Faunal and environmental change surrounding the extinction of Sivapithecus, a Miocene hominoid, in the Siwaliks of Pakistan

The purpose of this investigation is to determine the preferred habitats of Sivapithecus and whether changes in habitat or climate may have led to its extinction. This research incorporates both dental microwear and carbon and oxygen stable isotopic analyses from a wide range of mammalian species in the Miocene Siwaliks of Pakistan to reconstruct and compare paleohabitats, climates, and dietary adaptations just before and just after the extinction of Sivapithecus. Habitat and climate reconstructions address forest type, mosaic of vegetation on the landscape, fruit availability, and seasonality of the precipitation regime.; Isotopic evidence indicates that the Siwaliks were characterized by a vegetation mosaic of forest, woodland, and open habitats as early as 9.3 Ma. By 8.1 Ma, much of the forest was replaced, but not completely eliminated, by more open habitat, including patches of C4 grass. This vegetation mosaic supported fauna which exploited a range of habitats. Microwear analyses indicate that many species, including Sivapithecus, suids, tragulids, and bovids, were as dependant on fruit as their modern counterparts. Most of these species go extinct over the time interval sampled, with species most dependant on closed habitat or fruit going extinct first. The pattern of extinctions combined with vegetation mosaic reconstructions suggests forest fragmentation over time, leading to frugivore extinctions, including Sivapithecus.; Isotopic reconstructions of the precipitation regime from 10.0 to 6.3 Ma are similar to regimes experienced in southern China today. These reconstructions suggest a dry season of 5--6 months, with an intense rainy season. Amount of annual rainfall decreases in time and likely resulted in a shift from wet monsoon forests to dry monsoon forests. Monsoon forests do not support great apes today. It is unlikely that Sivapithecus differed from modern apes in habitat or food requirements. Therefore, Miocene forests probably differed from modern analogues in the spatio-temporal availability of fruit. Miocene forests may have provided a greater diversity of fruiting species. Alternatively, higher atmospheric CO2 levels may have resulted in greater plant productivity as well as greater water-use efficiency, allowing Miocene monsoon forests to mimic modern rainforests in fruit availability and therefore in the fauna they could support.