New fossil dolphin sheds light on history of Ganges dolphin

The discovery of a new fossil dolphin species - dating back to over 16 million years - is shedding new light on the history of the endangered Ganges and Indus river dolphins.
The unusual river dolphins, some of them known for their poor eyesight and side-swimming behaviour are all descendants of ocean-dwelling species, researchers said.
Until now, however, there has been no consensus about their relationships, and few specimens to help illuminate them, said researchers.
Researchers have described a new fossil dolphin species from the Miocene (dating to more than 16 million years) of the Pisco Basin, a desert on the coast of Peru.

It belongs to a rare extinct family of marine dolphins, the squalodelphinids, which are related to the endangered Ganges and Indus river dolphins living today.
The new specimens increase the known diversity of squalodelphinids and help shed light on their relationships.

River dolphins are a bizarre group of cetaceans (marine mammals) in that they reside in freshwater rivers and estuaries, though their ancestors were marine.
As a result of life in muddy river water, some are functionally blind and have very small dorsal fins.
Despite similar appearances, the South Asian river dolphins of the Ganges and Indus rivers (Platanista species) are only distantly related to other river dolphins of the Amazon and Yangtze rivers.

The new species, named Huaridelphis raimondii has been described from several well-preserved fossils.
"The quality of the fossils places these specimens as some of the best-preserved members of this rare family," said Olivier Lambert, of the Institut Royal des Sciences Naturelles de Belgique, lead author of the study.
Though the squalodelphinids have been known for some time, these small to medium size dolphins are rare in the fossil record, and were until now only found in a few localities.
The finding was published in the Journal of Vertebrate Paleontology.