Hunting for dinosaur fossils is often a game of luck, and a team of international scientists recently hit the jackpot. While digging in southern China's Jiangxi Province, paleontologists unearthed a fossilized oviraptorid nest consisting of the partial skeleton of a parent crouching over a clutch of 24 eggs. At least seven of those eggs contain the fossilized remains of dinosaur embryos.
The discovery was laid out in a study published online in the journal Science Bulletin late last year. The unique fossil dates back about 70 million years to the Cretaceous Period—the tail-end of the Dinosaur Age.
Fossilized dinosaur nests are rare to begin with, and researchers say this is the first known combination of eggs, embryos, and a mature dinosaur. A handful of the eggs in the newly uncovered fossil contain the partial skeletons of dinosaurs that were close to hatching. The nest also includes the bones of an adult dinosaur sitting on top of it. Scientists have identified the specimen as an oviraptorid—a group of beaked and feathered theropods.
The finding is a rare example of a fossil that exhibits animal behavior. Paleontologists still don't know if some dinosaurs incubated their eggs like birds, or laid them and immediately abandoned the nest. This fossilized snapshot of a dinosaur crouching over its nest sheds light on the mystery. Though this may be a case of the oviraptorid protecting the eggs rather than brooding over them, the fact that the embryos were so developed suggests the dinosaur had stayed close to the nest for a while.
The fossil has provided additional insights. Pebbles in the adult's abdomen point to the species swallowing rocks to help with digestion—something some modern birds do today. An analysis of oxygen isotopes in the fossil also shows that the internal temperatures of the adult and the embryos were similar, which is further evidence that oviraptorid parents incubated their eggs.
There's still a lot that remains unclear about the fossil, such as whether the adult was male or female (both sexes are known to incubate their young in the bird world). Scientists plan to keep studying the nest to learn more about parenting in the Cretaceous Period.