It's still a mystery what killed them. But whether it was toxic gases or a flooded burrow, a group of fossils shows that an adult dinosaur died together with 34 hatchlings. The find offers new evidence about how dinosaurs may have looked after their young charges.
Paleontologists have found powerful evidence before that dinosaurs protected their nests. Consider, for example, the skeleton of a carnivorous Oviraptor preserved with its arms stretched over its eggs. They've also dug up signs that juveniles hung out with adults. But although bones of immature duck-billed dinosaurs have been uncovered in nests, hatchlings hadn't been found in the company of adults.
The new specimen, described in this week's issue of Nature, contains the partial skeleton of an adult Psittacosaurus, a herbivorous dinosaur with a parrotlike beak. Surrounding it are 34 young, each between 3 and 3.4 centimeters long. Whereas most fossils of dinosaurs show the animals lying on their sides as if dead, these were found flat on their bellies with their heads slightly raised. "It almost seems like they were alive when buried," says paleontologist David Varricchio of Montana State University, Bozeman. One possibility is that volcanic gases or ash killed the animals; the part of China where the fossils were found, Liaoning Province, saw frequent eruptions during the Early Cretaceous period 120 million years ago.In any case, Varricchio, Jinyuan Liu of the Dalian Natural History Museum in China, and their colleagues are more interested in what the fossils say about the Psittacosaurus's life. For example, this adult may have been protecting several broods, says David Weishampel, a paleontologist at the Johns Hopkins University School of Medicine in Baltimore, Maryland, who notes that it's hard to imagine one female laying 34 eggs. The "amazing" new fossil, he says, "tells a story of parental care that is absolutely clear."
Dalian Natural History Museum