The dentition of dicraeosaurid sauropod dinsaursResúmenes

JUAN PABLO GARDERES; PABLO ARIEL GALLINA

Santa Clara del Mar

Jornada; Jornadas Argentinas de Paleontología de Vertebrados XXXI; 2017

Tooth shape and size of dicraeosaurid sauropod are known from isolated functional elements assigned to Dicraeosaurus hansemanni Janensch 1914 and Amargasaurus cazaui Salgado and Bonaparte 1991, and/or from a few replacement teeth recovered in the tooth bearing bones from Dicraeosaurus and Suuwassea emilieae Harris and Dodson 2004. The characteristic shape of these teeth is peg-like, narrow-crowned lingual curved structures. While enamel pattern was not preserved in Dicraeosaurus, in Suuwassea shows a convolute design. The nearly complete tooth-bearing bones of a new dicraeosaurid sauropod (MMCh-PV 75) from the Lower Cretaceous of Bajada Colorada Formation (Northern Patagonia, Argentina) critically expands the knowledge of tooth shape and size, in both functional and replacement elements. Besides, the total number of teeth can be asserted. The count in the upper row includes 4 teeth in the premaxilla and 8 in the maxilla. Along the tooth row, the size of these elements decreases backwards. Premaxillary teeth are straight to slightly convex labially, from the symphysis to the maxilla. Conversely, maxillar teeth are lingually concave to straight anteroposteriorly. Besides, maxillary teeth 1-5 are slightly curved backward distally. In the lower jaw, the dentary exhibits 12 alveoli with fully growth teeth, showing the same decreasing pattern in size than the upper row. However, these teeth show a nearly straight edge along the row, with minimal signal of curvature. The found of a complete dentition of a dicraeosaurid allows the recognition of novel patterns in tooth size reduction and curvature variation along the tooth row in diplodocoids sauropods.