Describing
Antarctosaurus is problematic because the
type species consists of elements that are of questionable association and none of the species described are known from complete remains, which has caused a confused
taxonomy of the genus. a group of large-bodied,
quadrupedal
herbivores, usually possessing a long neck and tail, with a small head.
Antarctosaurus wichmannianus The assemblage of fossil remains that became known as
A. wichmannianus were given the specimen number MACN 6904. The total length of
A. wichmannianus has been estimated at around . An additional femur and
tibia were also referred by von Huene to
A. wichmannianus; the femur, FMNH P13019, is over tall. In one study the dimensions of this femur were used in a
regression analysis to estimate the mass of
A. wichmannianus at about . The referral of the additional femur and tibia has been questioned by later researchers. In 2003
Jaime Eduardo Powell tentatively referred them to
cf. Argyrosaurus and in 2012 Philip Mannion and Alejandro Otero considered it an indeterminate titanosaur. The incomplete
mandible attributed to
A. wichmannianus is squared-off at the front with each dentary bone being
L shaped. The teeth were restricted to the front of the lower jaw and were small and slender. However, the jaw of
Bonitasaura, described in 2004
, is similar in overall shape and is clearly associated with titanosaur skeletal remains, indicating that the lower jaw may belong to
A. wichmannianus after all. In 2013 and 2018 respectively,
Brasilotitan and
Baalsaurus were described which also possessed squared-off jaws.
Brazilotitan and
Baalsaurus were described as a titanosaurs, closely related
to A. wichmannianus. In 2005,
Jeffrey Wilson considered the braincase as being referable to
Nemegtosauridae but noted that other skull remains require further study. Powell compared the width of the cranium to the length of the limb bones of both
A. wichmannianus and
Saltasaurus; this led him to conclude that the skull was proportionally small in
A. wichmannianus, this might imply that the skull and limb elements could belong to different individuals or a different
taxa. He noted, however, that the comparison was potentially misleading because the overall anatomy of
Saltasaurus is shorter and stouter which might facilitate a bigger skull. Powell thought it was probable that von Huene correctly assigned the material to
A. wichmannianus, arguing that von Huene would have been able to communicate with the discoverers and would have had access to photographs of the discovery site. Extrapolating from the femur's parameters, a 2004 study by Gerardo Mazzetta and colleagues estimated the mass of
A. giganteus at approximately ; slightly smaller than
Argentinosaurus which in the same study was estimated at nearly . This would make
A. giganteus among the heaviest known land animals. In 2019,
Gregory S. Paul estimated the mass of
A. giganteus in the range, based on newer titanosaur reconstructions. In 2020 Molina-Pérez and Larramendi estimated its length at and its weight similar to Paul's estimation at . Due to the incompleteness of the remains, any size estimates are subject to a large amount of error. Paleontologist
Teresa Maryańska noted that, whilst
A. jaxarticus was named, it was not properly described or diagnosed. The femur possibly belongs to the titanosaur clade
Lithostrotia. The type specimen of
"Antarctosaurus" brasiliensis is only known from three fragmentary bones that are titanosaurian in nature; a partial left femur GP-RD-2, a partial right
humerus GP-RD-3, and an incomplete
dorsal vertebra (backbone) GP-RD-4. The femur is preserved and was estimated at if it were completed. The humerus is preserved and estimated at completed. The dorsal vertebra
centrum is long. ==Classification==