New Delhi: A newly-described marine dolphin fossil found in Waitaki region of New Zealand has been linked to the endangered Ganges river dolphin, according to research published in Palaeontologia Electronica journal.

The dolphin group, Platanistoidea, to which the fossil species belonged, is extinct in the ocean and is now survived only by the endangered Ganges river dolphin and Indus river dolphin subspecies.

Professor Ewan Fordyce and his PhD student Yoshi Tanaka from the University of Otago, have formally described and named the new fossil species Otekaikea huata. The name is a reference to the marine limestone formation it was deposited in and the Maori word for spear.

“Our study is one of several showing that the South Asian river dolphin lineage was more diverse in the past. It is not clear why this lineage became extinct in the oceans, but it could have been due to long-term climate change and competition from later-evolving ocean dolphins," he says.

Otekaikea huata will be among only a few other dolphins known from about 22.5 to 24.5 million years ago. The fossil was discovered in the Hakataramea River valley. At that time, New Zealand was a cluster of small low islands with extensive shallow warm seas. According to researchers, the fossil dolphin’s skull was about 80 cm long and its body around 2.6 metres.

“The fossil has a surprisingly long projecting tusk that became broken in life, but whether this was from fighting or feeding is uncertain. It’s likely that it had four or more tusks in life, but these others weren’t preserved," Fordyce said in a press release.