Could aquatic mammals, such as whales, orcas, and bottlenose dolphins, ever evolve to live on land again? It seems the ...

About 250 million years ago, at the end of the Permian period, something killed some 90 percent of the planet's species. Less than 5 percent of the animal species in the seas survived. On land ...

Therapsids, the ancient relatives of mammals, once roamed Earth in great numbers during the middle to late Permian period.

In the Permian period before ... a dog-sized animal that looked like a cross between a pig and a lizard. These evolved land reptiles thrived during the periods after the Triassic – Jurassic ...