A New Erythrosuchid Archosauriform from the Middle Triassic Yerrapalli Formation of South-Central India

Abstract

Erythrosuchid archosauriforms are quadrupedal carnivorous reptiles with a proportionally huge skull. They represent one of the first evolutionary radiations of medium to large predatory diapsids after the Permo–Triassic mass extinction. Erythrosuchids are known from Lower–Middle Triassic rocks of South Africa, Russia, and China, and there have been preliminary reports from the Middle Triassic Yerrapalli Formation of south-central India. Here we describe, compare and figure for the first time these Indian erythrosuchid remains. We erect the new genus and species Bharitalasuchus tapani based on a holotype and paratype that preserve tooth-bearing cranial fragments, at least 17 presacral vertebrae, some ribs and probable intercentra, and partial shoulder and pelvic girdles and hindlimb and allow recognizing a series of autapomorphies and unique combination of character states among erythrosuchids. Our phylogenetic analysis recovered Bharitalasuchus tapani most closely related to Shansisuchus shansisuchus and Chalishevia cothurnata from the late Anisian of China and Ladinian of Russia, respectively. The phylogenetic affinities of this new taxon and a revision of the tetrapod assemblage of the Yerrapalli Formation shed light on the age of this unit. The presence of the Wadiasaurus-Rechnisaurus-Bharitalasuchus association in the Yerrapalli Formation closely resembles the Sinokannemeyeria-Shansisuchus dicynodont-erythrosuchid association of late Anisian to early Ladinian Chinese units. This evidence supports a post-early–middle Anisian age, even possibly early Ladinian, for the Yerrapalli Formation. The presence of possibly one of the last erythrosuchids in India would indicate that the clade still retained both a northern and southern Pangean distribution before its extinction.