An egg-adult association, gender, and reproduction in pterosaurs

A sexually mature individual of Darwinopterus preserved together with an egg from the Jurassic of China provides the first direct evidence of gender in pterosaurs and unique insights into the reproductive biology of these extinct fliers. The new find and several other examples of Darwinopterus demonstrate that males of this pterosaur had relatively small pelves and a large cranial crest, while females had relatively large pelves and no crest. The egg mass/adult mass index is relatively low, as in extant reptiles, and comparable to values for squamates. A parchment-like eggshell points to burial and significant uptake of water post oviposition. This “low investment strategy” contradicts the widespread assumption that reproduction in pterosaurs was like that of birds and shows that it was essentially reptilian.