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Dinosaur-Eating Mammal Found

Posted on: Thursday, 13 January 2005, 18:00 CST

Scientists working in a rich fossil field in China unearthed the skeleton of an opossum-sized mammal whose stomach contained the remains of a baby dinosaur, a startling finding that sheds new light on the struggle for survival 130 million years ago.

Until now, science viewed the first mammals solely as tiny shrewlike creatures that lived in the shadow of the dinosaurs. By day, these early mammals hid in caves; under cover of darkness they scurried forth to hunt insects.

Only when the dinosaurs died off was it safe for the original mammals to go outdoors, whereupon they enjoyed an explosion of biodiversity that ultimately advanced to primates and human beings, or so most scientists believed.

The new discovery, reported Wednesday in the British journal Nature, challenges much of that. It provides the first direct evidence that some primitive mammals were carnivores that competed with the dinosaurs for food and land.

The dinosaur-eating mammal belonged to a species dubbed Repenomamus robustus. But it was a runt compared with a nearby fossil of an even larger new species the size of a 30-pound dog, Repenomamus giganticus. Both went extinct long ago.

R. giganticus is the largest known mammal with fairly complete fossil remains ever found from the Mesozoic era, 280 to 65 million years ago, when dinosaurs and other animals faced extinction.

"We think these fossils are pretty cool. Mammals are never in the spotlight of Mesozoic life. Dinosaurs are the big guys," said team leader Jin Meng, curator in the division of paleontology at the American Museum of Natural History in New York.

Source: Advocate; Baton Rouge, La.

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