Even dinosaurs need a babysitter—or would that be dino-sitter? Researchers say a group of hatchlings found in a layer of rock might have been under the care of "a big brother or sister," the Philadelphia Inquirer reports. The 120-million-year-old Psittacosaurus bones were found in northeast China, the University of Pennsylvania reports. In a 2-foot-wide slab, 24 hatchlings were apparently overseen by a dinosaur about age 4 or 5, too young to be their mom or dad, LiveScience reports. Two of the young were entwined with the sitter's skull, suggesting intimacy when they all died.
While the finding suggests "post-hatchling cooperation," scientists can't be certain it's a nest of related dinosaurs. And it's possible the group was flung together by a volcanic flow and "may not have been directly interacting during life," says the study's author. However, there's some support for the theory in the behavior of birds (descended from dinosaurs) who help their parents with new babies instead of having their own; up to 8% of birds do this. The scientists will further study their dino-sitter theory by testing the babies' bones. If they are at the same point in development, they may be related. LiveScience has this gallery of the discovery. (These dinosaurs were much smaller than the gargantuan one newly uncovered in Patagonia.)