Pterodaustro species
An un-hatched egg containing a juvenile Pterodaustro, from the Lagarcito Formation in Central Argentina. The lacustrine deposits are called the Loma del Pterodaustro and they are dated to about 100 million years ago.
Specimen MHIN-UNSL-GEO-V 246
Electron micrographs of the egg shell suggests a leathery shell. Ghosting of proteins can be interpreted within the shell structure.
Chiappe L.M., Codorniú L., Grellet-Tinner G. and Rivarola D.; 2004, Palaeobiology: Argentinian unhatched pterosaur fossil, Nature. 432, pp. 571-572 (2 Dec 2004)