The Late Cretaceous nesting site of Auca Mahuevo (Patagonia, Argentina): eggs, nests, and embryos of titanosaurian sauropods.

Luis M. Chiappe, Rodolpho. . Coria, Frankie D. Jackson and Lowell Dingus

The late Cretaceous Auca Mahuevo nesting site (Neuquén Province, Argentina) has produced a large number of sauropod eggs, many of them containing the remains of embryos. Research at this site has generated important information about the development of the embryos, the morphology and eggshell microstructure of the eggs, and the reproductive behavior of sauropod dinosaurs. Cranial features present in the embryos have allowed their identification as those of titanosaurian sauropods. Differences in the texture of the sediments that contain some of the egg-clutches have illuminated their nest architecture. Microstructural studies of eggshells have expanded our knowledge of their variability and the incidence of pathologies within a reproductive titanosaurian population. Maps showing the spatial distribution of eggs and clutches. the stratigraphic distribution of the egg-beds, and the sedimentological context in which they are contained, have provided the basis for several inferences about the nesting behavior of these dinosaurs.