In China, scientists have identified the fossilized remains of a tiny dinosaur in the stomach of a mammal. Scientists say the animal’s last meal probably is the first proof that mammals hunted small dinosaurs some 130 million years ago.
It contradicts conventional evolutionary theory that early mammals couldn’t possibly attack and eat a dinosaur because they were timid, chipmunk-sized creatures that scurried in the looming shadow of the giant reptiles.
In this case, the mammal was about the size of a large cat, and the victim was a very young “parrot dinosaur” that measured about 5 inches long.
A second mammal fossil found at the same site claims the distinction of being the largest early mammal ever found. It’s about the size of a modern dog, a breathtaking 20 times larger than most mammals living in the early Cretaceous Period.
Considering the specimens in tandem, scientists suggest the period in which these animals lived may have been much different than is commonly understood as the Age of Dinosaurs — a time dominated by long-necked, 85-ton plant-eaters and the emergence of terrifying hunters with bladelike teeth and sickle claws.
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It appears that at least some smaller dinosaurs had to look over their shoulders for snarling, meat-eating mammals claiming the same turf.
“This new evidence gives us a drastically new picture,” said paleontologist Meng Jin of the American Museum of Natural History in New York City, a co-author of the study in Thursday’s issue of the journal Nature.
Other scientists who did not work on the bones described the discoveries as “exhilarating.”
“This size range really has surprised everybody,” said Zhexi Luo of the Carnegie Museum of Natural History in Pittsburgh, who digs in the same area of northeast China. “It dispels the conventional wisdom.”
The fossils were found more than two years ago by villagers in the rich fossil beds of Liaoning province. The specimens were taken to a Beijing lab, where they were cleaned and analyzed by Chinese and American scientists.
The dinosaur-eater belongs to a species called Repenomamus robustus, known previously from skull fragments. It has no modern relatives.
The squat, toothy specimen measures a little less than 2 feet long, and probably weighed about 15 pounds. On R. robustus’ left side and under the ribs in the area of its stomach are the fragmented remains of a very young Psittacosaurus.
This common, fast-moving plant-eater is known as the “parrot dinosaur” because it had a small head with a curved, horny beak. Its arms were much shorter than its legs. Adults grew to be 6 feet long, but the one that was devoured was just 5 inches.
The remains still are recognizable, indicating that R. robustus ripped its prey like a crocodile, but probably had not developed the ability to chew food like more advanced mammals.