Missing Link Ancestor of Whales Discovered

Fossil remains found in the Kashmir region of India suggest the fox-sized mammal deer-like animal that lived 48 million years ago is the long-sought land-based ancestor of the planet's cetaceans: whales, dolphins and porpoises.

Whales are known to be descended from land-dwellers but the "missing link" has been a mystery until now. Research in Nature suggests that although the animal, Indonyus, as it is known, looks nothing like the whales of today,it  lived mainly on land but dived into water to escape predators. Indonyus belongs to an ancient order of mammals that had two or four toes on each foot. Modern day representatives of the group include camels, pigs, and hippopotamuses.

The structures of the fossil skull and ear are similar to those of early whales, and like other animals that spend a lot of time in water, it had thickened bones that provided ballast to keep its feet anchored in shallow water.

"We've found the closest extinct relative to whales and it is closer than any living relative," said study leader Professor Hans Thewissen of the Department of Anatomy at Northeastern Ohio Universities College of Medicine in Ohio, US.

DNA studies show that hippos are in fact closely related to modern whales. They do not appear in the fossil record until about 15 million years ago, some 35 million years after the cetaceans originated in south Asia.

This led Professor Thewissen and his team to search for an older land-based ancestor that would fill in some of the gaps in our knowledge of the whale's dramatic evolutionary journey from land to sea. The stable-oxygen-isotope composition of its teeth suggest that the animal spent much of its time in water.
Some reseachers have assumed that the ancestor of whales first took to the water to feed on fish but the latest evidence suggests otherwise.

"The new model is that initially they were small deer-like animals that took to the water to avoid predators," Professor Thewissen told BBC News. "Then they started living in water, and then they switched their diet to become carnivores."

Posted by Casey Kazan.

Story link:

http://news.bbc.co.uk/2/hi/science/nature/7150627.stm

Comments

[Scott]

"and then they switched their diet and became carnivores" Hmmm...I have some major problems with that. Have you ever tried to force a plant eater to "switch" its diet? No......trust me.....it will starve because why?.....it does not recognize flesh as food. It sounds so flippant and easy the way this article is written. I think not. Until more fossil
evidence is produced, I think they are barking up the wrong ancestor.

[www.google.com/accounts/o8/id?id=AItOawlrwJwUAV5YrFhMQ2fDc2Q2wyxbeiI0P24]

It's absolutely possible! Obviously, it took many thousands of years for this to take place, but organisms are never confined to one or the other indefinitely. Otherwise, we wouldn't have omnivores period. And there are more omnivorous species on this planet at this point than ever before in Earth's history. It seems to be an evolutionary destination for all creatures, in fact. All it takes is the development of a few extra biological mechanisms to be able to handle both plants and animals in a diet, so it's really not that far-fetched.