Preservation of an isolated tooth row in a dicraeosaurid sauropod dinosaur from Patagonia.

GARDERES, J.P.; GALLINA, P. A.; WHITLOCK, J.A.; TOLEDO, N.

Puerto Madryn

Jornada; Reunión Anual de Comunicaciones de la Asociación Paleontológica Argentina; 2018

CENPAT-CONICET

Isolated tooth rows (ITR) are a kind of fossil preservation where a set of articulated teeth are conserved altogether with little or no surrounding bonestructure associated. It has been proposed that these structures provide, along with a wrinkled pattern in the enamel surface of the tooth, an evidencefor the presence of a keratinous beak among Sauropoda. Hitherto, several ITR were recorded within Eusauropoda, such as in the basalShunosaurus, in the diplodocid Apatosaurus, in basal macronarian such as Europasaurus, Abydosaurus and Giraffatitan, and even in titanosaurianssuch as Phuwiangosaurus. Recently, the possible basal dicraeosaurid Lingwulong preserved an almost complete lower dentition as an isolated unit.The dicraeosaurid MMCh PV 75, from Bajada Colorada Formation, Neuquén, preserves an almost fully complete upper dentition as an ITR(lacking of only the fourth right maxillary tooth and the eighth left maxillary tooth), found in close association with other bones of the skull. Only the leftside shows a certain degree of tooth superposition with the first and second maxillary teeth over the fourth premaxillary tooth. It shows a ?U?-shapedperimeter as common in other flagellicaudatans. However it is more caudally constrained than the lower jaw, possibly due to plastic deformation.Although further studies will try to assess the presence of a wrinkled pattern in the enamel in order to test the presence of a keratinous beak, thepresence of an ITR in this taxon confirm this particular condition in dicraeosaurid sauropods as well as its wide distribution among Sauropoda.