http://www.sciencemag.org/content/331/6015/321.full Junchang Lü, David M. Unwin, D. Charles Deeming, Xingsheng Jin, Yongqing Liu and Qiang Ji An Egg-Adult Association, Gender, and Reproduction in Pterosaurs Science 21 January 2011: Vol. 331 no. 6015 pp. 321-324 DOI: 10.1126/science.1197323 Abstract: A sexually mature individual of Darwinopterus preserved together with an egg from the Jurassic of China provides direct evidence of gender in pterosaurs and insights into the reproductive biology of these extinct fliers. This new find and several other examples of Darwinopterus demonstrate that males of this pterosaur had a relatively small pelvis and a large cranial crest, whereas females had a relatively large pelvis and no crest. The ratio of egg mass to adult mass is relatively low, as in extant reptiles, and is comparable to values for squamates. A parchment-like eggshell points to burial and significant uptake of water after oviposition. This evidence for low parental investment contradicts the widespread assumption that reproduction in pterosaurs was like that of birds and shows that it was essentially like that of reptiles. --Mikko