Pakicetus, extinct genus of early cetacean mammals known from fossils discovered in 48.5-million-year-old river delta deposits in present-day Pakistan. Pakicetus is one of the earliest whales and the first cetacean discovered with functional legs. In addition, it still retained many other features
Want to blow your mind? Look at the evolutionary history of whales. Whales are mammals, not fish. As such their ancestors were land animals, specifically the Pakicetus.