Paleontologists in India have identified a new genus and species of proterosuchid reptile from both new and historically collected specimens.
Life reconstruction of Samsarasuchus pamelae. Image credit: Gabriel Lio.
Samsarasuchus pamelae roamed our planet during the Early Triassic epoch, 251.5 million years ago.
The ancient reptile was a member of Proterosuchidae, a small family of early archosauriforms.
Proterosuchids are known from the latest Permian of Eastern Europe and the earliest Triassic of South Africa and China.
These creatures were slender, long-snouted reptiles that superficially resembled crocodiles.
They measured between 1.5 and 4 m in length, were adapted to hearing low frequency sounds, and probably had semi-aquatic habits.
Their most characteristic feature was a distinct down-turning of the front of the upper jaw (premaxilla).
“The origin of Archosauromorpha can be traced back to the middle-late Permian, with a few occurrences in Western and Eastern Europe, continental Africa and probably South America,” said University of Birmingham paleontologist Martín Ezcurra and his colleagues.
“The presence of Permian archosauriforms implies that the origin of the main non-archosauriform archosauromorph clades should also extend back well into the Permian, although Paleozoic fossil evidence is still lacking for the vast majority of these groups (e.g. tanystropheids, rhynchosaurs, allokotosaurs, prolacertids).”
“The only archosauromorph lineage with body fossils on both sides of the vertebrate fossil-defined Permo-Triassic boundary is Proterosuchidae,” they said.
“The members of this clade are characterized by a low and elongated skull with a large and strongly downturned premaxilla, moderately long cervical series, relatively gracile limb bones and a plesiomorphic sprawling locomotion.”
“The unusual oversized and downturned premaxilla of proterosuchids became increasingly pronounced and distinctive through ontogeny, and mutual social and/or sexual selection may be an explanation for the function and evolutionary origin of this bizarre feature.”
Several fossilized cervical vertebrae of Samsarasuchus pamelae were uncovered on January 18, 2015 from the upper Panchet Formation near Deoli village in West Bengal, India.
The holotype and paratype specimens were found 10 m apart from one another in approximately the same stratigraphic level.
“We recovered Samsarasuchus pamelae as a member of a novel clade within Proterosuchidae, named as the new subfamily Chasmatosuchinae,” the paleontologists said.
“Chasmatosuchinae also includes forms from Eastern Europe, Brazil and Australia.”
“The study of Samsarasuchus pamelae and the other early archosauriform bones from the Panchet Formation has improved our knowledge of proterosuchids, confirming the high potential of the Indian unit to shed light on the aftermath of the end-Permian mass extinction and, in particular, on the taxonomy and phylogeny of early archosauriforms,” they added.
“The search for and discovery of new more complete proterosuchid specimens will be crucial to reaching a more robust understanding of the anatomy, taxonomy, phylogeny and macroevolution of this clade and its implications for the understanding of the aftermath of the end-Permian mass extinction.”
The findings were published in the October 2023 issue of the journal Royal Society Open Science.
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M.D. Ezcurra et al. 2023. A new archosauriform species from the Panchet Formation of India and the diversification of Proterosuchidae after the end-Permian mass extinction. R. Soc. Open Sci 10: 230387; doi: 10.1098/rsos.230387
