The finding, which appears in the journal Science, provides evidence for what scientists had previously hypothesized: that female pterosaurs had larger hips than males and no crest on the skull. Male pterosaurs had large crests.

The egg appears to be soft-shelled, more similar to those of crocodiles than those of birds. This implies that, like crocodiles and other reptiles, pterosaurs probably buried their eggs, rather than incubating them by sitting on them, as birds do.

Dr. Unwin said that the fossil has provided a good preliminary picture of pterosaur biology.

“What we now need to do,” he said, “is to look at lots of pterosaurs and look at other things such as size: Were males typically bigger or smaller than females? And other really fundamental kinds of things that we know for living species, we can now look at in pterosaurs.”