South Asian river dolphin display the variances needed to support their classification as separate species. Thus, at present, a single species with two subspecies is recognized in the genus "Platanista", "P. g. gangetica" (Ganges river dolphin) and "P. g. minor" (Indus river dolphin). An assessment of divergence rates in mitochondrial DNA of the two subspecies indicates that they diverged from a common ancestor around 550,000 years ago. This ancestor is thought to have been a marine Platanistid inhabiting the epi-continental seas in South Asia during the sea level rises in the middle Miocene. The earliest fossil identified as belonging to the species is only
John Anderson (zoologist) and compared with "Orcaella fluminalis" and the Gangetic dolphin, "Plantanista gangetica". In 1875-6 he travelled to the same area under Colonel Horace Browne. This was cut short due to the murder of the consular officer Augustus Raymond Margary. Anderson made a third expedition for the Indian Museum in 1881–2 to the Mergui archipelago, Burma. Anderson made comparative studies of anatomy of the species that he collected. He worked on reptiles, birds as well as mammals such as of the genus "Hylomys". He also wrote on the ethnology of the Selungs of the Mergui archipelago. Many of the plant specimens that