Antarctosaurus (; meaning "southern lizard") is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Period of what is now South America. The type species, Antarctosaurus wichmannianus, and a second species, Antarctosaurus giganteus, were described by prolific German paleontologist Friedrich von Huene in 1929. Three additional species of Antarctosaurus have been named since then but later studies have considered them dubious or unlikely to pertain to the genus. The type species, A. wichmannianus, is controversial because there is uncertainty as to whether all the described remains belong to the same individual or even genus. The second species, A. giganteus, is considered dubious, but the fragmentary remains represent one of the largest dinosaurs known. Discovery and species Remains of this dinosaur were first mentioned in print in 1916, although they were not fully described and named until a 1929 monograph written by paleontologist Friedrich von Huene. Antarctosaurus does not refer to the continent of Antarctica since it was first found in Argentina, although it does have the same derivation, from the Greek words αντι-, anti- meaning 'opposite of', αρκτός, arktos meaning 'north' and , sauros meaning 'lizard'. The generic name refers to the animal's reptilian nature and its geographical location on a southern continent. Antarctosaurus wichmannianus is the type species of the genus, named in 1929 after the discoverer of its remains in 1912, geologist Ricardo Wichmann. Von Huene used the name A. wichmannianus to describe a large assemblage of bones, which are considered to come from the Anacleto Formation in Río Negro Province of Argentina, which is probably early Campanian in age. Two additional limb bones, found in the Chubut Province in 1924, were also referred to A. wichmannianus by von Huene in 1929. Later studies, however, have doubted their referral to the species. Von Huene also named a fragmentary second species of Antarctosaurus in the same 1929 monograph, which he tentatively called cf. Antarctosaurus giganteus because of its enormous size. These fossils were recovered in Neuquén Province of Argentina, from the Plottier Formation, which dates to the Coniacian-Santonian stages of the Late Cretaceous Period. The Plottier, like the younger Anacleto, is a member of the Neuquén Group. Very few remains are known of this species and it is regarded as a nomen dubium by some. Other researchers regard A. giganteus as a likely valid species but probably belonging to a new genus. In 1969, Leigh Van Valen considered