page_title: Antarctosaurus
section_title: "Antarctosaurus" giganteus
hierarchical_section_title: Antarctosaurus / Description / "Antarctosaurus" giganteus
caption_attribution_description: Español: Fémures del dinosaurio Antarctosaurus giganteus. Formación Río Colorado, Río Negro, Argentina, Cretácico tardío (83-65 Ma)
context_page_description: Antarctosaurus 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.
context_section_description: The type specimen of A. giganteus, MLP 26-316, includes a left and right femur, a partial left and right pubis, the distal end of a damaged tibia, numerous rib and distal caudal vertebrae fragments, and six large and unidentifiable bones. The two gigantic femora measure 2.35 meters (7.7 ft) in length, which are among the largest of any known sauropod. Even though the femurs are large, they are also somewhat gracile in construction. 
  A reconstruction of A. giganteus, published in 1956 by Carlos Rusconi, was given a length around 30 meters (98 ft). In 1969, van Valen considered it as similar in size to Giraffatitan brancai (then called Brachiosaurus brancai). Based on an earlier mass estimate of G. brancai by Edwin Harris Colbert in 1962, van Valen gave A. giganteus an estimated mass of about 80 metric tons (88 short tons). In 1994, Gregory S. Paul estimated the weight of both A. giganteus and Argentinosaurus at between 80 and 100 metric tons (88 and 110 short tons) and lengths of 30 to 35 meters (98 to 115 ft) long. Extrapolating from the femur's parameters, a 2004 study by Gerardo Mazzetta and colleagues estimated the mass of A. giganteus at approximately 69 metric tons (76 short tons); slightly smaller than Argentinosaurus which in the same study was estimated at nearly 73 metric tons (80 short tons). This would make A. giganteus among the heaviest known land animals. In 2006, Kenneth Carpenter used the short-necked Saltasaurus as a guide and estimated a shorter length of 23 meters (75 ft) long.   In 2012 Thomas holtz gave a length of 33 meters and an estimated weight of 58-65 metric tons (64-72 short tons). 
  In 2016, using equations that estimate body mass based on the circumference of the humerus and femur of quadrupedal animals, it was estimated to be 39.5 metric tons (43.5 short tons) in weight. In 2019, Gregory S. Paul estimated the mass of A. giganteus in the 45 to 55 metric tons (50 to 61 short tons) range, based on newer titanosaur reconstructions. In 2020 Molina-Pérez and Larramendi estimated its length at 30.5 meters (100 ft) and its weight similar to Paul's estimation at 45 metric tons (50 short tons). Due to the incompleteness of the remains, any size estimates are subject to a large amount of error.
caption: Antarctosaurus giganteus femora in La Plata Museum
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