[D] Argyrosaurus superbus [sG] [T]
Cretaceous Late Campanian Maastrichtian
Saurischia Sauropodomorpha Sauropoda Titanosauria
Castillo Formation, Bajo Barreal Formation, Laguna Palacios Formation, Chubut; Bajo Barreal Formation, unnamed unit, Santa Cruz, Argentina; Asencio Formation, Urugay
Genus - Typespecies
Argyrosaurus superbus was founded on a gigantic forelimb and foot from the Late Cretaceous of Argentina, and largely for that reason, it has been considered a titanosaurid.
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.
Argyrosaurus superbus Lydekker, 1893. An. Mus. La Plata. Paleontología. Argentina, II, pp. 9-12, pl. 5; figs. 1-1A.
Holotype: Museo La Plata M.L.P. 77-V-29-1. Articulated left forelimb composed of a humerus, radius, ulna, one or two carpal bones, and five metacarpals.
Geographic origin: Left bank of the Río Chico, near the Pampa Pelada, to the northeast of Lake Colhué-Huapi, Chubut.
Stratigraphic and chronological origin: Chubut Group, probably Bajo Barreal Formation. Pre-Maastrichtian Senonian.
Assigned material: The assigned material comes from 8 localities, some of which do not correspond to the provinces of Chubut and Neuquén mentioned thus far. For this reason, they are listed with geographic, stratigraphic, and chronologic provenance.
1. An anterior caudal vertebra (Huene, 1929:79). West bank of Lake Colhué-Huapi, Chubut Province. Chubut Group, Castillo Formation or Bajo Barreal Formation. Pre- Maastrichtian Senonian.
2. Two caudal vertebrae “…of the region of Neuquén” (Huene op. cit.:7). Geographic and stratigraphic provenance unknown.
3. An incomplete femur (Lydekker, 1893, pl. 5, 2; Huene, 1929:80, pl. 38, 1). To the south of the bend of the Río Sengerr, Chubut Province, probably Bajo Barreal Formation. Pre-Maastrichtian Senonian.
4. An incomplete right femur (Huene, op. cit.:80, pl. 38, 2). Near the railroad bridge over the Río Neuquén, Neuquén Province. Neuquén Group, Río Colorado Formation, perhaps Bajo de la Carpa Member. Pre-Maastrichtian Senonian.
5. A complete right femur (Huene, op. cit.:80-81, pl. 38, 3). Sierra San Bernardino, 45 km west of Colonia Sarmiento, Chubut Province. Chubut Group. Bajo Barreal Formation. Pre-Maastrichtian Senonian.
6. A humerus of a juvenile individual, referred with doubts to Argyrosaurus (Huene, op. cit.:81, pl. 37, 6). Probably from Neuquén. Uncertain geographic and stratigraphic provenance.
7. A left humerus, referred with doubts to Argyrosaurus superbus Huene, op. cit.:81, pl. 37, 4). Left margin of the Río Uruguay, near Colón, Entre Ríos Province. ?Asencio Formation. Upper Cretaceous.
8. Caudal vertebrae (Huene, op. cit.:79). To the east of the Río Leona, between lakes Viedma and Argentino, Santa Cruz Province, Upper Cretaceous (Dibenedetto, pers. comm.).
Commentary: The validity of this species is based principally on the characters of the robustness of the humerus and to a lesser extent on the bones of the antebrachium. This characteristic, which involves its own morphological traits, differentiates A. superbus from the rest of the sauropods from the Cretaceous of Patagonia. The isolated bones of the hindlimb assigned to this species coincide in being heavy and robust. Nevertheless, for the moment it cannot be affirmed whether they pertain to A. superbus, but neither can it be denied that this robustness is not observed in the species of Titanosaurus, Laplatasaurus, or Antarctosaurus.
The holotype comes from sediments of the Chubut Group, relatively near Lake Colhué-Huapi. Of the material assigned, the most significant comes from the area of Sierra San Bernardo and of the Neuquén Group. Although it is certain that the most interesting material registered in the Neuquén Group, an incomplete femur, is not final evidence of the presence of A. superbus, the morphological characters preserved are undoubtedly comparable to the femora of Sierra San Bernardo illustrated by Huene (op. cit., pl. 38, 1, 3). Or it could be that we have before us a taxon common to the Chubut and Neuquén Groups represented by these femora that, as in the interpretation of Lydekker (1893, pl. 5, 2) and Huene (op. cit., pl. 38, 1-3), could very well pertain to Argyrosaurus superbus. We think that this question requires verification, but we admit that the available evidence is very significant in showing a common taxon in both geological groups.
Source: Polyglot Paleontologist
Mannion, P. D.; Otero, A. (2012). A reappraisal of the Late Cretaceous Argentinean sauropod dinosaur Argyrosaurus superbus, with a description of a new titanosaur genus. Journal of Vertebrate Paleontology 32 (3): 614–638. doi:10.1080/02724634.2012.660898
Argyrosaurus superbus is one of the earliest-named Argentinean dinosaurs. The holotype comprises a complete forelimb, probably from the upper member of the Bajo Barreal Formation (Late Cretaceous), Chubut Province. Numerous remains have been referred to Argyrosaurus from Argentina and Uruguay; however, the type specimen has not been adequately diagnosed and referrals have predominantly been based upon their large size. Here we redescribe Argyrosaurus, demonstrating it to be a valid titanosaur genus based on five autapomorphies, as well as an unique character combination. The exact placement of Argyrosaurus within Titanosauria is uncertain, although the probable presence of carpal bones, otherwise unknown in titanosaurs, may indicate a basal position.