Comparison of water vapor conductance in a titanosaur egg from the Upper Cretaceous of Argentina and a Megaloolithus siruguei egg from Spain

Abstract

Abstract We calculated water vapor conductance (a product of eggshell porosity) from the first definitively identified sauropod egg (Megaloolithus patagonicus) from the Auca Mahuevo locality in Argentina. We then compared the results with those from M. siruguei (an egg type long associated with sauropod dinosaurs) from the Pinyes locality in Spain. The 14-cm Auca Mahuevo egg has a thinner eggshell and 47 times fewer pores than the 22-cm M. siruguei specimen. The resulting water vapor conductance (GH2O) of the titanosaur and M. siruguei eggs is 341 and 3979 mg H2O day−1 Torr−1, respectively; these values are two and ten times greater than in avian eggs of comparable size, but lower than in eggs of most modern reptiles. Clutches from Auca Mahuevo typically contain 20–40 eggs; in contrast, M. siruguei clutches from the Pinyes site average nine eggs. The GH2O of M. siruguei exceeds that of the Argentine egg by an order of magnitude, supporting previous inferences of egg burial. The GH2O of the Argentine titan...