PRESERVATION OF AN ISOLATED TOOTH ROW IN A DICRAEOSAURID SAUROPOD DINOSAUR FROM PATAGONIA

JUAN PABLO GARDERES; PABLO ARIEL GALLINA; JOHN ANDREW WHITLOCK; NÉSTOR TOLEDO

Congreso; Reunión de Comunicaciones de la Asociación Paleontológica Argentina; 2018

.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 intitanosaurians such as Phuwiangosaurus. Recently, the possible basal dicraeosaurid Lingwulong preserved an almost complete lower dentitionas an isolated unit. The dicraeosaurid MMCh PV 75, from Bajada Colorada Formation, Neuquén, preserves an almost fully complete upperdentition as an ITR (lacking of only the fourth right maxillary tooth and the eighth left maxillary tooth), found in close association with other bones ofthe skull. Only the left side shows a certain degree of tooth superposition with the first and second maxillary teeth over the fourth premaxillary tooth.It shows a ?U?-shaped perimeter as common in other flagellicaudatans. However it is more caudally constrained than the lower jaw, possibly dueto plastic deformation. Although further studies will try to assess the presence of a wrinkled pattern in the enamel in order to test the presence ofa keratinous beak, the presence of an ITR in this taxon confirm this particular condition in dicraeosaurid sauropods as well as its wide distributionamong Sauropoda.