The megafaunal extinction was one of the most significant faunal events seen in the Quaternary. The causes of this extinction are unclear. Both humans and climate change have been implicated. While much research on this event has been conducted on other continents, the Indian subcontinent as a whole has never been studied in this context. Here, using the largest compilation of Indian mammal occurrences from the last 100,000 years, I investigate patterns of diversity through time in order to understand this extinction event in the subcontinent. Faunal lists and ages were collected from published literature. Herbivores are best represented in the Indian fossil record, so analyses were restricted to artiodactyls, perissodactyls, and proboscideans. Pleistocene collections of taxa were binned into marine isotope stages, while Holocene collections were divided into tree bins: 10ka-4ka, 4ka-2ka, 2ka-present. Alpha diversity was estimated for each bin. Additionally body mass, and diet (using the hypsodonty index) were also determined for the taxa. Body mass and hypsodonty distributions were constructed for each time bin to determine if there was size or dietary selectivity in the extinctions. Finally, these patterns were compared to changes in the intensity of the southwest monsoons.
Results/Conclusions
Of the taxa sampled, two proboscideans, one species of hippo, and one species of horse go extinct. However, these extinctions are staggered. Both proboscideans go extinct after MIS3, while the hippo and horse persist up until the latest Pleistocene. Species of Bos and Bubalus undergo domestication, and are therefore not considered extinct in this study. The Indian rhinoceros is extirpated from the peninsular region after 2000ybp. Overall, the Indian peninsular region and Gangetic plain retained 70% of it’s herbivores. This extinction magnitude is similar to that seen in Africa. Analyses of body mass showed that large bodied taxa did preferentially go extinct, but several taxa of equally large megafauna persisted. Dietary analyses showed no selectivity. Correlations with monsoon intensity show that the proboscideans go extinct at the onset of, or soon into MIS2, which is characterized by a weakening of the SW monsoons. While the hippos persisted through this interval, they go extinct soon after. It can be hypothesized that these taxa were more water dependent, and could not survive prolonged stretches of weak monsoons. Further investigations will shed more light on these intriguing patterns of large mammal extinctions in the Indian subcontinent.