10/26/2023
Today, the closest living relatives of cetaceans are the hippopotamuses; these share a semi-aquatic ancestor that branched off from other artiodactyls some 60 million years ago.[31] Around 40 million years ago, a common ancestor between the two branched off into cetacea and anthracotheres; anthracotheres became extinct at the end of the Pleistocene two-and-a-half million years ago, eventually leaving only one surviving lineage: the two species of hippo.[32][33]