Arktocara ("Platanista gangetica") which inhabits the tropics, making it its closest living relative. Allodelphinidae also included the genera "Allodelphis", "Goedertius", "Ninjadelphis", and "Zarhinocetus". Its discovery further reinforces the theory that the Platanistoidea river dolphins originated in the oceans. Of the characteristics it shared with other platanistoids was a cylindrical projection of the periotic bone in the ear, deeply grooved rostral sutures on the beak, the widening of the cranium, a depression on the roof of the orbit in the eye socket, a smaller exposed palatine bone in the roof of the mouth, an elongated and convex spine in the tympanic bulla
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