A mysterious "runner" dinosaur, only about the size of a dog, scurried around the ancient floodplains of what is now Colorado around 150 million years ago, a new study finds. The two-legged herbivore, ...

It was a cloudy morning in southeast Mongolia. Paleontologist Chinzorig Tsogtbaatar and several colleagues set out by foot from their campsite to a rocky outcrop dating back some 110 million years to ...