Fossils discovered of a dinosaur that died while hatching its eggs

Oviraptorid brooding its nest of eggsAn article published in the journal “Science Bulletin” reports the discovery of fossils of a species of feathered dinosaur attributed to the oviraptorid family that include a partial skeleton of an adult that was brooding a group of 24 eggs, some of which were broken and showed bones still in their embryonic state. A team of researchers conducted the first study of these fossils dating back to about 70 million years ago, during the Cretaceous period, discovered in the Nanxiong Formation, near the city of Ganzhou, China. This is the first discovery of a non-avian dinosaur while it was brooding a nest with eggs that preserved their embryos.

Oviraptorids (Oviraptoridae) are a family of dinosaurs that lived mainly in present-day China, where almost all the fossil finds occurred. In recent decades, many oviraptorid fossils have been discovered, all of which probably had plumage. One consequence is that the taxonomic classification within this family often changes and becomes a source of discussion among paleontologists.

The skeleton attributed to the oviraptorid family object of this study is partial, a common problem in the field of paleontology. Despite this, it’s very interesting because it was discovered together with a group of 24 eggs while it was hatching them. Oviraptorids were related to birds, so it’s not surprising that they hatched eggs, but such a find may offer new insights into the similarities and differences between birds and their extinct cousins.

The top image (Courtesy Bi et al. All rights reserved) shows the oviraptorid fossils (a), a drawing showing the bones, eggs, and gastroliths (b), and a reconstruction of this dinosaur with the available bones drawn in white.

The characteristics of the fossil eggs showed that the researchers were right to be interested in them. Isotope analyzes revealed that the eggs were incubating at temperatures typical of birds’ hatching. One discovery concerns the embryos’ level of development, which is not the same for all of them. The so-called asynchronous hatching exists in some modern bird species and appears to have evolved independently in these distant relatives.

The adult specimen was discovered along with some gastroliths in its abdominal region. These stones were swallowed by various dinosaurs to grind hard plants and are now used by various species of herbivorous birds and other animals. Again, this is the first finding in an oviraptorid and indicates that it was a herbivore.

This oviraptorid exhibits interesting similarities with birds which confirm the complexity of the evolution of a large group of dinosaurs. Recently, many researchers have been focusing on the evolution of flight, but discoveries such as these fossils with an adult hatching its eggs offer information on their reproduction as well. For this reason, they will certainly be the subject of further in-depth studies.

Artist's illustration of oviraptorid brooding its nest of eggs (Image courtesy Zhao Chuang)
Artist’s illustration of oviraptorid brooding its nest of eggs (Image courtesy Zhao Chuang)

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