Kunming (China). Fossil clutches and embryos discovered by paleontologists during excavations show that most dinosaurs laid eggs . A slightly increased development temperature of the eggs, which was detected by isotope analysis, indicates that the eggs have hatched. For a long time, however, science was unable to produce any proof of this .
A team led by Shundong Bi from Yunnan University has now discovered a fossil nest with eggs that were hatched by an adult dinosaur in the southern Chinese city of Ganzhou. The nest dates from the late Cretaceous period and is around 70 million years old.
Predatory dinosaur hatches eggs
According to the publication in the Science Bulletin , the fossils come from a predatory dinosaur belonging to the group of oviraptorosaurs. The adult animal is completely preserved except for the missing skull and lies in a hunched position over the eggs. The nest contains over 20 eggs, most of which are not damaged. What is surprising about the discovery is that there are still unhatched embryos in at least seven of the eggs.
Shundong Bi : “Dinosaurs on their nests are just as rare as fossilized dinosaur embryos. This is the first time that both have come together in a single, spectacular find: a dinosaur sitting on its nest with preserved embryos in the egg. “
Eggs destroyed or empty in other finds
In the case of fossils previously found in the vicinity of nests, however, it was unclear whether it was a parent animal or a nest predator because the excavated eggs were either destroyed or empty.
The fact that an oviraptorosaur has now been found with eggs that have not yet hatched, some of which were already well developed, proves, according to the researchers, that it is a breeding parent animal. However, due to the advanced development of the young animals, death while laying eggs is unlikely.
Oxygen isotopes confirm breeding behavior
Instead, the explorers assume that the dinosaur was caught by surprise while it was breeding and died. The excavation thus proves a real breeding behavior that resembles the behavior of today’s birds .
Matthew Lamanna , Carnegie Museum of Natural History: “In our find, the young were almost ready to hatch. This tells us without a doubt that this Oviraptorid has been caring for its clutch for a long time. This dinosaur was a caring parent who ultimately gave their life while taking care of their offspring. This type of discovery is the rarest of all rare dinosaur finds – in principle we are seeing fossilized behavior here. “
A closer analysis of the eggs also confirms the breeding behavior of the adult dinosaur. The oxygen isotopes in the fossil embryos show a development at a temperature between 30 and 38 degrees Celsius, i.e. well above the ambient temperature at that time, which also speaks strongly in favor of the eggs hatching.