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Ristevski J, Weisbecker V, Scanlon JD, Price GJ, Salisbury SW. Cranial anatomy of the mekosuchine crocodylian Trilophosuchus rackhami Willis, 1993. Anat Rec (Hoboken) 2023; 306:239-297. [PMID: 36054424 PMCID: PMC10086963 DOI: 10.1002/ar.25050] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 01/25/2023]
Abstract
One of the best-preserved crocodylian fossil specimens from the Cenozoic of Australia is the holotype of the mekosuchine Trilophosuchus rackhami, from the middle Miocene (13.56 ± 0.67 Ma) Ringtail Site at Riversleigh, northwestern Queensland. Although lacking most of the snout, the holotype skull of T. rackhami (QMF16856) has an exceptionally well-preserved cranium. Micro-CT scanning of the holotype has allowed for all the preserved cranial bones to be digitally disarticulated, facilitating an unprecedented insight into the cranial anatomy of not just T. rackhami, but any mekosuchine. Trilophosuchus rackhami was a small-bodied crocodylian and one of the most morphologically distinct mekosuchines, characterized by a unique combination of cranial characteristics several of which are exclusive to the species. Fossil material that is definitively referrable to the species T. rackhami is currently known solely from the middle Miocene Ringtail Site. However, an isolated parietal from Hiatus Site at Riversleigh demonstrates that Trilophosuchus also occurred during the late Oligocene (~25 Ma), extending the range of the genus by more than 10 million years. The new description of T. rackhami also allowed for a reevaluation of its phylogenetic relationships. Our results reaffirm the placement of T. rackhami as a member of Mekosuchinae within the subclade Mekosuchini. In all analyses, Mekosuchinae was consistently found to be monophyletic and part of the larger crocodylian clade Longirostres. However, the assignment of Mekosuchinae as a subset of Crocodylidae is brought into question, suggesting that the status of Mekosuchinae as a subfamily should be reconsidered.
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Affiliation(s)
- Jorgo Ristevski
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Vera Weisbecker
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia.,College of Science and Engineering, Flinders University, Bedford Park, South Australia, Australia
| | - John D Scanlon
- Phoenix Environmental Sciences, Osborne Park, Western Australia, Australia
| | - Gilbert J Price
- School of Earth and Environmental Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Steven W Salisbury
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia
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Perrichon G, Hautier L, Pochat-Cottilloux Y, Raselli I, Salaviale C, Dailh B, Rinder N, Fernandez V, Adrien J, Lachambre J, Martin JE. Ontogenetic variability of the intertympanic sinus distinguishes lineages within Crocodylia. J Anat 2023; 242:1096-1123. [PMID: 36709416 PMCID: PMC10184552 DOI: 10.1111/joa.13830] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 01/10/2023] [Accepted: 01/10/2023] [Indexed: 01/30/2023] Open
Abstract
The phylogenetic relationships within crown Crocodylia remain contentious due to conflicts between molecular and morphological hypotheses. However, morphology-based datasets are mostly constructed on external characters, overlooking internal structures. Here, we use 3D geometric morphometrics to study the shape of the intertympanic sinus system in crown crocodylians during ontogeny, in order to assess its significance in a taxonomic context. Intertympanic sinus shape was found to be highly correlated with size and modulated by cranial shape during development. Still, adult sinus morphology distinguishes specimens at the family, genus and species level. We observe a clear distinction between Alligatoridae and Longirostres, a separation of different Crocodylus species and the subfossil Malagasy genus Voay, and a distinction between the Tomistoma and Gavialis lineages. Our approach is independent of molecular methods but concurs with the molecular topologies. Therefore, sinus characters could add significantly to morphological datasets, offering an alternative viewpoint to resolve problems in crocodylian relationships.
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Affiliation(s)
- Gwendal Perrichon
- CNRS UMR 5276, Université Claude Bernard Lyon 1, ENS de Lyon, Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, Villeurbanne, France
| | - Lionel Hautier
- Institut des Sciences de l'Évolution, Université Montpellier, CNRS, IRD, EPHE, Montpellier, France.,Mammal Section, Life Sciences, Vertebrate Division, The Natural History Museum, London, UK
| | - Yohan Pochat-Cottilloux
- CNRS UMR 5276, Université Claude Bernard Lyon 1, ENS de Lyon, Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, Villeurbanne, France
| | - Irena Raselli
- Geoscience Department, Chemin de Musée 6, University of Fribourg, Jurassica Museum, Porrentruy, Switzerland
| | - Céline Salaviale
- CNRS UMR 5276, Université Claude Bernard Lyon 1, ENS de Lyon, Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, Villeurbanne, France
| | - Benjamin Dailh
- CNRS UMR 5276, Université Claude Bernard Lyon 1, ENS de Lyon, Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, Villeurbanne, France
| | - Nicolas Rinder
- CNRS UMR 5276, Université Claude Bernard Lyon 1, ENS de Lyon, Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, Villeurbanne, France
| | | | - Jérôme Adrien
- Laboratoire Matériaux, Ingénierie et Science, Institut National des Sciences Appliquées de Lyon, Villeurbanne, France
| | - Joël Lachambre
- Laboratoire Matériaux, Ingénierie et Science, Institut National des Sciences Appliquées de Lyon, Villeurbanne, France
| | - Jeremy E Martin
- CNRS UMR 5276, Université Claude Bernard Lyon 1, ENS de Lyon, Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, Villeurbanne, France
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Holliday CM, Schachner ER. Dispatches from the age of crocodiles: New discoveries from ancient lineages. Anat Rec (Hoboken) 2022; 305:2343-2352. [PMID: 35912969 DOI: 10.1002/ar.25043] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/09/2022] [Accepted: 07/11/2022] [Indexed: 01/19/2023]
Abstract
Crocodilians inspire researchers and the public alike with their explosive hunting methodologies, distinct craniofacial and dental morphology, and resplendent fossil record. This special issue highlights recent advances in the biology and paleontology of this fascinating lineage of vertebrates. The authors in this volume bring crocodylians and their extinct ancestors to life using a variety of approaches including fieldwork, imaging, 3D modeling, developmental biology, physiological monitoring, dissection, and a host of other comparative methods. Our journey begins with early crocodylomorphs from the Triassic, carries us through the radiation of crocodyliforms during the rest of the Mesozoic Era, and finally celebrates the diversification development and biology of extant crocodylians. Crocodyliform science has grown appreciably the past few decades. New fossil species and genetic evidence continue to keep phylogenies and our understanding of relationships wavering in key places of the tree such as the relationships of the extinct marine thalattosuchians as well as still living species like gharials. The application of imaging approaches and 3D modeling to both preserved tissues as well as living specimens is now revealing patterns in brain and lung evolution and function, growth strategies, and feeding and locomotor behaviors across the lineage. Comparative anatomical studies are offering new data on genitals, cephalic venous drainage and thoracoabdominal pressures. The new discoveries found here only reveal there is far more work to be done to understand the biology and behavior responsible for the great radiation extinct suchians and their crocodylian descendants experienced during their conquest of Mesozoic and Tertiary ecosystems.
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Affiliation(s)
- Casey M Holliday
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | - Emma R Schachner
- Department of Cell Biology and Anatomy, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
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