Chinese paleontologists recently discovered a group of egg-stealing dragon hatching fossils in Cretaceous rocks in Ganzhou, Jiangxi Province, about 70 million years ago. The egg dragon is a small animal-footed sub-dinosaur. “Dinosaurs on nests are rare, and fossil embryos are rare. This is the first time a non-bird dinosaur has been found lying on an egg nest where embryos are preserved, a spectacular specimen. The paper’s first author, Dr. Bi Shundong, explained.
The fossil is made up of an incomplete skeleton, a large, possibly adult egg-stealing dragon, nested in a bird-like position in the nest of at least 24 eggs. At least seven of these eggs contained bones or parts of unhatched egg dragon embryos. The late stages of embryonic development and the closeness of adult egg-stealing dragons to eggs strongly suggest that adult egg-stealing dragons die during hatching, just like their modern bird cousins, unlike other dinosaurs, who simply lay eggs and leave.
“This discovery, which is essentially fossil behavior, is the rarest of dinosaurs.” Dr. Lamanna explains. “Although some adult egg dragons have been found in nests with eggs before, no embryos have ever been found in these eggs. In the new specimen, the baby dinosaur is almost ready to hatch, which tells us beyond a doubt that the dragon has been caring for its nest for quite some time. The dinosaur was a loving parent who eventually gave his life while feeding the cubs. ”
The team also performed oxygen isotope analysis, showing that the eggs hatched at bird-like temperatures, adding further support to the hypothesis that the prosthesis died during brooding. Also, although all embryos are well developed, some appear to be more mature than others, which in turn suggests that egg dragons in the same nest may hatch at slightly different times. The feature, known as ‘asynchronous hatching’, appears to have evolved independently among egg-stealing dragons and some modern birds.
Another interesting aspect of the new specimen is that the belly of an adult dinosaur retains a cobblestone. These are almost certainly “gastric stones” that were deliberately swallowed to help dinosaurs digest food. This is the first time that unquestioned “gastric stones” have been found in dragon thieves, so they may provide new insights into their diets.
“Incredibly, this fossil alone can capture so much biological information, ” Dr. Xu said. We will learn from this specimen for many years to come. ”