Fossil murine rodents as ancient monsoon indicators of the Indian subcontinent

Abstract

The ecomorphological aspects of murine rodent dentition were analyzed by comparing the relationship between fossils and their extant counterparts. Another aspect explored is the broad correlation of species richness vs rainfall and temperature data of an area. Integration of these results has provided a broad picture of the monsoonal conditions (rainfall, temperature and vegetation) prevailing during the Late Middle Miocene to Late Miocene (13–6.4 Ma) and Pliocene (∼5–1.8 Ma) times in the northwestern part of the Indian subcontinent. Terminal Pleistocene Kurnool Cave murine fauna also provides some clues regarding the past climatic conditions in this part of Andhra Pradesh. The results indicate that the Late Miocene possibly had monsoonal conditions quite different from that of the present day, as none of the extant taxa cluster with the Late Miocene taxa. The northwestern part of the Indian subcontinent received rainfall between 1000 and 2000 mm in the Early Pliocene (5–4 Ma) and that in the Late Pliocene was between 2000 and 4000 mm. Late Pliocene diversity of murine rodents reflects the existence of a diverse spectrum of ecological niches, mainly open grassland/savanna conditions interspersed with dry/wet deciduous and semi-evergreen forests. Terminal Pleistocene around Kurnool Caves (Andhra Pradesh) was relatively drier compared to the Pliocene with rainfall ranging between 600 and 1000 mm.