New Dicraeosauridae (Sauropoda, Diplodocoidea) remains from the La Amarga Formation (Barremian–Aptian, Lower Cretaceous), Neuquén Basin, Patagonia, Argentina

Abstract

Dicraeosauridae is a family of small body-sized sauropod dinosaurs that diversified from the Middle Jurassic to the Lower Cretaceous, whose distinctive feature is a long dorsally projected, bifid neural spines in most of the presacral vertebrae. The dicraeosaurid fossil record is limited to few taxa, therefore each new finding, however fragmentary, allows to improve the knowledge about this group. Here, we report new dicraeosaurid remains, consisting of two associated anterior dorsal vertebrae (MOZ-Pv 6126-1; MOZ-Pv 6126-2) collected from the La Amarga Formation (Barremian–Aptian, Lower Cretaceous). MOZ-Pv 6126-1 is represented by an almost complete anterior dorsal vertebra, while MOZ-Pv 6126-2 is an anterior dorsal vertebral centrum with a portion of the neural arch. The morphological features of these axial elements, as well as the absence of lateral fossae, the orientation of the transverse processes and an elongated bifid neural spine, allow us to refer them to the dicraeosaurid sauropods. However, due to the lack of more diagnostic features, we prefer to consider MOZ-Pv 6126-1 and MOZ-Pv 6126-2 as Dicraeosauridae indet. The new materials increase the fossil record of dicraeosaurid sauropods from La Amarga Formation and enrich the poor worldwide fossil record of the Dicraeosauridae.