Hard evidence from soft fossil eggs

Hard evidence from soft fossil eggs

Some dinosaurs laid soft-shelled eggs

New discoveries of intriguing fossilized soft-shelled eggs challenge the long-held idea that dinosaurs laid hard-shelled eggs whereas ancient marine reptiles gave birth to live young. Researchers analysed eggs containing embryos of the sauropod-like dinosaur Mussaurus from the Late Triassic, and the horned dinosaur Protoceratops, from the Late Cretaceous. The findings hint that the earliest eggs laid by dinosaurs were actually soft-shelled and did not tend to survive in the fossil record because of their fragility.

Separately, researchers report the discovery of a soft-shelled fossil egg dubbed Antarcticoolithus about the size of a football — among the largest eggs ever recorded — from a mysterious Cretaceous creature. It might have been laid by a giant marine reptile — or, given the other findings, even by a dinosaur.

Nature News & Views | 6 min readReference: Nature paper 1 & Nature paper 2