This prehistoric quadruped discovered on the coast of Peru was similar to a modern-day otter or beaver — except it was 13 ...

Certain skeletal features of archaic whales, particularly their large, triangular cheek teeth, strongly resembled those of mesonychids, a group of hoofed Eocene carnivores. (The massive ...

The first was right at the beginning of whale evolution, just shy of 50 million years ago, when the archaeocetes—the ancestors of modern cetaceans, which emerged in the Eocene Epoch—were first ...