface scanning, we reconstructed the 3D in vivo morphology. Our morphological observations and phylogenetic analyses show that the new taxon named Argovisaurus martafernandezi is nested at the base of the Ophthalmosauria. The holotype and only known specimen of Argovisaurus likely represents an adult individual. Bajocian members of the Ophthalmosauria (Mollesaurus and Argovisaurus) were large-bodied animals, a trait typically associated with the more derived Platypterygiinae. This hints at the importance of a large body size early in ophthalmosaurian evolution.LSID: urn:lsid:zoobank.org:act:C3312628-1544-4B87-BBE3-B12346A30BE3LSID: urn:lsid:zoobank.org:act:23C2BD71-8CF0-4D99-848A-0D631518415B.
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Affiliation(s)
- Feiko Miedema
- Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, Stuttgart, 70191, Germany.
- Universität Zürich, Paläontologisches Institut, Karl Schmid-Strasse 4, Zürich, 8006, Switzerland.
| | - Dylan Bastiaans
- Universität Zürich, Paläontologisches Institut, Karl Schmid-Strasse 4, Zürich, 8006, Switzerland
- NHMB: Naturhistorisches Museum Basel, Augustinergasse 2, Basel, 4001, Switzerland
| | - Torsten M Scheyer
- Universität Zürich, Paläontologisches Institut, Karl Schmid-Strasse 4, Zürich, 8006, Switzerland
| | - Christian Klug
- Universität Zürich, Paläontologisches Institut, Karl Schmid-Strasse 4, Zürich, 8006, Switzerland
| | - Erin E Maxwell
- Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, Stuttgart, 70191, Germany
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Bastiaans D, Buffa V, Scheyer TM. To glide or to swim? A reinvestigation of the enigmatic Wapitisaurus problematicus (Reptilia) from the Early Triassic of British Columbia, Canada. ROYAL SOCIETY OPEN SCIENCE 2023; 10:231171. [PMID: 38026014 PMCID: PMC10646446 DOI: 10.1098/rsos.231171] [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: 09/06/2023] [Accepted: 10/20/2023] [Indexed: 12/01/2023]
Abstract
Wapitisaurus problematicus was initially described as a member of the Weigeltisauridae, a clade of Late Permian gliding reptiles from Eurasia and Madagascar. However, the poor preservation of the holotype and only known specimen, from the lower Sulphur Mountain Formation at Ganoid Ridge (British Columbia, Canada), raised doubts about this assignment. Here, we redescribe W. problematicus and reassess its systematic position among diapsid reptiles. Comparison with all known weigeltisaurids, as well as contemporaneous reptiles from the Sulphur Mountain Formation, indicates that the taxon instead represents a thalattosauroid thalattosauriform, with noted similarities to Thalattosaurus and Paralonectes. This reidentification restricts weigeltisaurids to the Late Permian, with no occurrence in North America. Wapitisaurus problematicus potentially represents one of the oldest thalattosauriforms and increases our understanding of their diversity and disparity during the late Early and Middle Triassic. The close morphological similarities with later (thalattosauroid) thalattosauriforms and their high abundance in (shallow) marine settings may indicate an earlier invasion of this realm than previously assumed. This parallels observations in early ichthyopterygians with widespread opportunistic trophic niche diversification occurring relatively rapidly after the end-Permian mass extinction event.
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Affiliation(s)
- Dylan Bastiaans
- Palaeontological Institute and Museum, University of Zurich, Zurich 8006, Switzerland
| | - Valentin Buffa
- Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Johannesburg, Gauteng WITS 2050, South Africa
- Muséum National d'Histoire Naturelle, Centre de Recherche en Paléontologie – Paris, UMR 7207 CNRS-MNHN-SU, CP38, 8 Rue Buffon, Paris, Île-de-France 75005, France
| | - Torsten M. Scheyer
- Palaeontological Institute and Museum, University of Zurich, Zurich 8006, Switzerland
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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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Abumandour MMA, Morsy K, Abumandour R, El-Bakary N, Rashwan A, Elghoul M. Scanning electron microscopic and histological features of the oral cavity of the Egyptian tortoise (Testudo kleinmanni). Anat Histol Embryol 2023; 52:204-214. [PMID: 36204990 DOI: 10.1111/ahe.12872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 09/01/2022] [Accepted: 09/23/2022] [Indexed: 11/27/2022]
Abstract
This investigation was led to depict the structural and functional adaptations of the oral cavity of herbivorous Egyptian tortoises using scanning electron and light microscopes. The SEM showed that the triangular papillary tongue possessed three conical papillary subtypes: the rectangular conical on the tip, the round conical on the rest of the dorsal lingual surface and the elongated conical on the caudal portion of the lingual wing. The presence of the serrated lips with their valves compensated for the absence of the teeth. The rostral part had a vomeronasal opening while the middle part had the choana, but the caudal part had numerous openings of the salivary glands. There are three palatine folds: a single median palatine fold, two peripheral palatine folds and the choanal fold. The current histological results show the keratinized dorsal lingual surface, in which the keratinized layer extended to cover the papillae. Two types of lingual glands, according to their position, are papillary superficial and deep lingual glands. Papillary or superficial glands open in the interpapillary spaces via narrow openings, while the deep glands are surrounded by well-developed muscles and open via wide openings on the dorsal lingual surface. An entoglossal cartilaginous structure of hyaline cartilage was found in the mid- and hindtongue, with numerous chondrocytes lodged within the lacunae. Our results conclude that the oral cavity of the herbivorous Egyptian tortoise was adapted to the dietary and vigorous demands of the Egyptian fauna.
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Affiliation(s)
- Mohamed M A Abumandour
- Anatomy and EmbryologyDepartment, Faculty of Veterinary Medicine, Alexandria University, Egypt
| | - Kareem Morsy
- Biology Department, College of Science, King Khalid University, Abha, Saudi Arabia.,Zoology Department, Faculty of Science, Cairo University, Cairo, Egypt
| | - Ramzy Abumandour
- Department of Basic Engineering Science, Faculty of Engineering, Menoufia University, Shebin El-Kom, Egypt
| | - Neveen El-Bakary
- Department of Zoology, Faculty of Science, Damietta University, Egypt
| | - Ahmed Rashwan
- Department of Anatomy and Embryology, Faculty of Veterinary Medicine, Damanhour University, Egypt.,Department of Life Science Frontiers, Center for iPS Cell Research and Application, Kyoto University, Japan
| | - Mahmoud Elghoul
- Department of Histology and Cytology, Faculty of Veterinary Medicine, Alexandria University, Egypt
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Miedema F, Maxwell EE. Ontogenetic variation in the skull of Stenopterygius quadriscissus with an emphasis on prenatal development. Sci Rep 2022; 12:1707. [PMID: 35105895 PMCID: PMC8807662 DOI: 10.1038/s41598-022-05540-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 12/16/2021] [Indexed: 12/03/2022] Open
Abstract
The availability of a large sample size from a range of ontogenetic stages makes Stenopterygius quadriscissus a good model to study ontogenetic variation in a fossil sauropsid. We qualitatively examined pre- and postnatal ontogenetic changes in the cranium of S. quadriscissus. The prenatal ossification sequence is similar to other diapsids, exhibiting delayed chondrocranial ossification compared to the dermatocranium. In the dermatocranium, the circumorbital area is more ossified earlier in development relative to other elements, especially those of the skull roof where ossification is comparatively weaker across prenatal stages. Perinatally all cranial elements are ossified, and many scarf and step joints are already closed. We propose four prenatal and three postnatal stages in S. quadriscissus on the basis of relative ossification, size and qualitative cranial characters pertaining to the jugal, parietal, frontal, pterygoid and surangular. These will provide a basis for determining ontogenetic stages in other ichthyosaurs. Moreover, our postnatal observations aid in refining ontogenetic characters for phylogenetic studies. Lastly, we observed that the antimeric sutures of the midline of the skull roof are open perinatally and that fusion of the midline only appears in the adult stage. We hypothesize that the loose connection of the midline functions as a fontanelle, limiting potential damage during birth.
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Affiliation(s)
- Feiko Miedema
- Staatliches Museum Für Naturkunde Stuttgart, Rosenstein 1, 70191, Stuttgart, Germany.
- Department of Paleontology, Hohenheim University, Schloss Hohenheim 1 A, 70599, Stuttgart, Germany.
| | - Erin E Maxwell
- Staatliches Museum Für Naturkunde Stuttgart, Rosenstein 1, 70191, Stuttgart, Germany
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