Noasaurus

Noasaurus
Live artistic representation of Noasaurus
Temporal occurrence
Upper Cretaceous (early Maastrichtian )
72 to 69.9 million years
Locations
Argentina ( Lecho formation )
Systematics
Lizard dinosaur (Saurischia) Theropoda Ceratosauria Abelisauroidea Noasauridae Noasaurus
Scientific name
Noasaurus
Bonaparte & Powell , 1980
Art
Noasaurus leali

Noasaurus is a genus of theropod dinosaur from the group of Noasauridae . So far, only a single, fragmentary skeleton is known from the Upper Cretaceous (early Maastrichtian ) of Argentina . The only species is Noasaurus leali .

The name Noasaurus means something like "lizard from northwest Argentina" (NOA is an abbreviation for Spanish noroeste Argentinia - "northwestern Argentina"; Gr. Sauros - "lizard").

features

Noasaurus was a relatively small, two-legged carnivore with an estimated length of about 1.5 meters. The specimen found includes a strongly curved claw. While it was initially assumed that this claw sat on the second toe of the foot - analogous to the "sickle claws" of the Deinonychosauria - more recent studies come to the conclusion that it was actually a hand claw. The snout was blunt when viewed from the side, which is indicated by a high and short intermaxillary bone (premaxillary) - a typical feature of representatives of the Abelisauridae. There are only 11 tooth positions in the upper jaw found, some of them with preserved teeth that were slightly curved and toothed on both sides. The found parts of the cervical vertebrae indicate numerous cavities (pneumatization) and show a special morphology of the appendages on the upper side, which are otherwise only found in derived (advanced) representatives of the Abelisauridae such as Carnotaurus : The spinous processes were low, while the epipophyses behind the spinous processes were greatly elongated.

Research history, systematics and find

Noasaurus was described in 1980 by José Fernando Bonaparte and Jaime Eduardo Powell . These authors classified Noasaurus in a family of their own , the Noasauridae, in order to take account of the clear anatomical differences to other theropods known at the time. It was not until 2001 that a better known member of this family was described with Masiakasaurus . The relationships within the Noasauridae are unclear.

The only find (holotype, specimen number PVL 4061) comes from El Brete in the south of the Argentine province of Salta . It includes bones from different sections of the skeleton: cranial bones (upper jaw with teeth and a square leg ), vertebrae (fragments of one cervical and one dorsal vertebra and two cervical ribs), a metatarsal bone, as well as phalanges and hand claws have been passed down.

The find comes from the Lecho Formation , which is known for its rich vertebrate fauna. Finds of dinosaurs and birds from this formation include the titanosaur Saltasaurus and the early birds Enantiornis , Soroavisaurus , Yungavolucris and Lectavis .

literature

• Matthew T. Carrano, Scott D. Sampson: The Phylogeny of Ceratosauria (Dinosauria: Theropoda). In: Journal of Systematic Palaeontology. Vol. 6, No. 2, 2008, ISSN  1477-2019 , pp. 183-236, doi : 10.1017 / S1477201907002246 .
• Fernando E. Novas : The age of dinosaurs in South America. Indiana University Press, Bloomington IN 2009, ISBN 978-0-253-35289-7 .
• Federico L. Agnolin, Pablo Chiarelli: The position of the claws in Noasauridae (Dinosauria: Abelisauroidea) and its implications for abelisauroid manus evolution. In: Paleontological Journal. Vol. 84, No. 2, 2010, ISSN  0031-0220 , pp. 293-300, doi : 10.1007 / s12542-009-0044-2 .

Individual evidence

1. ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , p. 82, online .
2. ↑ ^{a b} Novas 2009 , pp. 268–270
3. ↑ Ben Creisler: Dinosauria Translation and Pronunciation Guide ( Memento of October 13, 2011 in the Internet Archive )
4. ↑ Agnolin and Chiarelli 2010
5. ↑ ^{a b c d} Carrano and Sampson , pp. 196-197
6. ↑ Novas 2009 , p. 149