Fossil shows mammal, dinosaur "locked in mortal combat"

A first-of-its-kind fossil of a mammal and a dinosaur from around 125 million years ago "locked in mortal combat" challenges the idea that dinosaurs ruled the land, researchers wrote in a study published Tuesday. 

The new fossil, discovered on May 16, 2012, in China's Liaoning Province, shows a mammal attacking a dinosaur about three times its size. The mammal, a carnivorous Repenomamus robustus, was the clear aggressor, researchers wrote in the journal Scientific Reports.

"The mammal died while biting two of the dinosaur's left anterior dorsal ribs; its mandible plunges downward into the indurated sediment to firmly clasp the bones," the study's authors wrote.