[D] Laplatasaurus araukanicus [sG] [T]
Cretaceous Late Campanian Maastrichtian
Saurischia Sauropodomorpha Sauropoda Titanosauria
Castillo Formation, Bajo Barreal Formation, Laguna Palacios Formation, Rio Negro, Los Blanquitos Formation, Salta, Argentina; Asencio Formation, Palmitas, Urugay
Genus - Typespecies
From three major titanosaur quarries in Argentina, Huene, (1927) somewhat arbitrarily separated specimens repesenting most of the limb and girdle bones, which he took to bee a new slender-limbed some 50 percent larger than Saltasaurus, naming it L.araukanicus. He found no skull material, only two ore three presacrara and twenty caudals, ten of them articulated, as well as some juvenile material to go with the limbs. Bonaparte and Gasparini (1979) selected a tibia and fibula as the type of L.araukanicus. The importance of the specimens is that it represents the first report of body armor in a sauropod.
Caudal series, isolated limb elements.
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.
Laplatasaurus araukanicus Huene, 1929. An. Mus. La Plata, Paleont. III, 2nd Series, pp. 53-66, pls. 22-27.
M.L.P. 26-306 right tibia (C.S. 1128) and right fibula (C.S. 1127) illustrated by Huene (1929:pl. 27, figs. 1, 2). The initials C.S. corresponds to Cinco Saltos, identification with which was figured in the work of Huene.
Cinco Saltos, Río Negro Province (see Titanosaurus robustus)
Stratigraphic and chronological origin
Neuquén Group, Río Colorado or Allen. Pre-Maastrichtian Senonian.
Numerous remains from the postcranial skeleton, especially from Cinco Saltos and Rancho de Avila (Alamitos), Río Negro Province). Huene (op. cit.) assigned to this species material that Lydekker (1893) referred to Titanosaurus australis (op. cit., pls. 2, fig. 4; 4, figs. 1, 3).
Geographic, Stratigraphic, and Chronologic origin of the assigned material:
1. “Neuquén”. Neuquén Group. Upper Cretaceous, (material of Lydekker, 1893).
2. Cinco Saltos, Río Negro Province, Neuquén Group, Rio Colorado Formation or Allen Formation, Pre-Maastrichtian Senonian.
3. Vicinity of General Roca, Río Negro Province. Neuquén Group, probably Rio Colorado Formation Pre-Maastrichtian Senonian.
4. Rancho de Avila (Alamitos), Río Negro Province, Neuquén Group, probably Rio Colorado Formation. Pre-Maastrichtian Senonian..
5. Río Neuquén. Two km north of the railway bridge, on right bank. Neuquén Group, Rio Colorado Formation, possibly Bajo de la Carpa Member. Pre-Maastrichtian Senonian.
The knowledge of the species is based exclusively on material from the Neuquén Group (Neuquén and Río Negro Provinces), except that cited by Huene (1929:6) in which he refers to Laplatasaurus araukanicus from Sierra San Bernardino (Chubut Province) (“discovered by Riggs”).
This 400 VII Congresso Geologico Argentino material was not numbered or described and is probably deposited at the Field Museum of Chicago (USA). Because of the lack of a holotype, we have designated the lectotype for this species – a right tibia and fibula of the same individual, from Cinco Saltos, Río Negro .
Both pieces are characterized by being gracile and slender, traits that differentiate them clearly from those of Titanosaurus and partially from Antarctosaurus. Nevertheless, the fibula of Laplatasaurus is quite distinct from that of Antarctosaurus in the characters of the anterolateral process, as was emphasized by Huene (op. cit.: 62), in having two ridges formed by distinct osseous rugosities, while Antarctosaurus has only one ridge formed by two bony rugosities.
The scapula of Laplatasaurus (Huene op. cit.: 2, pl. 23) is clearly different from that of Titanosaurus, and to a lesser degree from Antarctosaurus. The humerus (Huene op. cit., pl. 23, fig. 4), with its distal extreme little expanded, is visibly distinct from that of Titanosaurus, Antarctosaurus, and Argyrosaurus.
On the basis of the noted differences we think that the validity of this genus and species is well documented. A difficult problem to resolve, as many discoveries do not pertain to associated and sufficiently complete material, consists in that we ignore whether the totality of material assigned to Laplatasaurus araukanicus corresponds to the same genus and species, or if it corresponds to forms not known at the present. For the most part, the genus and species are mostly endorsed by characters of the lectotype.
Source: Polyglot Paleontologist