Footprints preserved in mud were made by humans thousands of years before any people were thought to be in the Americas, a team confirms.

New research sheds light on two dinosaurs that once roamed what is now the eastern United States, including a cousin of the Tyrannosaurus rex.

The Clovis, some of North America's oldest inhabitants, probably only made stone tools for about 300 years, new research shows.

Researchers say DNA from stone tools from in a Mexican cave suggests humans first arrived in America about 15,000 years earlier than previously thought.

"More warming for trees could mean more stress, more tree death, and less capacity to slow global warming..."