Pakicetus

Pakicetus (meaning 'whale from Pakistan') is an extinct genus of amphibious cetacean of the family Pakicetidae, which was endemic to South Asia during the Ypresian (early Eocene) period, about 50 million years ago. It was a wolf-like mammal, about long, and lived in and around water where it ate fish and other animals. The name Pakicetus comes from the fact that the first fossils of this extinct amphibious whale were discovered in Pakistan. The vast majority of paleontologists regard it as the most basal whale, representing a transitional stage between land mammals and whales. It belongs to the even-toed ungulates with the closest living non-cetacean relative being the hippopotamus.

==History of discovery== The first fossil is a skull fragment of P. inachus found in 1981 in Pakistan. Subsequent fossils of Pakicetus were also found in Pakistan, hence the generic name Pakicetus. The fossils were found in the Kuldana Formation west of Islamabad in northern Pakistan and were dated as early to early-middle Eocene in age. The discovery of Pakicetus played an important role in solidifying the inferences that revolved around the evolution of whales. The fossil indicated that whales swam up and down with their vertebral column, which caused their feet to move up and down like otters and their land movements were similar to sea lions; even their limbs protracted and retracted on land. In contrast, the origin of cetaceans, which includes whales, began as four-legged land animals who actively used locomotion and were great runners as a result.