This artist's illustration shows Triceratops and juvenile tyrannosaurs facing off near the end of the Cretaceous Period 67 million years ago.
This mastodon fossil is on display at the American Museum of Natural History. A new study using mastodon DNA has suggested the animals migrated many times across North America during fluctuations in climate and environment.
A titanosaurian sauropod hatchling was found inside a dinosaur egg from 80 million years ago and its embryonic skull was still preserved.
This artist's illustration shows a young Purussaurus attacking a ground sloth in Amazonia 13 million years ago.
This bundle of bones is the torso of another marine reptile inside the stomach of a fossilized ichthyosaur from 240 million years ago.
Researchers uncovered the fossilized fragments of 200,000-year-old grass bedding in South Africa's Border Cave.