Madrid. Palentologists have recovered in southern China the remains of the world’s first dinosaur specimen that has been found sitting in a nest of eggs with fossilized young.
It is the fossil of an ovirraptorsaurus, a group of bird-like theropod dinosaurs that thrived during the Cretaceous, the third and last period of the Mesozoic Era (Age of Dinosaurs) that spanned from 145 to 66 million years ago.
It was recovered from rocks from the Upper Cretaceous, some 70 million years old, in the city of Ganzhou, in the province of Jiangxi.
“Dinosaurs preserved in their nests are rare, as are fossil embryos. It is the first time that a non-avian dinosaur has been found, sitting in a nest of eggs that preserve embryos, in a single spectacular specimen, ”explained Shundong Bi, from Yunnan University and lead author, cited by Science China Press.
The fossil, described in Science Bulletin, consists of the incomplete skeleton of a large, presumably adult ovirraptor, crouching in a bird-hatching posture over a clutch of about 24 eggs. At least seven have bones or partial skeletons of ovirraptorid embryos without hatching inside.
The rarest of finds
The late stage of development of the embryos and the proximity of the adult to them strongly suggests that the latter died in the act of hatching the nest, like its modern bird cousins, rather than laying eggs or simply protecting its crocodile-style nest, as has sometimes been proposed for the few other ovirraptorid skeletons that have been found above nests.
“This discovery, essentially fossilized behavior, is the rarest of the rare in dinosaurs,” explained Matthew C. Lamanna, a co-author of the study and a member of the Pittsburg Museum of Natural History. “Although some adult ovirraptorids have been found in nests before, embryos have never been found inside those eggs. In the new specimen, the young were almost ready to hatch, indicating without a doubt that this oviraptorid had been laying its nest for quite some time. This dinosaur was a loving father who finally gave his life while feeding his young. “
The team also carried out oxygen isotope analyzes indicating that the eggs were incubated at high temperatures, similar to those of birds, further supporting the hypothesis that the adult died in the act of hatching. Furthermore, although all the embryos were well developed, some appear to have been more mature than others, which in turn suggests that they may have hatched at slightly different times. This feature, known as asynchronous hatching, appears to have evolved independently in ovirraptorids and some modern birds.