Within 70-million-year-old rock deposits located in southern China's Jiangxi Province, researchers unearthed a preserved fossil of an oviraptorosaur crouched over a nest of 24 eggs, reports Alaa Elassar for CNN. Seven of the eggs were on the verge of hatching, making this the only fossil on record to have evidence of a dinosaur brooding on eggs that still had embryonic material inside and the first hard evidence that this species of dinosaur incubated their young, reports Laura Geggel for Live Science. The study was published this month in Science Bulletin.
"Dinosaurs preserved on their nests are rare, and so are fossil embryos. This is the first time a non-avian dinosaur has been found, sitting on a nest of eggs that preserve embryos, in a single spectacular specimen," says study co-author Shundong Bi, a paleontologist at Indiana University of Pennsylvania, in a statement.
Oviraptorosaurs, a type of theropod, were feathered dinosaurs with short, small parrot-like skulls. They thrived during the Cretaceous period between 65.5 million and 145.5 million years ago, Live Science reports. Many of their fossilized remains are found preserved in Ganzhou area of southern China. The recently recovered oviratorosaur fossil found alongside the Ganzhou railway station is missing its skull and part of its vertebrae, but it’s forearms, hind legs, and part of its tail were preserved. Even more remarkably, the nest of two dozen oval-shaped eggs underneath the adult dinosaur was also well-preserved. Each of the eggs measured 8.5 inches long and three inches across, Live Science reports. In seven of the eggs, researchers found bones and embryos of the baby dinos in curled positions, reports Carly Cassella for Science Alert.
The parent dinosaur was found sitting above the eggs with its forearms covering the nest. A behavior researchers suspect shows that the dinosaur was incubating the eggs for a long time, in part because the preserved eggs were almost ready to hatch, per Live Science.
"In the new specimen, the babies were almost ready to hatch, which tells us beyond a doubt that this oviraptorid had tended its nest for quite a long time," says study co-author and paleontologist Matt Lamanna in the statement. "This dinosaur was a caring parent that ultimately gave its life while nurturing its young."
To confirm the adult oviraptorosaurs was incubating the eggs, the researchers analyzed oxygen isotopes within the dinosaur embryos and fossilized eggshells, Live Science reports. The researchers found that the embryos were incubated at 86 to 100 degrees Fahrenheit, which is consistent with the parent dinosaurs body temperature, Science Alert reports. Adding a layer of evidence that the oviraptorid may have been sitting on the nest to keep the eggs warm, reports Live Science.
The fossilized find also contained gastroliths, or pebbles in the adult oviraptorosaur's abdominal region, revealing to researchers that these dinosaurs may have eaten stones to grind and digest food, reports CNN. This discovery is also the first time gastroliths were observed in an oviraptorid fossil.
"It's extraordinary to think how much biological information is captured in just this single fossil. We're going to be learning from this specimen for many years to come," said Xing Xu, a paleontologist at the Chinese Academy of Sciences, in a statement.