Four-legged whale, new extinct species unearthed in Peru.
A new extinct species unearthed in Peru is the missing link in cetaceans that returned to the sea – a four-legged, hooved whale.
“The evolution of whales is perhaps the best-documented example of macroevolution that we have, with the group going from small, dog-sized, hoofed mammals to the giants of the ocean we know and love today,” said Travis Park, a postdoctoral fellow at the Natural History Museum in London, in a statement.
“However, despite having a good fossil record of the different stages involved, there are still questions remaining as to the routes that early whales took when they first spread around the world.”
We usually think of mammals as having evolved out of the sea and onto land, but for whales, that process ran backwards. The earliest known whale fossils from India and Pakistan show a species that transitioned back into the oceans in south Asia around 50 million years ago.
But this strange otterlike creature was found in Peru, lending credence to the theory that whales made their way westward across the Atlantic to reach North America around 40 million years ago.
According to a new study in Current Biology, microfossils located near the main find date the creature as 42.6 million years old.
“This is the first indisputable record of a quadrupedal whale skeleton for the whole Pacific Ocean, probably the oldest for the Americas and the most complete outside India and Pakistan,” said Dr Olivier Lambert, from the Royal Belgian Institute of Natural Sciences, co-author of the study.
Peregocetus pacificus, as it has been named, had four limbs, each ending in hooved toes, and a skeletal structure that suggests these legs could have supported the sizeable creature on land. However, its toes were webbed and its long tail looks like the tail of beaver, capable of undulating to propel it in the water.
“This partial skeleton represents a creature that could swim very well using its strong tail and webbed hands and feet, yet could still walk around on land on its hooved fingers and toes,” explained Travis.
“The features of the skeleton and its position in the whale family tree indicate that the most likely dispersal route of early whales to the Americas was from North Africa via the South Atlantic, where the distance between the African and South American continents was half what it is today.”