The discovery of Sarahsaurus aurifontanalis, which roamed North America about 190 million years ago, also boosts the idea that at least some dinosaurs became masters of their domain less by dominance than by opportunistic behavior and a bit of good luck.
A remarkably complete Sarahsaurus skeleton, found in Arizona, shows that the early Jurassic herbivore was, at 14 feet (4.3 meters) long and 250 pounds (113 kilograms), smaller than its enormous sauropod cousins such as Apatosaurus, which arose later. (See a sauropod picture.)
Like the sauropods—the largest animals to walk Earth—Sarahsaurus featured a long neck and small head. But the newly identified creature also boasted strong teeth and an unusual clawed hand, that, while only human size, was clearly built for enormous power and leverage, according to paleontologists.
“The dogma is that these animals were herbivores, but these hands and massive claws reopen the door to what they might have been doing with them,” said study leader Tim Rowe, a paleontologist at the University of Texas.