The world’s first preserved dinosaur sitting on a nest of eggs with fossilized babies

The fossil in question is that of an oviraptorosaur, a group of bird-like theropod dinosaurs that thrived during the Cretaceous, the third and final period of the Mesozoic (commonly known as the “ Age of Dinosaurs ”), which spanned from 145 to 66 million years. ago. The new specimen was recovered from the upper Cretaceous rocks, some 70 million years old, in the city of Ganzhou in Jiangxi province in southern China.

“Dinosaurs kept on their nests are rare, as are fossil embryos. This is the first time that a non-avian dinosaur has been found sitting on a nest of eggs containing embryos in a single spectacular specimen,” explains Dr. Shundong explains. Bi.

The fossil consists of an incomplete skeleton of a large, presumably adult oviraptorid crouched in a birdlike brooding position over a clutch of at least 24 eggs. At least seven of these eggs store bones or partial skeletons of unshaded oviraptoride embryos inside. The late stage of development of the embryos and the adult’s proximity to the eggs strongly suggests that the latter died while hatching from its nest, like its modern cousins, rather than laying its eggs or simply guarding its nesting crocodile. style, as has sometimes been suggested for the few other oviraptorid skeletons found on top of nests.

“This kind of discovery, essentially fossilized behavior, is the rarest of the rare in dinosaurs,” explains Dr. Lamanna explains. Although a few adult oviraptorids have previously been found on nests of their eggs, no embryos have ever been found in those eggs. for quite a long time. This dinosaur was a caring parent who eventually gave his life while nursing his young. “

The team also performed oxygen isotope analyzes indicating that the eggs were incubated at high, bird-like temperatures, further supporting the hypothesis that the adult perished while incubating its nest. In addition, although all embryos were well developed, some appear to have been more mature than others, which in turn suggests that oviraptorid eggs in the same clutch may have hatched at slightly different times. This trait, known as asynchronous hatching, appears to have evolved independently in oviraptorids and some modern birds.

Another interesting aspect of the new oviraptoride specimen is that the adult retains a cluster of pebbles in its abdominal area. These are almost certainly gastroliths, or ‘stomach stones’, rocks that would have been deliberately swallowed to help the dinosaur digest its food. This is the first time that gastroliths have undoubtedly been found in an oviraptorid, and as such, these stones may provide new insights into the nutrition of these animals.

Dr. Xu says, “It is extraordinary to consider how much biological information is contained only in this one fossil. We will learn from this specimen for many years to come.”

See the article:

Bi, S., Amiot, R., de Fabrègues, CP, Pittman, M., Lamanna, MC, Yu, Y., Yu, C., Yang, T., Zhang, S., Zhao, Q. and Xu , X., 2020. An oviraptoride stored on top of an embryo-bearing egg clutch sheds light on the reproductive biology of non-avialan theropod dinosaurs. Science Bulletin2020, https: /doi.org /10.1016 /j.scib.2020.12.018