Preserved pterosaur eggs hint at reptile’s social life

A vast graveyard of eggs and bones suggests that a newly discovered flying reptile species, Hamipterus tianshanensis, probably nested in groups.

The find cracks open an old question about pterosaur life — whether the animals flocked together or flew solo. Pterosaurs’ fragile skeletons make finding intact bones tough. Fossil eggs are even rarer. Until now, scientists had found only four isolated, squished ones. So the lifestyle of the winged animals’ was mostly a mystery.

In northwestern China, paleontologist Xiaolin Wang of the Chinese Academy of Sciences in Beijing and colleagues unearthed the fossils of about 40 pterosaurs, narrow-skulled creatures spouting Mohawk-like crests. The researchers also found five complete eggs. The eggs — Grade A compared with the flattened previous finds — have kept most of their original 3-D shape, the researchers report in the June 16 Current Biology.

About the size of skinny chicken eggs, the pterosaur eggs probably had a cushiony membrane covered with a thin shell, like a gummy bear with an M&M coating. Because the fossil eggs were found scrambled among the bones of so many pterosaurs, Wang and colleagues think the animals were a social bunch. Instead of ranging freely by themselves, the pterosaurs probably laid eggs together.