The fossil of a dinosaur sitting on a nest of eggs with embryos inside was unearthed in a unique discovery that sheds light on how the creatures hatch their young.
The skeletal remains of an Oviraptorosaurus – a bird-like beast that roamed Earth more than 66 million years ago – were found in 70-million-year-old rocks excavated in Ganzhou, China, according to a report published in the journal Science Bulletin. .
The partially preserved feathered dinosaur had hatched a nest of 24 eggs, seven of which contained the skeletal remains of developing babies, paleontologists said in the report.
The groundbreaking finding is a sign that oviraptorosaurs sat on nests like their current avian cousins, rather than guarding clutches of eggs like alligators and other reptiles.
“This kind of discovery – essentially petrified behavior – is the rarest of the rare in dinosaurs,” said Matthew Lamanna of the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania, who wrote the study in a press release. “Although a few adult oviraptorids have been found on nests of their eggs before, no embryos have ever been found in those eggs.”
Scientists ruled out the possibility that the dinosaur had died while laying eggs due to the late stage of the embryos. They also examined the eggs with an oxygen isotope, which showed that they hatched at high temperatures, just like young birds that have yet to hatch.
Researchers also found that the embryos were in different stages of development, suggesting the presence of “asynchronous hatching” – an incubation method that may have evolved over time in oviraptorid dinosaurs and some birds.
“This dinosaur was a caring parent who eventually gave his life while nursing its young,” Lamanna concluded in the report.
Other researchers called the fossil find a breakthrough of Jurassic proportions.
“It is extraordinary to consider how much biological information has been captured in just this one fossil,” said vertebrate paleontology Xing Xu of the Chinese Academy of Sciences in Beijing in a press release. “We will learn from this specimen for many years to come.”
The report does not mention the size of the fossilized dinosaur or its eggs, but oviraptorosaurs ranged in size from a turkey to larger than an elephant.