The first animals that were ancestors of whales are thought to have been deer-like mammals that could walk on land about 50 million years ago, and over time, they evolved into the ocean dwellers we're familiar with today. The now-extinct animals that were in the middle of that transition from land-based to sea-based animals are called Protocetidae. Reporting in the Proceedings of the Royal Society B, scientists excavating rocks from the Fayum Depression in the Western Desert of Egypt have discovered a fossil from an amphibious whale that lived an estimated 43 million years ago. This creature, which was belongs to the Protocetidae group, could swim in water and walk on land.
The fossil indicates that the animal, now named Phiomicetus anubis, weighed about 600 kilograms (about 1,300 pounds) and was three meters (10 feet) long. Its jaws appear to have been powerful, and the animal probably used them to consume prey. The researchers suggested that it may have been a major predator in its environment.
The rocks in the Fayum Depression represent about 12 million years of history, and discoveries there "range from semi-aquatic crocodile-like whales to giant fully aquatic whales," said study co-author Mohamed Sameh of the Egyptian Environmental Affairs Agency.
This is the first time a specimen from this species has been found, and this is the oldest protocetid whale found in Africa. The research has revealed new details about the transition of whales from amphibious to totally aquatic.
Scientists also discovered an amphibious whale fossil in Peru in 2011. That animal had four legs, hooves and webbed feet.