So far, the team has located three of these death pits, each a diorama of a desperate struggle. One features a crocodilian huddled next to a small ceratosaur; another contains three headless ceratosaurs, possibly decapitated by predators big enough to avoid getting stuck in the trap. The most spectacular of the pits contains the remains of a 170-pound tyrannosauroid. Xu named it Guanlong, Chinese for “crowned dragon,” a reference to a crest that stretched from its snout to the back of its head. Its discovery sent rumblings through the paleontology community, because it represents the earliest and most primitive of the infamous “tyrant lizards,” a family of powerful predators that culminated more than 90 million years later with the most fearsome of them all, Tyrannosaurus rex.
“What’s striking about this find,” says Thomas Holtz, a tyrannosaur expert at the University of Maryland, “is the revelation that T. rex, the king of the tyrant lizards, comes from such humble origins. Most people think of tyrannosaurs as dominant predators, but that was toward the end of their line. For most of their history, they probably were the jackals of their day.”
To its surprise, the team found a second, smaller Guanlong beneath the first, leading to speculation that an adult had gone after a youngster trapped in the pit. It’s possible, says Holtz. “We have numerous tyrannosaur skulls that bear bite marks from other tyrannosaurs.”
Clark and Xu are eager to explore new parts of the Junggar Basin later this summer. “There’s still so much to find,” says Clark. “I can’t wait to see what turns up next.”