than 30 and the tooth row is oriented to the lateral sides as seen in other hadrosauroids, unlike the more advanced hadrosaurids. The upper toothless border of the dentary and a significant portion of the articular border for the predentary are missing, but given that both of these borders have minor lengths—about less than the 25% of the length of the dental battery—they indicate that the toothless area between the tooth row and the predentary was rather reduced—another trait present in hadrosauroids but lost in hadrosaurids. The predentary is represented by a complete element of specimen AMNH FARB 6369, which has a U-shaped form. Numerous and pointed denticles are preserved on the dorsal surface of the predentary, giving a serrated texture. Vertebral column The vertebral column is represented by four cervical, ten dorsal, seven sacral and thirty three caudal vertebrae of several specimens. The vertebrae are mostly similar to those of other hadrosauroids but some traits can be noted. The cervical vertebrae of specimens AMNH FARB 30671-30673 have centra that are opisthocoelous (concave on their posterior sides), heart-shaped in a posterior view and flattened on the inner side. The centra of the anterior dorsals in AMNH FARB 30674-3068 appear to be less opisthocoelous but they also have heart-shaped facets. The neural spines are very elongated and subrectangular in shape, they are slightly curved to the posterior side. In the middle and posterior dorsals of AMNH FARB 30681-30685 the neural spines are more straight and thicker. The preserved sacrum is composed by three elements, three fused vertebrae, four fused neural spines and four fused centra. Being relatively elongated, the centra in the three fused vertebrae are platycoelus (slightly concave at both ends) and have the lineal heart-shaped facets. When seen from the bottom surface, a ridge-like structure is located at the center as in Bactrosaurus, Claosaurus or Iguanodon. The neural canal—where the spinal cord passes through—is very large and expanded to the bottom. The four fused neural spines form a compact element, having very thickened and relatively elongated spines. The last sacral element is represented by four fused centra. These centra are widened to the lateral sides and while the posterior facet is lightly concave, the anterior one is more flattened. Lastly, the caudal vertebrae have very flattened centra with smally neural canals and neural spines that are projected towards the rear, although these traits become progressively marked towards the tail