Ligabuesaurus leanzai gen. et sp. nov. (Dinosauria, Sauropoda), a new titanosaur from the Lohan Cura Formation (Aptian, Lower Cretaceous) of Neuquén, Patagonia, Argentina

Ligabuesaurus leanzai gen. et sp. nov. is a new titanosaur (Saurischia, Sauropoda) from the Lower Cretaceous of Neuquén Basin, north Patagonia, Argentina. The fossil remains were found in the upper section of the Lohan Cura Formation, which is regarded as Late Aptian–Albian in age. Remains include an incomplete maxilla with ten teeth, six cervical and dorsal vertebrae, and several associated girdle and limb bones. Ligabuesaurus is characterized by: (1) laminar and anteroposteriorly compressed neural spines on posterior cervical and anterior dorsal vertebrae that are rhomboid in shape and wider than vertebral centra; (2) spinoprezygapophyseal laminae in the posterior cervical vertebrae forked to form two pairs: the medial laminae contact one another toward the tip of the neural spine, and the lateral pair form the lateral border of the neural spine; (3) dorsoventrally reduced neural arch pedicels in posterior cervical and anterior dorsal vertebrae; and (4) rudimentary prespinal lamina on posterior cervical and anterior dorsal vertebrae. A preliminary phylogenetic analysis suggests that Ligabuesaurus is a basal titanosaur. The development of relatively long forelimbs, with a humerus/femur ratio of 0.9, indicates that this condition is not an exclusive adaptation of the Brachiosauridae.