摘要
Pterosaurs are a group of flying reptiles which are the earliest vertebrates known to have evolved powerful flight capability. A recently discovered adult female pterosaur fossil preserved together with her egg provides the direct evidence of sex in pterosaurs and affords insights into the reproductive biology of these extinct fliers. The discovery helps us learn more about male Darwinopterus by comparing previously discovered fossils with the new female fossil. The new findings confirm that the males had relatively small pelvises and large cranial crests whereas the females had much larger pelvises but no cranial crests. Detailed studies of the fossilized egg imply that, as most researchers had previously suspected, the pterosaur’s reproductive strategies were not like those of birds but more like those of crocodiles or other reptiles. It is shown that the egg is relatively small in comparison with the pterosaur’s body and that it was likely soft and covered in a parchment-like shell, similar to the pterosaur embryo found before. The eggs could significantly conduct uptake of water after oviposition from their environment, and they probably increased in size and mass during this period. This means that the adult did not have to invest too much water in the egg, which could have been quite advantageous: Less material investmentin the egg and less mass to carry around during the production of the egg in the female’s body. This also suggests that Darwinopterus females buried their eggs like reptiles, paying little attention to them as they absorbed nutrients from the ground.
