Neuquensaurus
| Neuquensaurus | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Neuquensaurus fossils |
||||||||||||
| Temporal occurrence | ||||||||||||
| Upper Cretaceous ( Santonium to Maastrichtian ) | ||||||||||||
| 86.3 to 66 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Neuquensaurus | ||||||||||||
| Powell , 1992 | ||||||||||||
| Art | ||||||||||||
|
Neuquensaurus ("Neuquén lizard") is a genus of sauropod dinosaur from the group of Titanosauria . Fossils come from the Upper Cretaceous ( Santonian to Maastrichtian ) Argentina . While most of the fossils from the Anacleto Formation have survived, fossils from the Lecho Formation have also been detected. Neuquensaurus is one of the best known representatives of the Titanosauria - so the postcranial skeleton is almost completely known. Skull bones have not yet been found. The only currently recognized species is Neuquensaurus australis .
features
With a length of about 8 meters, Neuquensaurus was one of the smallest known sauropods, so the thigh bone (femur) is only 0.75 m long. Its back was covered with skin bone plates (osteoderms), as in the related Saltasaurus . As with other representatives of the Saltasauridae, the tail was relatively short and could have served as a support in a possible straightening up on the hind legs.
This genus can be distinguished from other genera by various features of the axial skeleton and the appendicular skeleton . Important features can be found in the sacrum: Neuquensaurus had 7 sacral vertebrae, while other representatives of the Titanosauria had only 6 sacral vertebrae. In addition, the sacrum was narrowed from the third to the fifth sacral vertebrae. Special features of the Appendikulärskeletts show, inter alia, in the construction of the fibula (fibula), which is internally rotated and moved backward.
Two different morphs can be distinguished: a gracefully built and a robustly built morph. Von Huene (1929) assumed that the morphs represent two different species - while he attributed the finds of the graceful morph to the type species Neuquensaurus australis , he established the new species Neuquensaurus robustus , which should include the finds of the robust morph. Today's researchers reject this hypothesis and instead assume that the differences represent either individual variations or a sexual dimorphism .
Systematics
The systematics within the Titanosauria is highly controversial. In most studies, however , Neuquensaurus is the sister genus of Saltasaurus ; both genera are considered to be the most strongly derived (advanced) representatives of the Titanosauria. Saltasaurus and Neuquensaurus are often grouped together with Rocasaurus as Saltasaurinae . The Saltasaurinae, in turn, are classified together with a group called Opisthocoelicaudiinae within the Saltasauridae . The Saltasauridae represent the most strongly derived representatives of the Titanosauria.
John McIntosh (1990) comes to the conclusion that Saltasaurus and Neuquensaurus represent one and the same genus, since the differences between these genera are only marginal. However, later authors did not follow this suggestion.
Research history
The first finds were described by the British paleontologist Richard Lydekker in 1893 when he visited the La Plata Museum to examine the fossils in the museum's collection. Lydekker established a new species of the genus Titanosaurus on the basis of these findings - Titanosaurus australis . The genus Titanosaurus was described by Lydekker a few years earlier using remains from India. The species name of the new species, australis ( Latin for southern ), is intended to indicate the southern occurrence of the species. Lydekker (1893) notes that the majority of the Titanosaurus australis finds, including a series of vertebrae and bones of the fore and hind legs, come from a single site in the Neuquén province . The bones were found lying loosely on the surface of the site. Probably Lydekker did not visit this site himself; in any case, the source is not documented. Lydekker described two vertebrae from the same site as Titanosaurus nanus ; however, this species is no longer accepted today.
From 1921 to 1922, researchers at the La Plata Museum, led by paleontologist Santiago Roth, collected numerous remains from the Cinco Saltos site in the Río Negro province . The German palaeontologist Friedrich von Huene described these remains between 1923 and 1926; at the same time he subjected the finds already described by Lydekker to a new investigation. Von Huene divided the known fossils into two different types - Titanosaurus australis and Titanosaurus robustus . It was only with Powell's doctoral thesis (1986) that an extensive revision of the titanosaurs of South America appeared. Powell summarized the species Titanosaurus australis and Titanosaurus robustus within the new genus Neuquensaurus . More Neuquensaurus finds have since been described by Leonardo Salgado and colleagues (2005).
supporting documents
literature
- Michael D. D'Emic, Jeffrey A. Wilson: New remains attributable to the holotype of the sauropod dinosaur Neuquensaurus australis, with implications for saltasaurine systematics. In: Acta Palaeontologica Polonica. Vol. 56, No. 1, ISSN 0567-7920 , 2011, pp. 61-73, doi : 10.4202 / app.2009.0149 .
- Alejandro Otero: The appendicular skeleton of Neuquensaurus, a Late Cretaceous saltasaurine sauropod from Patagonia, Argentina. In: Acta Palaeontologica Polonica. Vol. 55, No. 3, 2010, pp. 399-426, doi : 10.4202 / app.2009.0099 .
- Leonardo Salgado , Sebastián Apesteguía, Susana E. Heredia: A new specimen of Neuquensaurus australis, a Late Cretaceous saltasaurine titanosaur from north Patagonia. In: Journal of Vertebrate Paleontology. Vol. 25, No. 3, 2005, ISSN 0272-4634 , pp. 623-634, doi : 10.1671 / 0272-4634 (2005) 025 [0623: ANSONA] 2.0.CO; 2 .
- Jeffrey A. Wilson: Overview of Sauropod Phylogeny and Evolution. Kristina Curry Rogers, Jeffrey A. Wilson (Eds.): The Sauropods. Evolution and Paleobiology. University of California Press, Berkeley CA et al. a 2005, ISBN 0-520-24623-3 , pp. 15-49, digitized version (PDF; 384.37 kB) .
- Jeffrey A. Wilson: An Overview of Titanosaur Evolution and Phylogeny. In: Fidel Torcida Fernández-Baldor, Pedro Huerta Hurtado (eds.): Actas de las III Jornadas Internacionales sobre Paleontología de Dinosaurios y Su Entorno. = Proceedings of the 3rd International Symposium about Paleontology of Dinosaurs and their Environment Paleontología de dinosaurios y su entorno. Salas de los Infantes (Burgos, España), 16 al 18 de septiembre de 2004. Colectivo arqueológico-paleontológico de Salas, Salas de los Infantes (Burgos, España) 2006, ISBN 84-8181-227-7 , pp. 169-190 .
Individual evidence
- ↑ a b c d d'Emic and Wilson 2011 , p. 64
- ↑ a b c d d'Emic and Wilson 2011 , pp. 61–63
- ↑ Otero 2010 , pp. 1–2
- ^ Wilson 2005 , p. 41
- ↑ Salgado et al. 2005 , p. 625
- ↑ Salgado et al. 2005 , p. 632
- ↑ Wilson 2006 , p. 182
- ↑ Salgado et al. 2005 , passim
