dr Yohan Pochat-Cottilloux
Scientific interests
- Paleobiology, phylogeny and evolution of crocodylomorphs and reptiles throughout the Mesozoic and the Cenozoic
- Study of form and function of endocranial structures
- Geochemistry as a proxy for the way organisms lived
Research projects
ongoing projects
- New Miocene land vertebrates from the northwestern Paratethys shores and their implications for Eurasian faunal exchange (postdoctoral researcher, NCN OPUS-24)
previous projects
- Origin and evolution of terrestriality in altirostral forms of crocodylomorphs (PhD student, Université Claude Bernard Lyon 1 & CNRS, ANR SEBEK grant)
Publications
2024
Pochat-Cottilloux, Yohan
A review of the non-semiaquatic adaptations of extinct crocodylomorphs throughout their fossil record Journal Article
In: The Anatomical Record, vol. n/a, no. n/a, 2024.
@article{https://doi.org/10.1002/ar.25586,
title = {A review of the non-semiaquatic adaptations of extinct crocodylomorphs throughout their fossil record},
author = {Yohan Pochat-Cottilloux},
url = {https://anatomypubs.onlinelibrary.wiley.com/doi/abs/10.1002/ar.25586},
doi = {https://doi.org/10.1002/ar.25586},
year = {2024},
date = {2024-11-25},
journal = {The Anatomical Record},
volume = {n/a},
number = {n/a},
abstract = {Abstract Crocodylomorphs constitute a clade of archosaurs that have thrived since the Mesozoic until today and have survived numerous major biological crises. Contrary to historic belief, their semiaquatic extant representatives (crocodylians) are not living fossils, and, during their evolutionary history, crocodylomorphs have evolved to live in a variety of environments. This review aims to summarize the non-semiaquatic adaptations (i.e., either terrestrial or fully aquatic) of different groups from different periods, highlighting how exactly those different lifestyles are inferred for those animals, with regard to their geographic and temporal distribution and phylogenetic relationships. The ancestral condition for Crocodylomorpha seems to have been a terrestrial lifestyle, linked with several morphological adaptations such as an altirostral skull, long limbs allowing a fully erect posture and a specialized dentition for diets based on land. However, some members of this clade, such as thalattosuchians and dyrosaurids display adaptations for an opposite, aquatic lifestyle, interestingly inferred from the same type of morphological observations. Finally, new techniques for inferring the paleobiology of those extinct animals have been put forward in the last decade, appearing as a complementary approach to traditional morphological descriptions and comparisons. Such is the case of paleoneuroanatomical (CT scan data), histological, and geochemical studies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Crocodylomorphs constitute a clade of archosaurs that have thrived since the Mesozoic until today and have survived numerous major biological crises. Contrary to historic belief, their semiaquatic extant representatives (crocodylians) are not living fossils, and, during their evolutionary history, crocodylomorphs have evolved to live in a variety of environments. This review aims to summarize the non-semiaquatic adaptations (i.e., either terrestrial or fully aquatic) of different groups from different periods, highlighting how exactly those different lifestyles are inferred for those animals, with regard to their geographic and temporal distribution and phylogenetic relationships. The ancestral condition for Crocodylomorpha seems to have been a terrestrial lifestyle, linked with several morphological adaptations such as an altirostral skull, long limbs allowing a fully erect posture and a specialized dentition for diets based on land. However, some members of this clade, such as thalattosuchians and dyrosaurids display adaptations for an opposite, aquatic lifestyle, interestingly inferred from the same type of morphological observations. Finally, new techniques for inferring the paleobiology of those extinct animals have been put forward in the last decade, appearing as a complementary approach to traditional morphological descriptions and comparisons. Such is the case of paleoneuroanatomical (CT scan data), histological, and geochemical studies.
Conedera, Davide; Pochat-Cottilloux, Yohan; Rinder, Nicolas; Adrien, Jérôme; Martin, Jeremy E.
In: Journal of Vertebrate Paleontology, vol. 43, no. 4, pp. e2313612, 2024.
@article{doi:10.1080/02724634.2024.2313612,
title = {An anatomical reappraisal of the dwarf crocodylian Arambourgia gaudryi from the Eocene of Quercy (France) using CT data and its implications for the phylogeny and paleoecology of basally branching alligatoroids},
author = {Davide Conedera and Yohan Pochat-Cottilloux and Nicolas Rinder and Jérôme Adrien and Jeremy E. Martin},
url = {https://doi.org/10.1080/02724634.2024.2313612},
doi = {10.1080/02724634.2024.2313612},
year = {2024},
date = {2024-03-26},
urldate = {2024-03-26},
journal = {Journal of Vertebrate Paleontology},
volume = {43},
number = {4},
pages = {e2313612},
publisher = {Taylor & Francis},
abstract = {After about a century, the skull of the holotype and sole specimen of Arambourgia gaudryi from the Eocene of Quercy (France) is here redescribed. Its interest resides in its extreme morphology, such as its very small skull and altirostral condition, that raises questions about its maturity, taxonomic validity, and paleoecology. In order to reveal previously hidden anatomical details, we used computed microtomography (µCT-scan) data to digitally extract the bones of the cranium and mandible, as well as the endocranial structures. Here, we update the osteological description of A. gaudryi, outlining new characters and re-evaluating anatomical details. Comparing it with ontogenetic series of extant crocodylians, we confirm that the specimen is a mature individual of a dwarf species with pedomorphic features. Our phylogenetic analyses indicate that A. gaudryi is an alligatorine. Comparisons with other small alligatoroid taxa show that it is indeed a valid species. The depositional environment of the finding site suggests a continental context with a karstic network. Taking this into account, together with its peculiar anatomy, we propose that A. gaudryi was a semi-terrestrial animal occupying an ecological niche similar to that of extant juvenile or dwarf crocodylians. Finally, we discuss the current knowledge of the paleobiogeography of Alligatoroidea in Europe during the Paleogene. Arambourgia gaudryi was likely part of a group of small early globidontans that arrived in the Old World, probably from North America, around the end of the Paleocene and that dispersed to at least four localities of the ancient European archipelago.},
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}
After about a century, the skull of the holotype and sole specimen of Arambourgia gaudryi from the Eocene of Quercy (France) is here redescribed. Its interest resides in its extreme morphology, such as its very small skull and altirostral condition, that raises questions about its maturity, taxonomic validity, and paleoecology. In order to reveal previously hidden anatomical details, we used computed microtomography (µCT-scan) data to digitally extract the bones of the cranium and mandible, as well as the endocranial structures. Here, we update the osteological description of A. gaudryi, outlining new characters and re-evaluating anatomical details. Comparing it with ontogenetic series of extant crocodylians, we confirm that the specimen is a mature individual of a dwarf species with pedomorphic features. Our phylogenetic analyses indicate that A. gaudryi is an alligatorine. Comparisons with other small alligatoroid taxa show that it is indeed a valid species. The depositional environment of the finding site suggests a continental context with a karstic network. Taking this into account, together with its peculiar anatomy, we propose that A. gaudryi was a semi-terrestrial animal occupying an ecological niche similar to that of extant juvenile or dwarf crocodylians. Finally, we discuss the current knowledge of the paleobiogeography of Alligatoroidea in Europe during the Paleogene. Arambourgia gaudryi was likely part of a group of small early globidontans that arrived in the Old World, probably from North America, around the end of the Paleocene and that dispersed to at least four localities of the ancient European archipelago.
Pochat-Cottilloux, Yohan; Lachambre, Joël; Amiot, Romain; Martin, Jeremy E.
CT scan data for the original holotype of Hamadasuchus rebouli Buffetaut 1994 Journal Article
In: MorphoMuseuM, vol. 10, no. 1, pp. e222, 2024, ISSN: 2274-0422.
@article{PochatCottilloux2024,
title = {CT scan data for the original holotype of Hamadasuchus rebouli Buffetaut 1994},
author = {Yohan Pochat-Cottilloux and Joël Lachambre and Romain Amiot and Jeremy E. Martin},
url = {http://dx.doi.org/10.18563/journal.m3.222},
doi = {10.18563/journal.m3.222},
issn = {2274-0422},
year = {2024},
date = {2024-02-06},
urldate = {2024-02-01},
journal = {MorphoMuseuM},
volume = {10},
number = {1},
pages = {e222},
publisher = {Centre National de la Recherche Scientifique - Institut des Sciences de l’Evolution de Montpellier UMR 5554},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Pochat-Cottilloux, Yohan; Lauprasert, Komsorn; Chanthasit, Phornphen; Manitkoon, Sita; Adrien, Jérôme; Lachambre, Joël; Amiot, Romain; Martin, Jeremy E
New Cretaceous neosuchians (Crocodylomorpha) from Thailand bridge the evolutionary history of atoposaurids and paralligatorids Journal Article
In: 2024, ISSN: 1096-3642.
@article{Pochat-Cottilloux2024,
title = {New Cretaceous neosuchians (Crocodylomorpha) from Thailand bridge the evolutionary history of atoposaurids and paralligatorids},
author = {Yohan Pochat-Cottilloux and Komsorn Lauprasert and Phornphen Chanthasit and Sita Manitkoon and Jérôme Adrien and Joël Lachambre and Romain Amiot and Jeremy E Martin},
doi = {10.1093/zoolinnean/zlad195},
issn = {1096-3642},
year = {2024},
date = {2024-01-09},
urldate = {2024-01-09},
publisher = {Oxford University Press (OUP)},
abstract = {<jats:title>Abstract</jats:title>
<jats:p>The origin of modern crocodylians is rooted in the Cretaceous, but their evolutionary history is obscure because the relationships of outgroups and transitional forms are poorly resolved. Here, we describe a new form, Varanosuchus sakonnakhonensis gen. nov., sp. nov., from the Early Cretaceous of Thailand that fills an evolutionary gap between Paralligatoridae and Atoposauridae, two derived neosuchian lineages with previously unsettled phylogenetic relationships. Three individuals, including a complete skull and associated postcranial remains, allow for a detailed description and phylogenetic analysis. The new taxon is distinguished from all other crocodylomorphs by an association of features, including a narrow altirostral morphology, a dorsal part of the postorbital with an anterolaterally facing edge, a depression on the posterolateral surface of the maxilla, and fully pterygoid-bound choanae. A phylogenetic analysis confirms the monophyly and taxonomic content of Atoposauridae and Paralligatoridae, and we underline the difficulty in reaching a robust definition of Eusuchia. Furthermore, we put forward further arguments related to the putative terrestrial ecology with semi-aquatic affinities of atoposaurids based on their altirostral snout morphology and osteoderm ornamentation.</jats:p>},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
<jats:title>Abstract</jats:title>
<jats:p>The origin of modern crocodylians is rooted in the Cretaceous, but their evolutionary history is obscure because the relationships of outgroups and transitional forms are poorly resolved. Here, we describe a new form, Varanosuchus sakonnakhonensis gen. nov., sp. nov., from the Early Cretaceous of Thailand that fills an evolutionary gap between Paralligatoridae and Atoposauridae, two derived neosuchian lineages with previously unsettled phylogenetic relationships. Three individuals, including a complete skull and associated postcranial remains, allow for a detailed description and phylogenetic analysis. The new taxon is distinguished from all other crocodylomorphs by an association of features, including a narrow altirostral morphology, a dorsal part of the postorbital with an anterolaterally facing edge, a depression on the posterolateral surface of the maxilla, and fully pterygoid-bound choanae. A phylogenetic analysis confirms the monophyly and taxonomic content of Atoposauridae and Paralligatoridae, and we underline the difficulty in reaching a robust definition of Eusuchia. Furthermore, we put forward further arguments related to the putative terrestrial ecology with semi-aquatic affinities of atoposaurids based on their altirostral snout morphology and osteoderm ornamentation.</jats:p>
<jats:p>The origin of modern crocodylians is rooted in the Cretaceous, but their evolutionary history is obscure because the relationships of outgroups and transitional forms are poorly resolved. Here, we describe a new form, Varanosuchus sakonnakhonensis gen. nov., sp. nov., from the Early Cretaceous of Thailand that fills an evolutionary gap between Paralligatoridae and Atoposauridae, two derived neosuchian lineages with previously unsettled phylogenetic relationships. Three individuals, including a complete skull and associated postcranial remains, allow for a detailed description and phylogenetic analysis. The new taxon is distinguished from all other crocodylomorphs by an association of features, including a narrow altirostral morphology, a dorsal part of the postorbital with an anterolaterally facing edge, a depression on the posterolateral surface of the maxilla, and fully pterygoid-bound choanae. A phylogenetic analysis confirms the monophyly and taxonomic content of Atoposauridae and Paralligatoridae, and we underline the difficulty in reaching a robust definition of Eusuchia. Furthermore, we put forward further arguments related to the putative terrestrial ecology with semi-aquatic affinities of atoposaurids based on their altirostral snout morphology and osteoderm ornamentation.</jats:p>
2023
Perrichon, Gwendal; Pochat-Cottilloux, Yohan; Conedera, Davide; Richardin, Pascale; Fernandez, Vincent; Hautier, Lionel; Martin, Jeremy E.
In: The Anatomical Record, vol. n/a, no. n/a, 2023.
@article{https://doi.org/10.1002/ar.25367,
title = {Neuroanatomy and pneumaticity of the extinct Malagasy “horned” crocodile Voay robustus and its implications for crocodylid phylogeny and palaeoecology},
author = {Gwendal Perrichon and Yohan Pochat-Cottilloux and Davide Conedera and Pascale Richardin and Vincent Fernandez and Lionel Hautier and Jeremy E. Martin},
url = {https://anatomypubs.onlinelibrary.wiley.com/doi/abs/10.1002/ar.25367},
doi = {https://doi.org/10.1002/ar.25367},
year = {2023},
date = {2023-12-20},
journal = {The Anatomical Record},
volume = {n/a},
number = {n/a},
abstract = {Abstract Voay robustus, the extinct Malagasy “horned” crocodile, was originally considered to be the only crocodylian representative in Madagascar during most part of the Holocene. However, Malagasy crocodylian remains have had confused taxonomic attributions and recent studies have underlined that Crocodylus and Voay populations coexisted on the island for at least 7500 years. Here, we describe the inner braincase anatomy of Voay robustus using x-ray computed tomography on four specimens, to provide new anatomical information that distinguishes Voay from Crocodylus, especially features of the brain endocast and the paratympanic sinuses. Geometric morphometric analyses are performed on 3D models of the internal organs to compare statistically Voay with a subset of extant Crocodylidae. Following these comparisons, we build an endocranial morphological matrix to discuss the proposed phylogenetic affinities of Voay with Osteolaeminae from an endocranial point of view. Additionally, we discuss the use of internal characters in systematic studies and find that they can have a major impact on morphological analyses. Finally, new radiocarbon data on Voay and subfossil Crocodylus specimens are recovered between 2010 and 2750 cal BP, which confirm the cohabitation of the two species in the same area for a long period of time. We thus assess several extinction scenarios, and propose a slightly different ecology of Voay compared to Crocodylus, which could have allowed habitat partitioning on the island. Our approach complements information obtained from previous molecular and morphological phylogenies, as well as previous radiocarbon dating, together revealing past diversity and faunal turnovers in Madagascar.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Voay robustus, the extinct Malagasy “horned” crocodile, was originally considered to be the only crocodylian representative in Madagascar during most part of the Holocene. However, Malagasy crocodylian remains have had confused taxonomic attributions and recent studies have underlined that Crocodylus and Voay populations coexisted on the island for at least 7500 years. Here, we describe the inner braincase anatomy of Voay robustus using x-ray computed tomography on four specimens, to provide new anatomical information that distinguishes Voay from Crocodylus, especially features of the brain endocast and the paratympanic sinuses. Geometric morphometric analyses are performed on 3D models of the internal organs to compare statistically Voay with a subset of extant Crocodylidae. Following these comparisons, we build an endocranial morphological matrix to discuss the proposed phylogenetic affinities of Voay with Osteolaeminae from an endocranial point of view. Additionally, we discuss the use of internal characters in systematic studies and find that they can have a major impact on morphological analyses. Finally, new radiocarbon data on Voay and subfossil Crocodylus specimens are recovered between 2010 and 2750 cal BP, which confirm the cohabitation of the two species in the same area for a long period of time. We thus assess several extinction scenarios, and propose a slightly different ecology of Voay compared to Crocodylus, which could have allowed habitat partitioning on the island. Our approach complements information obtained from previous molecular and morphological phylogenies, as well as previous radiocarbon dating, together revealing past diversity and faunal turnovers in Madagascar.
Pochat-Cottilloux, Yohan; Martin, Jeremy E.; Faure-Brac, Mathieu G.; Jouve, Stéphane; Muizon, Christian; Cubo, Jorge; Lécuyer, Christophe; Fourel, François; Amiot, Romain
A multi-isotopic study reveals the palaeoecology of a sebecid from the Paleocene of Bolivia Journal Article
In: Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 625, pp. 111667, 2023, ISSN: 0031-0182.
@article{POCHATCOTTILLOUX2023111667,
title = {A multi-isotopic study reveals the palaeoecology of a sebecid from the Paleocene of Bolivia},
author = {Yohan Pochat-Cottilloux and Jeremy E. Martin and Mathieu G. Faure-Brac and Stéphane Jouve and Christian Muizon and Jorge Cubo and Christophe Lécuyer and François Fourel and Romain Amiot},
url = {https://www.sciencedirect.com/science/article/pii/S0031018223002857},
doi = {https://doi.org/10.1016/j.palaeo.2023.111667},
issn = {0031-0182},
year = {2023},
date = {2023-09-01},
urldate = {2023-01-01},
journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
volume = {625},
pages = {111667},
abstract = {Sebecids constitute a family of notosuchian crocodylomorphs of probable terrestrial habits. They are notable for having survived the Cretaceous-Paleogene mass extinction and are known until the Miocene in South America. However, ecological traits that favoured their resilience in continental ecosystems remain unknown. Here, using a multi-isotopic approach, we infer several palaeoecological traits of a sebecid from the locality of Tiupampa (Bolivia), which contains a diverse vertebrate fauna of the Early Paleocene. After having constrained the effects of diagenesis, the study of the oxygen isotope compositions of apatite phosphate allows the identification of water resources for the various studied taxa and to infer an ectothermic thermoregulation strategy for the sebecids. A terrestrial lifestyle is also supported by different oxygen isotope compositions observed between sebecids and aquatic dyrosaurid crocodylomorphs. The radiogenic strontium isotope compositions confirm the continental affinities of this fauna, with no marine input in the palaeoenvironment frequented by the different faunal elements. The calcium and carbon isotope compositions show that the sebecids from Tiupampa were at the top of a C3-based food web. Finally, a local dry environment with tropical temperatures for those specimens is inferred both from oxygen and carbon isotope compositions of their hard tissues.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Sebecids constitute a family of notosuchian crocodylomorphs of probable terrestrial habits. They are notable for having survived the Cretaceous-Paleogene mass extinction and are known until the Miocene in South America. However, ecological traits that favoured their resilience in continental ecosystems remain unknown. Here, using a multi-isotopic approach, we infer several palaeoecological traits of a sebecid from the locality of Tiupampa (Bolivia), which contains a diverse vertebrate fauna of the Early Paleocene. After having constrained the effects of diagenesis, the study of the oxygen isotope compositions of apatite phosphate allows the identification of water resources for the various studied taxa and to infer an ectothermic thermoregulation strategy for the sebecids. A terrestrial lifestyle is also supported by different oxygen isotope compositions observed between sebecids and aquatic dyrosaurid crocodylomorphs. The radiogenic strontium isotope compositions confirm the continental affinities of this fauna, with no marine input in the palaeoenvironment frequented by the different faunal elements. The calcium and carbon isotope compositions show that the sebecids from Tiupampa were at the top of a C3-based food web. Finally, a local dry environment with tropical temperatures for those specimens is inferred both from oxygen and carbon isotope compositions of their hard tissues.
Pochat-Cottilloux, Yohan; Rinder, Nicolas; Perrichon, Gwendal; Adrien, Jérôme; Amiot, Romain; Hua, Stéphane; Martin, Jeremy E.
In: Journal of Anatomy, vol. 243, no. 3, pp. 374-393, 2023.
@article{https://doi.org/10.1111/joa.13887,
title = {The neuroanatomy and pneumaticity of Hamadasuchus (Crocodylomorpha, Peirosauridae) from the Cretaceous of Morocco and its paleoecological significance for altirostral forms},
author = {Yohan Pochat-Cottilloux and Nicolas Rinder and Gwendal Perrichon and Jérôme Adrien and Romain Amiot and Stéphane Hua and Jeremy E. Martin},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/joa.13887},
doi = {https://doi.org/10.1111/joa.13887},
year = {2023},
date = {2023-06-13},
urldate = {2023-06-13},
journal = {Journal of Anatomy},
volume = {243},
number = {3},
pages = {374-393},
abstract = {Abstract We describe the endocranial structures of Hamadasuchus, a peirosaurid crocodylomorph from the late Albian-Cenomanian Kem Kem group of Morocco. The cranial endocast, associated nerves and arteries, endosseous labyrinths, and cranial pneumatization, as well as the bones of the braincase of a new specimen, are reconstructed and compared with extant and fossil crocodylomorphs, which represent different lifestyles. Cranial bones of this specimen are identified as belonging to Hamadasuchus, with close affinities with Rukwasuchus yajabalijekundu, another peirosaurid from the ‘middle’ Cretaceous of Tanzania. The endocranial structures are comparable to those of R. yajabalijekundu but also to baurusuchids and sebecids (sebecosuchians). Paleobiological traits of Hamadasuchus, such as alert head posture, ecology, and behavior are explored for the first time, using quantitative metrics. The expanded but narrow semi-circular canals and enlarged pneumatization of the skull of Hamadasuchus are linked to a terrestrial lifestyle. Continuing work on the neuroanatomy of supposedly terrestrial crocodylomorphs needs to be broadened to other groups and will allow to characterize whether some internal structures are affected by the lifestyle of these organisms.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract We describe the endocranial structures of Hamadasuchus, a peirosaurid crocodylomorph from the late Albian-Cenomanian Kem Kem group of Morocco. The cranial endocast, associated nerves and arteries, endosseous labyrinths, and cranial pneumatization, as well as the bones of the braincase of a new specimen, are reconstructed and compared with extant and fossil crocodylomorphs, which represent different lifestyles. Cranial bones of this specimen are identified as belonging to Hamadasuchus, with close affinities with Rukwasuchus yajabalijekundu, another peirosaurid from the ‘middle’ Cretaceous of Tanzania. The endocranial structures are comparable to those of R. yajabalijekundu but also to baurusuchids and sebecids (sebecosuchians). Paleobiological traits of Hamadasuchus, such as alert head posture, ecology, and behavior are explored for the first time, using quantitative metrics. The expanded but narrow semi-circular canals and enlarged pneumatization of the skull of Hamadasuchus are linked to a terrestrial lifestyle. Continuing work on the neuroanatomy of supposedly terrestrial crocodylomorphs needs to be broadened to other groups and will allow to characterize whether some internal structures are affected by the lifestyle of these organisms.
Pochat-Cottilloux, Yohan; Perrier, Vincent; Amiot, Romain; Martin, Jeremy E.
In: Papers in Palaeontology, vol. 9, no. 2, pp. e1485, 2023, (e1485 PALA-03-22-5263-OA.R2).
@article{https://doi.org/10.1002/spp2.1485,
title = {A peirosaurid mandible from the Albian–Cenomanian (Lower Cretaceous) of Algeria and the taxonomic content of Hamadasuchus (Crocodylomorpha, Peirosauridae)},
author = {Yohan Pochat-Cottilloux and Vincent Perrier and Romain Amiot and Jeremy E. Martin},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/spp2.1485},
doi = {https://doi.org/10.1002/spp2.1485},
year = {2023},
date = {2023-03-29},
urldate = {2023-01-01},
journal = {Papers in Palaeontology},
volume = {9},
number = {2},
pages = {e1485},
abstract = {Abstract Peirosaurids form an extinct clade of terrestrial crocodylomorphs from the Cretaceous of Africa and South America. Here, we describe a new mandibular ramus attributable to Hamadasuchus cf. rebouli from the Albian–Cenomanian of La Gara Samani (Algeria). We propose an emended diagnosis for this taxon, originally described from a left dentary fragment from the Kem Kem Group of Morocco and discuss the assignment of the specimens currently referred to it. Using ontogenetic series of extant crocodylians, we show that several mandibular characters commonly used to differentiate between close taxa instead record intraspecific or ontogenetic variability. In contrast, reliable mandibular characters enable us to propose that the current taxonomic content of Hamadasuchus rebouli should be reduced to three specimens, pending future description of relatable cranial remains. Finally, we demonstrate the importance of mandibular characters in phylogenies, by recovering the new specimen from La Gara Samani as closely related to North African peirosaurids on the basis of a data matrix designed solely on mandibular characters.},
note = {e1485 PALA-03-22-5263-OA.R2},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Peirosaurids form an extinct clade of terrestrial crocodylomorphs from the Cretaceous of Africa and South America. Here, we describe a new mandibular ramus attributable to Hamadasuchus cf. rebouli from the Albian–Cenomanian of La Gara Samani (Algeria). We propose an emended diagnosis for this taxon, originally described from a left dentary fragment from the Kem Kem Group of Morocco and discuss the assignment of the specimens currently referred to it. Using ontogenetic series of extant crocodylians, we show that several mandibular characters commonly used to differentiate between close taxa instead record intraspecific or ontogenetic variability. In contrast, reliable mandibular characters enable us to propose that the current taxonomic content of Hamadasuchus rebouli should be reduced to three specimens, pending future description of relatable cranial remains. Finally, we demonstrate the importance of mandibular characters in phylogenies, by recovering the new specimen from La Gara Samani as closely related to North African peirosaurids on the basis of a data matrix designed solely on mandibular characters.
2022
Pochat-Cottilloux, Yohan; Martin, Jeremy E.; Amiot, Romain; Cubo, Jorge; Buffrénil, Vivian
A survey of osteoderm histology and ornamentation among Crocodylomorpha: A new proxy to infer lifestyle? Journal Article
In: Journal of Morphology, vol. 284, no. 1, pp. e21542, 2022.
@article{https://doi.org/10.1002/jmor.21542,
title = {A survey of osteoderm histology and ornamentation among Crocodylomorpha: A new proxy to infer lifestyle?},
author = {Yohan Pochat-Cottilloux and Jeremy E. Martin and Romain Amiot and Jorge Cubo and Vivian Buffrénil},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/jmor.21542},
doi = {https://doi.org/10.1002/jmor.21542},
year = {2022},
date = {2022-12-15},
urldate = {2023-01-01},
journal = {Journal of Morphology},
volume = {284},
number = {1},
pages = {e21542},
abstract = {Abstract Osteoderms of eight extant and extinct species of crocodylomorphs are studied histologically and morphologically. Most osteoderms display the typical “crocodilian” structure with a woven-fibered matrix surrounded by an upper and a lower parallel fibered matrix. The dorsal ornamentation of those specimens consists of a pit-and-ridge structure, with corresponding remodeling mechanisms. However, an osteoderm of Iberosuchus, studied here for the first time, differs in being nearly devoid of ornamentation; moreover, it shows strong bundles of straight Sharpey's fibers perpendicular to the surface in its lateral and dorsal walls, along with a rough plywood-like structure in its basal plate. This suggests that this osteoderm was more deeply anchored within the dermis than the other osteoderms studied hitherto. This peculiar structure might have been linked to a terrestrial ecology and a specific thermoregulation strategy. Some other notosuchians in our sample do not exhibit ornamentation on their osteoderms, as opposed to neosuchians. Considering current interpretations of osteoderm function(s) in crocodilians, our observations are discussed in reference to possible ecophysiological peculiarities of Notosuchia in general, and Iberosuchus in particular.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract Osteoderms of eight extant and extinct species of crocodylomorphs are studied histologically and morphologically. Most osteoderms display the typical “crocodilian” structure with a woven-fibered matrix surrounded by an upper and a lower parallel fibered matrix. The dorsal ornamentation of those specimens consists of a pit-and-ridge structure, with corresponding remodeling mechanisms. However, an osteoderm of Iberosuchus, studied here for the first time, differs in being nearly devoid of ornamentation; moreover, it shows strong bundles of straight Sharpey's fibers perpendicular to the surface in its lateral and dorsal walls, along with a rough plywood-like structure in its basal plate. This suggests that this osteoderm was more deeply anchored within the dermis than the other osteoderms studied hitherto. This peculiar structure might have been linked to a terrestrial ecology and a specific thermoregulation strategy. Some other notosuchians in our sample do not exhibit ornamentation on their osteoderms, as opposed to neosuchians. Considering current interpretations of osteoderm function(s) in crocodilians, our observations are discussed in reference to possible ecophysiological peculiarities of Notosuchia in general, and Iberosuchus in particular.
Pochat-Cottilloux, Yohan; Allain, Ronan; Lasseron, Maxime
Microvertebrate fauna from Gadoufaoua (Niger, Aptian, Early Cretaceous) Journal Article
In: Comptes Rendus Palevol, no. 41, 2022, ISSN: 1777-571X.
@article{POCHATCOTTILLOUX2022,
title = {Microvertebrate fauna from Gadoufaoua (Niger, Aptian, Early Cretaceous)},
author = {Yohan Pochat-Cottilloux and Ronan Allain and Maxime Lasseron},
url = {http://dx.doi.org/10.5852/cr-palevol2022v21a41},
doi = {10.5852/cr-palevol2022v21a41},
issn = {1777-571X},
year = {2022},
date = {2022-12-01},
urldate = {2022-12-01},
journal = {Comptes Rendus Palevol},
number = {41},
publisher = {Museum National D’Histoire Naturelle},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Perrichon, Gwendal; Richardin, Pascale; Martin, Jeremy E.; Adrien, Jerome
The oldest occurrence of Crocodylus in Madagascar and the Holocene crocodylian turnover Journal Article
In: Journal of Vertebrate Paleontology, vol. 41, no. 6, pp. e2063058, 2022.
@article{doi:10.1080/02724634.2021.2063058,
title = {The oldest occurrence of Crocodylus in Madagascar and the Holocene crocodylian turnover},
author = {Gwendal Perrichon and Pascale Richardin and Jeremy E. Martin and Jerome Adrien},
url = {https://doi.org/10.1080/02724634.2021.2063058},
doi = {10.1080/02724634.2021.2063058},
year = {2022},
date = {2022-05-27},
urldate = {2022-05-27},
journal = {Journal of Vertebrate Paleontology},
volume = {41},
number = {6},
pages = {e2063058},
publisher = {Taylor & Francis},
abstract = {The island of Madagascar is home to a distinctive fauna and flora whose biogeographic history is not fully understood. Today’s crocodylian population consists of a single species, the Nile crocodile, Crocodylus niloticus, whose colonization of the island may be very recent. In Madagascar, the genus Crocodylus has so far been described from a single subfossil specimen dated at 385 years cal BP, offering limited perspectives for discussing the timing of its arrival. On the other hand, another crocodyline, the now-extinct endemic Voay robustus, has been reported from several late Holocene localities throughout the island. Because of the earlier age of Voay robustus, it has been suggested that Crocodylus followed the extinction of this endemic species. Here, we report on a significantly older occurrence of the genus Crocodylus, between 7670 and 7510 years cal BP. The taxonomic identity of crocodylian subfossil specimens throughout Madagascar should be reevaluated in the context of this new occurrence, which could alter hypotheses of crocodylian turnover and the potential human impacts on the island.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The island of Madagascar is home to a distinctive fauna and flora whose biogeographic history is not fully understood. Today’s crocodylian population consists of a single species, the Nile crocodile, Crocodylus niloticus, whose colonization of the island may be very recent. In Madagascar, the genus Crocodylus has so far been described from a single subfossil specimen dated at 385 years cal BP, offering limited perspectives for discussing the timing of its arrival. On the other hand, another crocodyline, the now-extinct endemic Voay robustus, has been reported from several late Holocene localities throughout the island. Because of the earlier age of Voay robustus, it has been suggested that Crocodylus followed the extinction of this endemic species. Here, we report on a significantly older occurrence of the genus Crocodylus, between 7670 and 7510 years cal BP. The taxonomic identity of crocodylian subfossil specimens throughout Madagascar should be reevaluated in the context of this new occurrence, which could alter hypotheses of crocodylian turnover and the potential human impacts on the island.
2021
Pochat-Cottilloux, Yohan; Martin, Jeremy E.; Jouve, Stéphane; Perrichon, Gwendal; Adrien, Jérome; Salaviale, Céline; Muizon, Christian; Cespedes, Ricardo; Amiot, Romain
The neuroanatomy of Zulmasuchus querejazus (Crocodylomorpha, Sebecidae) and its implications for the paleoecology of sebecosuchians Journal Article
In: The Anatomical Record, vol. 305, no. 10, pp. 2708-2728, 2021.
@article{https://doi.org/10.1002/ar.24826,
title = {The neuroanatomy of Zulmasuchus querejazus (Crocodylomorpha, Sebecidae) and its implications for the paleoecology of sebecosuchians},
author = {Yohan Pochat-Cottilloux and Jeremy E. Martin and Stéphane Jouve and Gwendal Perrichon and Jérome Adrien and Céline Salaviale and Christian Muizon and Ricardo Cespedes and Romain Amiot},
url = {https://anatomypubs.onlinelibrary.wiley.com/doi/abs/10.1002/ar.24826},
doi = {https://doi.org/10.1002/ar.24826},
year = {2021},
date = {2021-11-26},
urldate = {2021-11-26},
journal = {The Anatomical Record},
volume = {305},
number = {10},
pages = {2708-2728},
abstract = {Abstract The endocranial structures of the sebecid crocodylomorph Zulmasuchus querejazus (MHNC 6672) from the Lower Paleocene of Bolivia are described in this article. Using computed tomography scanning, the cranial endocast, associated nerves and arteries, endosseous labyrinths, and cranial pneumatization are reconstructed and compared with those of extant and fossil crocodylomorphs, representative of different ecomorphological adaptations. Z. querejazus exhibits an unusual flexure of the brain, pericerebral spines, semicircular canals with a narrow diameter, as well as enlarged pharyngotympanic sinuses. First, those structures allow to estimate the alert head posture and hearing capabilities of Zulmasuchus. Then, functional comparisons are proposed between this purportedly terrestrial taxon, semi-aquatic, and aquatic forms (extant crocodylians, thalattosuchians, and dyrosaurids). The narrow diameter of the semicircular canals but expanded morphology of the endosseous labyrinths and the enlarged pneumatization of the skull compared to other forms indeed tend to indicate a terrestrial lifestyle for Zulmasuchus. Our results highlight the need to gather new data, especially from altirostral forms in order to further our understanding of the evolution of endocranial structures in crocodylomorphs with different ecomorphological adaptations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Abstract The endocranial structures of the sebecid crocodylomorph Zulmasuchus querejazus (MHNC 6672) from the Lower Paleocene of Bolivia are described in this article. Using computed tomography scanning, the cranial endocast, associated nerves and arteries, endosseous labyrinths, and cranial pneumatization are reconstructed and compared with those of extant and fossil crocodylomorphs, representative of different ecomorphological adaptations. Z. querejazus exhibits an unusual flexure of the brain, pericerebral spines, semicircular canals with a narrow diameter, as well as enlarged pharyngotympanic sinuses. First, those structures allow to estimate the alert head posture and hearing capabilities of Zulmasuchus. Then, functional comparisons are proposed between this purportedly terrestrial taxon, semi-aquatic, and aquatic forms (extant crocodylians, thalattosuchians, and dyrosaurids). The narrow diameter of the semicircular canals but expanded morphology of the endosseous labyrinths and the enlarged pneumatization of the skull compared to other forms indeed tend to indicate a terrestrial lifestyle for Zulmasuchus. Our results highlight the need to gather new data, especially from altirostral forms in order to further our understanding of the evolution of endocranial structures in crocodylomorphs with different ecomorphological adaptations.