For more than 100 million years, dinosaurs dominated the daylight hours, with warmth from the Sun enabling them to thrive. The night, therefore, might have provided small, mostly insect-eating mammals ...

When dinosaurs ruled the Earth, we tend to think of the mammals at the time — including our distant ancestors — as small and quivering in the shadows. "We've always had this picture of mammals as the ...

Some Mammal Traits Show Up a Lot Earlier and in Things That Weren’t Mammals at All. Lots of the traits we think of as defining us as mammals show up pretty early, during the time of the dinosaurs. And ...