In 2012, Lindsay Zanno was searching for dinosaur fossils in the hillsides of eastern Utah when she found a bone protruding from the hillside. Most of it was still wreathed in rock, but Zanno, who heads the paleontology division at the North Carolina Museum of Natural Sciences, could already tell that it was the limb of some two-legged meat eater. “That was a thrilling moment,” she says.
It took several years to fully free the bone, along with a few others, from the rock, and several more to work out that they were once the right leg of a tyrannosaur—a cousin of the famed Tyrannosaurus rex. But at just 170 pounds and six feet long from nose to tail, this new human-size dinosaur was much smaller than its more famous relative. Growth rings in the bones, much like those in a tree trunk, showed that the individual was at least seven years old and nearly mature. “It’s certainly not a very young individual of a very large species,” Zanno says. Instead, it was an adult—just a small one.
Zanno named it Moros, after the embodiment of impending doom in Greek mythology. It’s a rather dramatic name for such a diminutive dinosaur, but it’s apt considering the creature’s age. Moros lived 96 million years ago, preceding Tyrannosaurus by a good 30 million years. It was a miniature harbinger of the bone-crunching tyrants to come—impending doom, indeed. And its age and size offer important clues about one of the most dramatic plot twists in the dinosaur story.