Arackar licanantay gen. et sp. nov. a new lithostrotian (Dinosauria, Sauropoda) from the Upper Cretaceous of the Atacama Region, northern Chile

ABSTRACT A new lithostrotian sauropod, Arackar licanantay gen. et sp. nov. is described based on a partial skeleton from the Upper Cretaceous (Campanian–Maastrichtian) beds of the Hornitos Formation, Atacama Region, northern Chile. The holotype consists of axial (cervical and dorsal vertebrae) and appendicular (humerus, femur and ischium) elements of a sub-adult specimen (ca. 6.3 m long). Autapomorphies characterizing this new titanosaur include: wide and tall centroprezygapophyseal fossa + parapophyseal centroprezygapophyseal fossa extended on the entire anterior faces of the pedicles of the neural arch, but not above the neural canal; postzygapophyseal processes narrower than the neural spine, with reduced spinopostzygapophyseal laminae, shorter than the postzygapophyseal facet length. A phylogenetic analysis based on a data matrix of 87 taxa and 405 characters recovered Arackar as a derived lithostrotian titanosaur, placing in a clade that includes Rapetosaurus + (Arackar + Isisaurus). This is the third titanosaur dinosaur named from the Chile and western side of the Andes in South America.