Varricchio and his colleagues analyzed a two-foot wide specimen of red-grey mudstone collected from the Lower Cretaceous Yixian Formation, an area in Liaoning, China, that is famous for providing well-preserved dinosaur and bird fossils. The remains are of a type of dinosaur known as Psittacosaurus, a plant-eating creature that grew to be about the same size as a midsize dog. The posture of the skeletons--all the creatures were upright with their legs tucked beneath them--suggests that the animals were rapidly entombed while still alive, the authors note. Just how the creatures perished remains unclear, but a collapsing burrow, flooding or a covering of volcanic debris could be to blame.
From the size of the young as well as the density of the bone remains, the researchers infer that the parental care was extensive. Today's archosaurs--crocodilians and birds--are model parents, providing warmth, food and shelter, but whether the traits evolved independently is still unclear. The authors caution that more finds supporting the theory of doting dino dads and moms are required to determine if it's indeed a shared ancestral characteristic.