ADDITIONAL INFORMATION ON THE ARCHOSAURIFORMS FROM THE LOWERMOST TRIASSIC PANCHET FORMATION OF INDIA AND THE AFFINITIES OF “TERATOSAURUS(?) BENGALENSIS”

Abstract

The Panchet Formation of northeastern India preserves an Induan (earliest Triassic) vertebrate assemblage with only one valid archosauromorph species, the proterosuchid Samsarasuchus pamelae. Two other archosauromorph species have been named for this unit: “Ankistrodon indicus” and “Teratosaurus(?) bengalensis”. “Ankistrodon indicus”, based on a fragment of maxilla with two partial teeth, is indistinguishable from other proterosuchid species and is considered a nomen dubium. “Teratosaurus(?) bengalensis” is represented by an isolated, almost complete tooth that was distinguished from “Ankistrodon indicus” in the presence of mesial denticles. “Teratosaurus(?) bengalensis” is also indistinguishable from other valid proterosuchid species and considered likely a nomen dubium. However, it remains unresolved if “Teratosaurus(?) bengalensis” represents a second Panchet archosauromorph species different from Samsarasuchus pamelae and “Ankistrodon indicus” because the presence of mesial denticles cannot be determined in these species due to their incompleteness. Here we describe two new Panchet Proterosuchidae specimens collected from the same locality as the holotypes of the three above-mentioned species. These new specimens are maxillary fragments and one of them has almost complete teeth with mesial denticles on the apical portion of the crowns, as in “Teratosaurus(?) bengalensis.” The rest of their morphology is congruent with that of Samsarasuchus pamelae and “Ankistrodon indicus.” As a result, the specimens reported here expand our anatomical knowledge of the Panchet archosauriform assemblage and indicate that there is no current evidence for the presence of more than one valid archosauromorph species in the Panchet Formation.

Keywords

• Archosauriformes
• Proterosuchidae
• Induan
• Taxonomy