[D] Antarctosaurus wichmannianus [Su] [T]
Cretaceous Late, Campanian Maastrichtian
Saurischia Sauropodomorpha Sauropoda Titanosauria
Castillo Formation, Bajo Barreal Formation, Laguna Palacios Formation, Rio Colorado Formation or Allen Fm. Provincia de Neuquen, Provincia de Rio Negro, Rio Neuquen Formation, Provincia de Neuquen, Bajo Barreal Formation, Chubut, Argentina; Asencio Formation, Palmitas, Urugay, Vinitas Formation, Coquimbo, Chile
Typespecies - Skull
Antarctosaurus > Antarctosaurus wichmannianus (Huene, 1929) Antarctosaurus giganteus (Huene, 1929) > Antarctosaurus brasiliensis (Arid& Vizotto, 1972)
Partial skeleton, including braincase, mandible and most of the limbs.
Part of: Bonaparte, J. F. and Z. Gasparini. 1979. Los saurópodos de los grupos Neuquén y Chubut, y sus relaciones cronologicas. Actas del VII Congreso Geológico Argentino, Neuquén 2:393-406. [The sauropods of the Neuquén and Chubut groups and their chronological relations]
Translated by Jeffrey A. Wilson, Museum of Paleontology, University of Michigan, January 2003.
Antarctosaurus wichmannianus Huene, 1929. An. Mus. La Plata, III 2nd series, pp. 66-75, pls. 28-35.
Holotype: Museo Argentino de Ciencias Naturales M.A.C.N. 6.804. An incomplet skull and mandible, rib fragment, an incomplete right humerus, a distal fragment of the ulna, distal fragments of two radii, two incomplete metacarpals, an ungual phalanx, a right ischium, a distal fragment of a pubis, a left tibia, a fragment of a right fibula, a left calcaneum, various pedal phalanges, a posterior cervical vertebra, a left scapula and a fragment of a right ulna, a proximal fragment of a radius, six incomplete metacarpals, a phalanx, a posterior fragment of an ilium, an incomplete left ischium, a left femur, a left fibula, four or five left metatarsals. All elements pertain to the same individual.
Geographic origin: In front of General Roca, on the southern coast of the Río Negro, Río Negro Province.
Stratigraphic and chronological origin: Neuquén Group, Rio Colorado Formation, probably Bajo de la Carpa Member. Pre-Maastrichtian Senonian.
Referred material: to Antarctosaurus cf. A. wichmannianus: A right femur and a left tibia (Huene, 1929:74, figs. 33, 34). Collection of the Field Museum of Chicago, United States of America.
Geographic, Stratigraphic, and Chronologic origin: Sierra San BernarJ. F. Bonaparte& Z. B. De Gasparini, The sauropods of the, etc. 401 do, 45 km west of Colonia Sarmiento. Chubut Group, Castillo or Bajo Barreal Formation. Pre-Maastrichtian Senonian
Commentary: The abundant material of the holotype pertains, according to available evidence (Wichmann, 1916; Huene, 1929) to one single individual. Nevertheless, among the material collected from this place are some bony elements that Huene did not attribute to A. wichmannianus because of their proportionally small size.
From the Chubut Group, outcropping in the are of the Sierra San Bernardo, comes a femur and tibia that Huene referred with doubts to this species, although he noted that “the tibia has the same conformation and the same proportions as that described from Roca (1929:75), obviously referring to the holotype material.
According to the available evidence, the genus and species are valid by our judgement. The fundamental osteological characters clearly differentiate it from Titanosaurus. These are of a significance that probably correspond to distinctions at the subfamiliar or familiar level. The strong differences in the scapula, humerus, fibula, etc., support this hypothesis. On the other hand, the similarities with Laplatasaurus are greater, although its distinction at the generic level are evidenced by differences in the acromial region and the posterior margin of the scapula, in the distal half of the humerus, the morphology of the metacarpals, and particularly in the distinct comformation of the tuberosities of the anterolateral process of the fibula.
The study of the braincase, both mandibles, and their dentition demonstrate affinities with Diplodocus (Upper Jurassic of North America). These similarities could be considered the product of adaptive convergence in distinct lineages and epochs.
Source: Polyglot Paleontologist