The first three-dimensionally preserved pterosaur eggs have been discovered in the Turpan-Hami Basin, south of the Tian Shan Mountains in Xinjiang, China. The discovery was made by Xiaolin Wang of the Chinese Academy of Sciences' Institute of Vertebrate Paleontology and Paleoanthropology and colleagues from China and Brazil. The find was reported in the June 5, 2014, issue of the journal Current Biology.
The discovery includes five eggs that are three-dimensionally preserved and some that are almost complete. The eggs have a flexible structure with a thin exterior shell of calcium carbonate and an interior membrane that is soft and thick. This structure is similar to modern snake eggs. The eggs were buried to protect the eggs and to provide a constant temperature for incubation. Only four flattened pterosaur eggs have been discovered prior to this find. The eggs and fossils are 120 million years old. The new species was named Hamipterus tianshanensis.
The fossil site also produced some of the most complete three-dimensional pterosaur fossils ever known. The remains of male and female pterosaurs and their eggs were found in a single location. The researchers propose that the large number of animals preserved in the site and the extent of the detail that was preserved was the result of a large flood and the type of sediment at the site. Pterosaurs with wingspans ranging from one foot to 40 feet were found in the same location. The discovery indicates that pterosaurs lived in large groups like modern birds.
The discovery of so many animals in one location indicates that some form of gregarious behavior existed in a community of 40 male and female pterosaurs. The male and female fossils could be distinguished by the size and prominence of the head crest that is a distinctive structure in pterosaurs. The discovery of complete eggs indicates a probable maternal nurturing behavior that has never been seen in pterosaurs before.