Eoraptor
| Eoraptor | ||||||||||
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Skeletal reconstruction of Eoraptor lunensis in Brussels |
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| Temporal occurrence | ||||||||||
| Upper Triassic ( Carnian ) | ||||||||||
| 235 to 228 million years | ||||||||||
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| Scientific name | ||||||||||
| Eoraptor | ||||||||||
| Sereno , Forster , Rogers & Monetta , 1993 | ||||||||||
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Eoraptor ("hunter of the dawn") is a genus of very original dinosaurs from the early Upper Triassic ( Carnium ) of South America.
Its fossils were discovered in 1991 by an American-Argentinian research group in the rocks of the Ischigualasto Formation in Argentina. It is one of the oldest known dinosaurs, as its name alludes to, and is therefore important for understanding the early evolution of these living things. The only known species is Eoraptor lunensis . The species epithet refers to the location of the first skeleton in the "Valle de la Luna" (moon valley) in the Ischigualasto nature reserve .
features
Eoraptor grew no more than three feet and would have reached a human's knee. His skull was only four inches long. Its jaw was covered with teeth that were suitable for both the crushing of animal and vegetable food.
Scientists were able to obtain a lot of information about the early evolution of the dinosaurs from his fossils . In many ways it still resembled primitive two-legged reptiles like Lagosuchus , but the changed structure of the legs and the way they were connected to the pelvis clearly indicate that it was already a dinosaur.
Even if it is certain that Eoraptor was a dinosaur, its classification in the existing system is problematic, because Eoraptor is close to the origin of the dinosaurs when their diversification into the various large groups only began. Its physique was similar to that of later theropods and the claws and bones of carnivores. But in his jaw sat not only saw-edged teeth, which are characteristic of carnivorous theropods, but also those that resembled those of the prosauropods that ate plants. Eoraptor also lacked the intramandibular joint in the lower jaw ( mandible ), which in later theropods was used to hold larger prey better. Thanks to the find of Eoraptor, it is certain that the dinosaurs evolved from small, two-legged reptiles. Its location Argentina, where many other very old dinosaurs were found, is an indication that the origin of the dinosaurs could be in South America.
Systematics
The systematic classification within the dinosaurs is controversial. Although eoraptor has traditionally been mistaken for an original theropod (e.g., Sereno and colleagues, 1993; Currie, 1995), various other studies suggest that it must be classified outside of the theropod as an original Saurischia . Martinez and colleagues (2011), on the other hand, come to the conclusion that Eoraptor was an original representative of the sauropodomorpha (sauropod relatives).
literature
- Paul C. Sereno , Catherine A. Forster, Raymond R. Rogers, Alfredo M. Monetta: Primitive dinosaur skeleton from Argentina and the early evolution of Dinosauria. In: Nature , Vol. 361, No. 6407, 1993, pp. 64-66, doi : 10.1038 / 361064a0 .
- Sterling J. Nesbitt, Nathan D. Smith, Randall B. Irmis, Alan H. Turner, Alex Downs, Mark A. Norell : A complete skeleton of a Late Triassic saurischian and the early evolution of dinosaurs. In: Science . Vol. 326, No. 5959, 2009, pp. 1530-1533, doi : 10.1126 / science.1180350 .
Individual evidence
- ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ 2010, ISBN 978-0-691-13720-9 , pp. 6, 8, online .
- ↑ Eoraptor. In: The Paleobiology Database. Retrieved January 14, 2011 .
- ↑ Ricardo N. Martinez, Paul C. Sereno, Oscar A. Alcober, Carina E. Colombi, Paul R. Renne, Isabel P. Montañez, Brian S. Currie: A Basal Dinosaur from the Dawn of the Dinosaur Era in Southwestern Pangea. In: Science. Vol. 331, No. 6014, January 14, 2011, pp. 206-210, doi : 10.1126 / science.1198467 .
