Current developments in Paleogene vertebrate palaeontology in view of India’s final drift phase and India–Eurasia docking: an appraisal

This article aims to present an overview of the Paleogene vertebrate faunal records, especially mammals, with an emphasis on research conducted within the last 5 years i.e., from 2019 to 2023. Recent developments highlight the significance of vertebrate fossil records (particularly that of mammals) in our understanding of the origin, evolution, and historical distributions close to the India-Eurasia docking phase. Overall, the fossil records of early Paleogene vertebrates indicate that India was a hotspot for biodiversity for several orders of terrestrial (such perissodactyls, primates, and artiodactyls) and marine mammals (like cetaceans and sirenians). The directions of biotic migrations between India and its surrounding continents between the ~ 66 to ~ 50 Ma time slice remains to be fully understood; however, the sweepstakes and/or island-hopping dispersal mechanisms were the most likely mode of migration for the small- and medium-sized mammals. Additionally, according to a recent study, plausible existence of corridor(s) for secular migration allowed for faunal exchanges between India and Eurasia close to ~ 56–57 Ma, particularly for the large-sized mammals (> 35 kg) (e.g., cambaythere perissodactyls). Further, there is now a revived interest in the early Paleogene vertebrate palaeontology of India due to recent data on biostratigraphically constrained Paleocene and early-middle Eocene vertebrate records (such as fish, reptiles, and amphibians along with associated coprolite ichnofossils) from the western and northeastern regions of India.