Every 27 million years, there is a much higher likelihood of a mass extinction. Some astronomers have proposed that these extinctions are caused by a small comet-disturbing star orbiting our sun, the so-called Nemesis hypothesis.
The Washington Monument looms behind a flower bed.
A sperm whale that measured up to 59 feet long and lived some 12 million to 13 million years ago used to hunt smaller whales. The species is named for Herman Melville, author of 'Moby-Dick.'
A new iPhone app just released by the Smithsonian National Museum of Natural History shows what you would look like if you were a Neanderthal with an iPhone.
The fossil, nearly 2 million years old, 'may make a very good candidate' to be a new species of early human. Found in South Africa, it has a unique combination of ape-like and human features.
Five-year-old Lenny Popova, of Arlington, Va. inspects the teeth of a Tyrannosaurus rex at the National Zoo, in October 2000. The Tyrannosaurus, meaning 'tyrant lizard' lived in Western North America during the last part of the Cretaceous Period, about 68 to 65 million years ago.
Two findings this week boost the link between birds and dinosaurs. They include the discovery of a bird-like dinosaur and a fossil analysis that suggests some dinosaurs sported colored feathers.
Two new studies challenge the current theory.