[D] Titanosaurus australis
Cretaceous Late Maastrichtian
Saurischia Sauropodomorpha Sauropoda Titanosauria
Rio Colorado Formation, or Allen Fm., Provincia de Neuquen; Provincia de Rio Negro Argentina
Saltasaurus [Asencio Formation, Palmitas, Urugay]
Neuquensaurus australis [Rio Colorado Formation, or Allen Fm., Provincia de Neuquen; Provincia de Rio Negro Argentina]
< 8 meter
Neuquensaurus australis Powell, 1986) > Saltasaurus australis (Lydekker, 1893) > Titanosaurus australis (Lydekker, 1893)
Saltasaurus (Bonaparte & Powell, 1980) = Microcoelus (Lydekker, 1893) Loricosaurus (Huene, 1929)
Saltasaurus > Saltasaurus loricatus (Bonaparte & Powell, 1980) > Saltasaurus robustus (Huene, 1929) = Titanosaurus robustus (Huene, 1929)
Saltasaurus > Saltasaurus australis (Lydekker, 1893) = Titanosaurus australis (Lydekker, 1893) >> Microcoelus patagonicus (Lydekker, 1893) Loricosaurus scutatus (Huene, 1929) Titanosaurus nanus (Lydekker, 1893)
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.
Titanosaurus australis Lydekker, 1893. An. Mus. La Plata, Paleont. Argentina. II, pp. 3-8, pls. 1-3; figs. 4, 7.
Museo La Plata M.L.P. 77-V-28-1. Six caudal vertebrae (Lydekker, 1893:4, pl. 1).
Huene specified that the original material of Lydekker of this species comes from the vicinity of Neuquén “…in the elevated right cliff of the Río Neuquén, some kilometers (2-4) from the railway bridge and in the confluence before Neuquén”. If this provenance is correct, the chronostratigraphic assignments are as follows:
Stratigraphic and chronological origin:
Neuquén Group, Río Colorado Formation, possibly Bajo de la Carpa Member. Pre-Maastrichtian Senonian.
Abundant material corresponding to various individuals, represented in their totality by postcranial skeletons.
Geographic, Stratigraphic, and Chronologic origin of the assigned material:
1. Neuquén. Neuquén Group. Material described by Lydekker 1893). Note that Huene (op. cit. 24-25) cited the origin in quotation marks: “Neuquén”.
2. Cinco Saltos, Río Negro Province. Neuquén Group, Río Colorado or Allen Formation. Pre-Maastrichtian Senonian. The majority of material assigned to this species comes from this locality (see Huene, op. cit., 24-25).
3. Facing General Roca, Río Negro Province. Neuquén Group, Río Colorado Formation. Pre-Maastrichtian Senonian.
4. Alarcón, left bank of the Río Limay, Neuquén Province. Neuquén Group. Pre-Maastrichtian Senonian. Huene (op. cit.) mentioned a vertebra but did not illustrate it.
In the first place it is evident that the material referred to Titanosaurus (Titanosaurus australis and Titanosaurus robustus) from Patagonia pertains to a genus distinct from Laplatasaurus, Argyrosaurus, and Antarctosaurus. Among other details, because of a very marked difference in the morphology of the humerus, an element preserved in all taxa cited, and in the scapula, also known in all species except Argyrosaurus.
Titanosaurus australis was named by Lydekker (1893) on the basis of poor material from Neuquén. Later Huene (1929) confirmed the probable validity of this species from an abundant collection coming from Cinco Saltos, Río Negro Province. Huene indicated in several paragraphs of his monograph (op. cit.: 23, 46, 47) that the material pertaining to different exemplars was mixed. Notwithstanding, as he emphasized, this does not induce very significant errors as those in selecting material of this species for morphological characters of count and proportions. Although these are not infallible, when managed by a paleontologist of the prestige of Huene they deserve a high grade of confidence.
In synthesis, Titanosaurus australis is a species well known by its postcranial skeleton, which requires comparison with new discoveries to confirm some morphological aspects, such as the proportions of the distinct segments of the limbs and cranial characters. Titanosaurus australis is known only from the upper sector of the Neuquén Group, having been documented in some of the fossilliferous localities of this geological group. Its absence in other localities of the same group as well as in the Chubut Group may have arisen from defects of the record, or ecological requirements of the species.
Source: Polyglot Paleontologist