A newly discovered dinosaur from China that had an elaborate head crest and other birdlike features is the oldest known ancestor of Tyrannosaurus rex, scientists say.
"I wish we hadn't had to do it," said NASA's administrator in response to criticism of the plan to redirect funds from scientific exploration to human spaceflight.
A study of three ancient communities sheds light on the historical differences between cultures around the globe, as well as how and why people learned to work together.
