Although they came into their own only after the extinction of the dinosaurs some 65 million years ago, mammals had maintained a low-profile existence for some 150 million years before that.

The new research is the first to look back at early mammals in full color. Using advanced fossil imaging methods and a ...

Faced with an evolving group of competing organisms -- the mammals -- perhaps dinosaurs were driven to extinction by competition. Packs of small mammals would have competed with dinosaurs for food.