Like turtles, some dinosaurs laid soft-shell eggs


„We always thought that the ancestral dinosaur egg had a hard shell,“ said Mark Norell of the American Museum of Natural History in New York. But the research he has conducted, which is the subject of a publication in the prestigious journal Nature, contradicts this opinion, which had hitherto been largely in the majority among paleontologists.

Everything started from an observation: fossilized dinosaur eggs have been discovered, in large numbers, on almost the entire planet for decades. But for the most part, they only belong to three groups of dinosaurs: theropods which include current birds, hadrosaurs or duckbill dinosaurs, and long-necked Cretaceous sauropods. For the others, and in particular, for the ceratopsians who group together horned dinosaurs like the triceratops of which thousands of skeletal remains have been discovered, there are practically no eggs. A hypothesis to explain this absence then began to emerge: if the eggs did not fossilize it is undoubted that their shells were soft and therefore much less resistant to time. It only remained to prove it.

It was not easy, but the scientists still managed to find fossils of interest for their study. Two „nests“ containing eggs with embryos inside. The first belongs to a Protoceratops, a small dinosaur the size of a sheep, a herbivore that lived in Mongolia, 75 to 71 million years ago. And the second to a Mussaurus, a much older dinosaur, 227 to 208.5 million years old, from the sauropodomorph suborder which could reach 6 meters long, discovered in Argentina.