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Dos Santos DM, de Carvalho JC, de Oliveira CEM, de Andrade MB, Santucci RM. Cranial and postcranial anatomy of a juvenile baurusuchid (Notosuchia, Crocodylomorpha) and the taxonomical implications of ontogeny. Anat Rec (Hoboken) 2024. [PMID: 38429867 DOI: 10.1002/ar.25419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 02/16/2024] [Accepted: 02/19/2024] [Indexed: 03/03/2024]
Abstract
Baurusuchidae comprises a clade of top-tier terrestrial predators and are among the most abundant crocodyliforms found in the Adamantina Formation, Bauru Basin, Brazil (Campanian-Maastrichtian). Here, we provide a detailed description of the cranial and postcranial osteology and myology of the most complete juvenile baurusuchid found to date. Although the preservation of juvenile individuals is somewhat rare, previously reported occurrences of baurusuchid egg clutches, a yearling individual, and larger, but skeletally immature specimens, comprise a unique opportunity to track anatomical changes throughout their ontogenetic series. Its cranial anatomy was resolved with the aid of a three-dimensional model generated by the acquisition of computed tomography data, and its inferred adductor mandibular musculature was compared to that of mature specimens in order to assess possible ontogenetic shifts. A subsequent phylogenetic analysis included the scoring of Gondwanasuchus scabrosus, the smallest baurusuchid species known to date, to evaluate its phylogenetic relations relative to a known juvenile. We find considerable differences between juveniles and adults concerning skull ornamentation and muscle development, which might indicate ontogenetic niche partitioning, and also anatomical and phylogenetic evidence that G. scabrosus corresponds to a young semaphoront lacking mature cranial features.
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Affiliation(s)
- Daniel Martins Dos Santos
- Zoology Graduate Program, Institute of Biological Sciences, University of Brasília, Brasília, Brazil
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Lessner EJ, Dollman KN, Clark JM, Xu X, Holliday CM. Ecomorphological patterns in trigeminal canal branching among sauropsids reveal sensory shift in suchians. J Anat 2023; 242:927-952. [PMID: 36680380 PMCID: PMC10093182 DOI: 10.1111/joa.13826] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 01/03/2023] [Accepted: 01/03/2023] [Indexed: 01/22/2023] Open
Abstract
The vertebrate trigeminal nerve is the primary mediator of somatosensory information from nerve endings across the face, extending nerve branches through bony canals in the face and mandibles, terminating in sensory receptors. Reptiles evolved several extreme forms of cranial somatosensation in which enhanced trigeminal tissues are present in species engaging in unique mechanosensory behaviors. However, morphology varies by clade and ecology among reptiles. Few lineages approach the extreme degree of tactile somatosensation possessed by crocodylians, the only remaining members of a clade that underwent an ecological transition from the terrestrial to semiaquatic habitat, also evolving a specialized trigeminal system. It remains to be understood how trigeminal osteological correlates inform how adaptations for enhanced cranial sensation evolved in crocodylians. Here we identify an increase in sensory abilities in Early Jurassic crocodylomorphs, preceding the transitions to a semiaquatic habitat. Through quantification of trigeminal neurovascular canal branching patterns in an extant phylogenetic bracket we quantify and identify morphologies associated with sensory behaviors in representative fossil taxa, we find stepwise progression of increasing neurovascular canal density, complexity, and distribution from the primitive archosaurian to the derived crocodilian condition. Model-based inferences of sensory ecologies tested on quantified morphologies of extant taxa with known sensory behaviors indicate a parallel increase in sensory abilities among pseudosuchians. These findings establish patterns of reptile trigeminal ecomorphology, revealing evolutionary patterns of somatosensory ecology.
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Affiliation(s)
- Emily J Lessner
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | | | - James M Clark
- Department of Biological Sciences, George Washington University, Washington, District of Columbia, USA
| | - Xing Xu
- Centre for Vertebrate Evolutionary Biology, Yunnan University, Kunming, China.,Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Casey M Holliday
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
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Cuff AR, Wiseman ALA, Bishop PJ, Michel KB, Gaignet R, Hutchinson JR. Anatomically grounded estimation of hindlimb muscle sizes in Archosauria. J Anat 2022; 242:289-311. [PMID: 36206401 PMCID: PMC9877486 DOI: 10.1111/joa.13767] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/26/2022] [Accepted: 08/31/2022] [Indexed: 02/01/2023] Open
Abstract
In vertebrates, active movement is driven by muscle forces acting on bones, either directly or through tendinous insertions. There has been much debate over how muscle size and force are reflected by the muscular attachment areas (AAs). Here we investigate the relationship between the physiological cross-sectional area (PCSA), a proxy for the force production of the muscle, and the AA of hindlimb muscles in Nile crocodiles and five bird species. The limbs were held in a fixed position whilst blunt dissection was carried out to isolate the individual muscles. AAs were digitised using a point digitiser, before the muscle was removed from the bone. Muscles were then further dissected and fibre architecture was measured, and PCSA calculated. The raw measures, as well as the ratio of PCSA to AA, were studied and compared for intra-observer error as well as intra- and interspecies differences. We found large variations in the ratio between AAs and PCSA both within and across species, but muscle fascicle lengths are conserved within individual species, whether this was Nile crocodiles or tinamou. Whilst a discriminant analysis was able to separate crocodylian and avian muscle data, the ratios for AA to cross-sectional area for all species and most muscles can be represented by a single equation. The remaining muscles have specific equations to represent their scaling, but equations often have a relatively high success at predicting the ratio of muscle AA to PCSA. We then digitised the muscle AAs of Coelophysis bauri, a dinosaur, to estimate the PCSAs and therefore maximal isometric muscle forces. The results are somewhat consistent with other methods for estimating force production, and suggest that, at least for some archosaurian muscles, that it is possible to use muscle AA to estimate muscle sizes. This method is complementary to other methods such as digital volumetric modelling.
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Affiliation(s)
- Andrew R. Cuff
- Structure and Motion Laboratory, Department of Comparative Biomedical SciencesRoyal Veterinary CollegeHatfieldUK,Human Anatomy Resource CentreUniversity of LiverpoolLiverpoolUK
| | - Ashleigh L. A. Wiseman
- Structure and Motion Laboratory, Department of Comparative Biomedical SciencesRoyal Veterinary CollegeHatfieldUK
| | - Peter J. Bishop
- Structure and Motion Laboratory, Department of Comparative Biomedical SciencesRoyal Veterinary CollegeHatfieldUK,Museum of Comparative Zoology and Department of Organismic and Evolutionary BiologyHarvard UniversityCambridgeUSA,Geosciences ProgramQueensland MuseumBrisbaneQueenslandAustralia
| | - Krijn B. Michel
- Structure and Motion Laboratory, Department of Comparative Biomedical SciencesRoyal Veterinary CollegeHatfieldUK
| | - Raphäelle Gaignet
- Structure and Motion Laboratory, Department of Comparative Biomedical SciencesRoyal Veterinary CollegeHatfieldUK
| | - John R. Hutchinson
- Structure and Motion Laboratory, Department of Comparative Biomedical SciencesRoyal Veterinary CollegeHatfieldUK
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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: 1] [Impact Index Per Article: 0.5] [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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Laitman JT, Smith HF. Teeth to the right of me, teeth to the left of me, teeth in front of me -hello to the world of crocodiles and their many relatives in a new special issue of The Anatomical Record. Anat Rec (Hoboken) 2022; 305:2337-2342. [PMID: 35906076 DOI: 10.1002/ar.25046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 07/12/2022] [Indexed: 11/10/2022]
Affiliation(s)
- Jeffrey T Laitman
- The Anatomical Record, Center for Anatomy and Functional Morphology, Icahn School of Medicine, Mount Sinai, New York, USA
| | - Heather F Smith
- The Anatomical Record, Center for Anatomy and Functional Morphology, Icahn School of Medicine, Mount Sinai, New York, USA
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Holliday CM, Sellers KC, Lessner EJ, Middleton KM, Cranor C, Verhulst CD, Lautenschlager S, Bader K, Brown MA, Colbert MW. New frontiers in imaging, anatomy, and mechanics of crocodylian jaw muscles. Anat Rec (Hoboken) 2022; 305:3016-3030. [PMID: 35723491 DOI: 10.1002/ar.25011] [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: 03/02/2022] [Revised: 05/16/2022] [Accepted: 05/21/2022] [Indexed: 12/12/2022]
Abstract
New imaging and biomechanical approaches have heralded a renaissance in our understanding of crocodylian anatomy. Here, we review a series of approaches in the preparation, imaging, and functional analysis of the jaw muscles of crocodylians. Iodine-contrast microCT approaches are enabling new insights into the anatomy of muscles, nerves, and other soft tissues of embryonic as well as adult specimens of alligators. These imaging data and other muscle modeling methods offer increased accuracy of muscle sizes and attachments without destructive methods like dissection. 3D modeling approaches and imaging data together now enable us to see and reconstruct 3D muscle architecture which then allows us to estimate 3D muscle resultants, but also measurements of pennation in ways not seen before. These methods have already revealed new information on the ontogeny, diversity, and function of jaw muscles and the heads of alligators and other crocodylians. Such approaches will lead to enhanced and accurate analyses of form, function, and evolution of crocodylians, their fossil ancestors and vertebrates in general.
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Affiliation(s)
- Casey M Holliday
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | - Kaleb C Sellers
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | - Emily J Lessner
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | - Kevin M Middleton
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | - Corrine Cranor
- Department of Geology and Geologic Engineering, South Dakota School of Mines and Technology, Rapid City, South Dakota, USA
| | - Conner D Verhulst
- Department of Pathology and Anatomical Sciences, University of Missouri, Columbia, Missouri, USA
| | - Stephan Lautenschlager
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK
| | - Kenneth Bader
- Texas Vertebrate Paleontology Collection, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA
| | - Matthew A Brown
- Texas Vertebrate Paleontology Collection, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA
| | - Matthew W Colbert
- Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA
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