Pitekunsaurus macayai gen. et sp. nov., nuevo titanosaurio (Saurischia, Sauropoda) del Cretácico Superior de la Cuenca Neuquina, Argentina

a new titanosaur is described, pitekunsaurus macayai gen. et sp. nov., from mudstone levels asigned to anacleto formation (lower - middle campanian), corresponding to the uppermost beds of the neuquén group (upper cretaceous of neuquén basin). the specimen is represented by braincase, left frontal, one tooth, four cervical vertebrae, three dorsal vertebrae, four caudal vertebrae, right ulna and scapula, proximal extreme of left femur, rib fragments and uncertain remains. pitekunsaurus is characterized by the following autapomorphies: (1) basipterygoid processes broadly separated and parallelly projected, (2) anterior cervical vertebrae with small depressions or longitudinal grooves in the spinal sector of spinopostzygapophyseal lamina, (3) centropostzygapophyseal lamina forked proximally in anterior dorsal vertebrae, and (4) posterior centrodiapophyseal lamina with accessory lamina in anterior dorsal vertebrae. the existence of two types of articulations in the posterior caudal vertebrae, one amphicoelous and another biconvex, indicates a close relationship with rinconsaurus caudamirus calvo y gonzález riga, suggesting that the caudal morphology of titanosaurs is much more complex and more varied than previously supposed.