|Female Darwinopterus with egg (Lu et al., 2011)|
The researchers believe the 3-foot long flying reptilian was caught in a storm which may have broken here wing and washed her into a lake where she died, with the pressure of the mud expelling her egg.
David Unwin (University of Leicester) whose analysis of the fossil was published in Science yesterday describes it as a "tragedy" for the pterosaur, but that the find could answer some important questions about differences in gender in the pterosaur.
The 160 million years old fossil was identified as a Darwinopterus, a type of pterosaur (flying reptile) which lived in the middle of the Jurassic.
The egg appears to have been soft, inficating it would have been buried and left after laying rather than tended to constantly like a bird's egg.
The bird lacks a bony headcrest and Unwin believes that this, along with an enlarged pelvis are defining characteristics of a female pterosaur.
Unlike dinosaurs, whose features are preserved in modern day birds, pterosaurs were an 'evolutionary dead end'.