New amphibious whale fossil
A striking fourlegged hooved amphibious whale is described in the April 2019 issue of the science journal Current
Biology. Based on an unusually complete fossilised skeleton from the midEocene Epoch of Peru, and dated at 42.6 million years old, it is half tetrapod land mammal and half aquatic sea creature. The newly found whale thus resembles an otter in having feet that functioned well both for walking on land and for swimming. Named
Peregocetus pacificus by Olivier Lambert and colleagues, it is the oldest whale skeleton found in the New World (i.e., the western hemisphere, comprising North and South America and the Pacific
Ocean). The authors think it had webbed feet and long toes, enabling it to dogpaddle while also using its tail as a paddle, as otters and beavers do today.
The toes had small hooves while the legs and hips were strong, enabling the early whale to walk well on land, but it was already better adapted to swimming.
Whales began as landdwelling tetrapod mammals and gradually became more and more adapted to living in water. The first amphibious whales evolved over 50 million years ago near what is now India and Pakistan. The age of the new whale is consistent with whales crossing the South Atlantic Ocean and around South America to the Pacific Ocean in their first 10 million years. However, note that between now and the time when this fossil whale was alive, continuing plate tectonics have doubled the distance between Africa and North and South America.
(See: Lambert, O. et al. 2019. An amphibious whale from the middle Eocene of Peru reveals early South Pacific dispersal of quadrupedal cetaceans. Current
Biology 29, 18, April 22, 2019.)