Embryonic skin from Late Cretaceous Sauropods (Dinosauria) of Auca Mahuevo, Patagonia, Argentina

Abstract

We describe the integumentary anatomy of titanosaur sauropod embryos from the Auca Mahuevo nesting site. Natural (calcitic) casts of the skin show the non-imbricating, tuberculate scales (i.e., tubercles) typical of other non-avian dinosaurs. However, a variety of scale patterns previously unknown for the skin of these animals is reported. The observed integumentary patterns include ground tubercles, large and elongated tubercles, parallel rows of large tubercles, tubercles in rosette-like and flower-like arrangements, and in striate-like rows. Ground tubercles and rosette-like patterns resemble the few examples of skin known for adult sauropods. The former pattern also resembles the arrangement of osteoderms of the armored titanosaur Saltasaurus. Although the embryonic skin does not show definitive evidence of armor, the posthatching development of osteoderms cannot be ruled out. This material, the only available evidence of the embryonic skin of non-avian dinosaurs, contributes significantly to our knowledge of the integumentary morphology of these animals.