ON DICRAEOSAURID (SAUROPODA) VERTEBRA FROM THE LA AMARGA FORMATION (BARREMIAN?APTIAN, LOWER CRETACEOUS), NEUQUÉN BASIN, PATAGONIA, ARGENTINA

WINDHOLZ, G.J.; BAIANO, M.A.; BELLARDINI, F.; MESO, J.G.; JUÁRES VALIERI, R.; PORFIRI, J.; FILIPPI, L.; GARRIDO, A.

Neuquén

Congreso; 2das Jornadas de Paleovertebrados de la Cuenca Neuquina; 2019

Field works carried out by Dr. Bonaparte and collaborators in the La Amarga Formation (Barremian?Aptian) in 2000, allowed the collecting of a vertebral element not previously communicated. This material has not been properly protected, so it is broken and kept in paleontological collection of Museo Provincial ?Olsacher? of Zapala city. The descriptions were based solely on a photograph. The parapophyses are located on the dorsal part of the centrum, like in the anterior dorsal vertebrae of Dicraeosaurus hansemanniJanensch and Amargasaurus cazauiSalgado and Bonaparte. The posterior articular surface of the centrum is strongly concave with an elliptical outline. The neural arch bears two deep and wide centropostzygapophyseal fossae with a triangular outline. These fossae are framed laterally by stout centropostzygapophyseal laminae, project dorsoventrally like a massive columnar bone. The transverse processes are inclined dorsally more than 30° from the horizontal axis, as in the dorsal vertebrae of D. hansemanni, A. cazaui, Brachytrachelopan mesaiRauhut, Remes, Fechner, Cladera and Puerta and Pilmatueia faundeziCoria, Windholz, Ortega and Currie. The element bears an elongate bifid neural spine, character that share with the most of presacral vertebrae of the dicraeosaurids. This structure is straight, dorsoanteriorly oriented and its degree of development reminds to the presacral vertebrae of A. cazaui. This element is similar to the anterior dorsal vertebrae of A. cazaui, although it could be comparable with Amargatitanis macniApesteguía, come from the same locality and lithostratigraphic unit, whose presacral vertebrae are unknown.