2004 Finds from Argentina
Chiappe, L. M., Codorniu, L., Grellet-Tinner, G., and Rivarola, D., 2004, Argentinian unhatched pterosaur fossil: Nature, vol.432, p. 571-572. (2 Dec 2004)
A pterosaur egg, MHIN-UNSL-GEO-v246, was discovered in the Lagarcito Formation in Argentina. This formation is well known for the Pterodaustro fossils and this egg was clearly a Pterodaustro egg. The embryo was intact and articulated.
The egg was from the Early Cretaceous deposits about 100 million years ago, and the proportions of the embryo closely matched those of known juvenile specimens. Measurements of the shell indicated a very thin (30μm) leathery shell which was long and oval in shape measuring 22mm by 66mm. The estimated embryo wingspan was 27cm. This egg has many differences from the Chinese finds earlier in the same year, but it does support the idea that all pterosaurs probably laid eggs.