The Mesozoic Era extinctions formed the world as we know it today. Read about what caused them and which animals survived.

But the biggest development in the seas was the appearance of whales in the mid- to late Paleogene. The huge animals evolved from land mammals that took to the seas. Meanwhile, smaller reptiles ...

Modern birds, the distant relatives of those ancient giants, carry within their DNA the story of that cataclysmic event.

Small fossils show mammals moved to the ground before the dinosaurs vanished. New plants changed habitats, giving better food and shelter.

Dire wolves went extinct roughly 13,000 years ago ... Here's a look at what we know about the prehistoric species: Along with saber-toothed cats and enormous short-faced bears, dire wolves ...

Lyson at Denver Museum of Nature & Science in Denver, CO, and colleagues was titled, "Exceptional continental record of biotic recovery after the Cretaceous-Paleogene mass extinction." ...

It comes after the Jurassic Period and before the Paleogene - the first period of the ... released would have cooled the atmosphere. The Cretaceous extinction wiped out about 65% of all species. The ...

Along with sharks, many of these now-extinct species may have feasted on bottom-dwelling crustaceans ... layer of sediment or rock that geologists call the Cretaceous-Paleogene (K-Pg) boundary. The ...