Sissokosuchus, new itasuchid notosuchian from Early Cretaceous of Mali + notosuchian growth patterns indicated by osteoderms
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Ben Creisler
Jun 23, 2025, 10:25:05 AMJun 23
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Ben Creisler
Eric Wilberg, Robert V. Hill, Thomas R. Pascucci, Eric M. Roberts, Mamadou L. Bouaré & Maureen A. O’Leary (2025)
A new itasuchid (Crocodyliformes, Notosuchia) from the Early Cretaceous of Mali and the ancient Paleo-Tegama river system of Gondwana
Journal of Vertebrate Paleontology e2505473
doi: https://doi.org/10.1080/02724634.2025.2505473
https://www.tandfonline.com/doi/full/10.1080/02724634.2025.2505473
We describe a new genus and species of notosuchian crocodyliform from the “Continental Intercalaire” of the Republic of Mali represented by cranial, mandibular, and postcranial material. Phylogenetic analysis recovers the new taxon, Sissokosuchus maliensis, within Itasuchidae as the sister taxon to Barreirosuchus, and deeply nested within an otherwise South American radiation. Sissokosuchus is the first itasuchid recognized from the Lower Cretaceous “Continental Intercalaire” of West Africa (with Fortignathus felixi potentially representing a second). Sissokosuchus possesses the apomorphic dentary alveolar couplet morphology present in Itasuchus and other later diverging itasuchids. Our analysis also supports a clade-level dichotomy in rostral morphology: Itasuchidae is dominated by narrower, platyrostral taxa and Peirosauridae by oreinirostral taxa. Sedimentology of the site suggests that Sissokosuchus is associated with a large, ancient fluvial channel system. Paleocurrents and detrital zircon data indicate that sediments were derived from myriad sources to the south and east. Our work corroborates hypotheses indicating westward paleoflow of stratigraphically correlative Aptian–Albian fluvial strata in Niger (that preserve similar taxa) into Mali. We hypothesize that a transcontinental river system, here named the Paleo-Tegama River System, was present during this time draining west out of Niger through Mali and into the Tethys Sea. This paleodrainage system would have acted as a late-lasting inland faunal corridor between South America and West Africa, via the West and Central African Rift System, prior to final Gondwanan break-up, or a post break-up dispersal route via the Tethys, for semiaquatic West African crocodyliforms to reach South America, or vice versa.
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Recent papers:
Sissokosuchus maliensis gen. et sp. nov.
Eric Wilberg, Robert V. Hill, Thomas R. Pascucci, Eric M. Roberts, Mamadou L. Bouaré & Maureen A. O’Leary (2025)
A new itasuchid (Crocodyliformes, Notosuchia) from the Early Cretaceous of Mali and the ancient Paleo-Tegama river system of Gondwana
Journal of Vertebrate Paleontology e2505473
doi: https://doi.org/10.1080/02724634.2025.2505473
https://www.tandfonline.com/doi/full/10.1080/02724634.2025.2505473
We describe a new genus and species of notosuchian crocodyliform from the “Continental Intercalaire” of the Republic of Mali represented by cranial, mandibular, and postcranial material. Phylogenetic analysis recovers the new taxon, Sissokosuchus maliensis, within Itasuchidae as the sister taxon to Barreirosuchus, and deeply nested within an otherwise South American radiation. Sissokosuchus is the first itasuchid recognized from the Lower Cretaceous “Continental Intercalaire” of West Africa (with Fortignathus felixi potentially representing a second). Sissokosuchus possesses the apomorphic dentary alveolar couplet morphology present in Itasuchus and other later diverging itasuchids. Our analysis also supports a clade-level dichotomy in rostral morphology: Itasuchidae is dominated by narrower, platyrostral taxa and Peirosauridae by oreinirostral taxa. Sedimentology of the site suggests that Sissokosuchus is associated with a large, ancient fluvial channel system. Paleocurrents and detrital zircon data indicate that sediments were derived from myriad sources to the south and east. Our work corroborates hypotheses indicating westward paleoflow of stratigraphically correlative Aptian–Albian fluvial strata in Niger (that preserve similar taxa) into Mali. We hypothesize that a transcontinental river system, here named the Paleo-Tegama River System, was present during this time draining west out of Niger through Mali and into the Tethys Sea. This paleodrainage system would have acted as a late-lasting inland faunal corridor between South America and West Africa, via the West and Central African Rift System, prior to final Gondwanan break-up, or a post break-up dispersal route via the Tethys, for semiaquatic West African crocodyliforms to reach South America, or vice versa.
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Alex Gabriel Cajado, Carlos Eduardo Maia de Oliveira, Marco Brandalise de Andrade, William Roberto Nava & Rodrigo Miloni Santucci (2025)
Osteoderm microstructure indicates ontogenetic shifts in the growth pattern of some Cretaceous notosuchians (Crocodylomorpha)
Journal of Anatomy (advance online publication)
doi: https://doi.org/10.1111/joa.70012
https://onlinelibrary.wiley.com/doi/10.1111/joa.70012
A characteristic common to almost all crocodylomorphs, whether living or extinct, is the presence of a dermal skeleton. This covering is composed of bones known as osteoderms or dermal plates/scutes, which are interconnected by fibrous tissues. Osteoderms play essential roles in the biology of crocodylomorphs, and vary in size, shape, ornamentation pattern, and functions according to the species. This study analyzed the osteoderms of fossil species of four fossil crocodylomorphs taxa from the Upper Cretaceous of the Bauru Group and compared their morphological characteristics with other living and extinct lineages, including Candidodontidae and fossil Caimaninae. Sampling included osteoderms from different regions of the body and individuals of different ontogenetic stages. The osteoderms analyzed originate from distinct clades of crocodylomorphs (Peirosauridae, Baurusuchidae, Sphagesauridae, and the spaghesaurian Mariliasuchus), presenting distinct external morphologies at the macroscopic level. The histological analysis confirmed the similarities seen in distinct clades of crocodylomorphs (Peirosauridae, Baurusuchidae, Sphagesauridae, and Mariliasuchus), despite highly divergent macroscopic morphology. In all cases, the bony matrix is characterized by parallel and interwoven fibers, with secondary osteons much larger than the primary ones, indicating a process of bone resorption. Growth lines also provide information on the minimum age of the individuals at the time of death. Histological differences in the osteoderms of baurusuchid of different ontogenetic stages indicate a back-to-front progression in the reabsorption process, akin to the progressive ontogenetic fusion of neurocentral sutures seen in the vertebral spine of crocodylomorphs. A shift in the position of the parasagittal crest through ontogeny indicates that the growth process of the osteoderm is not symmetric at least in Baurusuchidae, and that individuals of different ages are expected to present meaningful macroscopic shifts in the morphology of their osteoderms. Peirosauridae ornamentation pattern also varies during ontogeny since pits present in early ontogenetic states are covered/obliterated by subsequent layers of bone that assume a more regular aspect.
Osteoderm microstructure indicates ontogenetic shifts in the growth pattern of some Cretaceous notosuchians (Crocodylomorpha)
Journal of Anatomy (advance online publication)
doi: https://doi.org/10.1111/joa.70012
https://onlinelibrary.wiley.com/doi/10.1111/joa.70012
A characteristic common to almost all crocodylomorphs, whether living or extinct, is the presence of a dermal skeleton. This covering is composed of bones known as osteoderms or dermal plates/scutes, which are interconnected by fibrous tissues. Osteoderms play essential roles in the biology of crocodylomorphs, and vary in size, shape, ornamentation pattern, and functions according to the species. This study analyzed the osteoderms of fossil species of four fossil crocodylomorphs taxa from the Upper Cretaceous of the Bauru Group and compared their morphological characteristics with other living and extinct lineages, including Candidodontidae and fossil Caimaninae. Sampling included osteoderms from different regions of the body and individuals of different ontogenetic stages. The osteoderms analyzed originate from distinct clades of crocodylomorphs (Peirosauridae, Baurusuchidae, Sphagesauridae, and the spaghesaurian Mariliasuchus), presenting distinct external morphologies at the macroscopic level. The histological analysis confirmed the similarities seen in distinct clades of crocodylomorphs (Peirosauridae, Baurusuchidae, Sphagesauridae, and Mariliasuchus), despite highly divergent macroscopic morphology. In all cases, the bony matrix is characterized by parallel and interwoven fibers, with secondary osteons much larger than the primary ones, indicating a process of bone resorption. Growth lines also provide information on the minimum age of the individuals at the time of death. Histological differences in the osteoderms of baurusuchid of different ontogenetic stages indicate a back-to-front progression in the reabsorption process, akin to the progressive ontogenetic fusion of neurocentral sutures seen in the vertebral spine of crocodylomorphs. A shift in the position of the parasagittal crest through ontogeny indicates that the growth process of the osteoderm is not symmetric at least in Baurusuchidae, and that individuals of different ages are expected to present meaningful macroscopic shifts in the morphology of their osteoderms. Peirosauridae ornamentation pattern also varies during ontogeny since pits present in early ontogenetic states are covered/obliterated by subsequent layers of bone that assume a more regular aspect.
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