Dispersal vs. vicariance: the origin of India’s extant tetrapod fauna

Abstract

Given the Indian block’s ancient association with Gondwana and subsequent separation from Africa, then Madagascar, then the Seychelles, vicariance has often been invoked to explain the distribution of some of India’s extant biota that might have had Gondwanan origins. Here I review phylogenetic studies and fossil data of Indian tetrapods to ascertain the contribution of dispersal and vicariance in shaping the assemblage. Paleogene dispersal into India accounts for almost all of the tetrapod clades in India. Vicariance is invoked for three groups, all fossorial; the caecilians, the frog family Nasikabatrachidae and the blindsnake family Gerrhopilidae. This review concludes that practically all of India’s Late Cretaceous tetrapod fauna (of Gondwanan origin) was extirpated during the Cretaceous-Paleogene mass extinction, which may have been exacerbated by the coeval volcanism associated with the emplacement of the Deccan Trap large igneous province. Subsequently, the tetrapod fauna was built up by incoming elements as India advanced towards Asia, docking with the continent in the Paleogene.