Alwalkeria
| Alwalkeria | ||||||||||||
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Living reconstruction of Alwalkeria Maleriensis |
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| Temporal occurrence | ||||||||||||
| Upper Triassic ( Carnian ) | ||||||||||||
| 235 to 228 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Alwalkeria | ||||||||||||
| Chatterjee and Creisler , 1994 | ||||||||||||
| Art | ||||||||||||
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Alwalkeria is a genus of basal theropod dinosaur from the Upper Triassic of Asia. The type species Alwalkeria painteriensis is the onlyspecies described .
features
Alwalkeria was about the size of a turkey and probably an omnivore . The fossil remains of Alwalkeria - parts of the skull, remains of the vertebral bones and parts of the femur - were found in the Maleri formation in the valley of Godavari in the Indian state of Andhra Pradesh . These formations are dated to the time of the Upper Triassic. The fossils are parts of the upper and lower jaw , 28 damaged vertebrae from different areas of the spine , an almost complete femur and an ankle bone . The skull parts have a length of about four centimeters.
Alwalkeria has differently shaped teeth in the upper jaw, depending on their position in the jaw. The front teeth are slender and straight, while the rear teeth, like predatory theropods, have a broad base and are curved, but without a sawed edge. Due to the dentition, which can neither be completely limited to a vegetarian nor a purely predatory way of life, one assumes that Alwalkeria was an omnivore and probably ate insects, small vertebrates and plants.
Systematics
Although there are not very many remains, enough differences to the probably closely related eoraptor from South America could be recognized, especially in the shape and position of the teeth both species differ. With Eoraptor , he shares the gap between the teeth of the intermaxillary bone (premaxillary) and the maxillary maxillary on the upper jaw, which is the reason for the close relationship.
In contrast to Alwalkeria, Eoraptor has already been included in several cladistic works, but its position within the systematics of the dinosaurs has not yet been clarified. Langer regards it as a basal pelvic dinosaur , Paul Sereno classifies it as a basal theropod within the pelvic dinosaur, and Fraser et al. place him outside the dinosaur.
Naming
Sankar Chatterjee published the first scientific description in 1987 and chose Walkeria Maleriensis for the binomial , after the British paleontologist Alick Walker and the Maleri formation. The name had to be changed from Chatterjee and Creisler in 1994 because it was already taken.
literature
- Sankar Chatterjee : A new theropod dinosaur from India with remarks on the Gondwana-Laurasia connection in the Late Cretaceous. In: Garry D. McKenzie (Ed.): Gondwana Six. Stratigraphy, Sedimentology, and Paleontology (= Geophysical Monograph Series. Vol. 41). American Geophysical Union, Washington DC 1987, ISBN 0-87590-067-4 , pp. 183-189.
- Sankar Chatterjee, Benjamin S. Creisler: Alwalkeria (Theropoda) and Murturneria (Plesiosauria), new names for preoccupied Walkeria Chatterjee, 1987, and Turneria Chatterjee and Small, 1989. In: Journal of Vertebrate Paleontology. Vol. 14, No. 1, 1994, ISSN 0272-4634 , p. 142, doi : 10.1080 / 02724634.1994.10011546 .
- Nicholas C. Fraser, Kevin Padian , Gordon M. Walkden, ALM Davis: Basal dinosauriform remains from Britain and the diagnosis of the Dinosauria. In: Palaeontology. Vol. 45, No. 1, 2002, ISSN 0031-0239 , pp. 79-95, doi : 10.1111 / 1475-4983.00228 .
- Max C. Langer: Basal Saurischia. In: David B. Weishampel , Peter Dodson , Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 25-46, doi : 10.1525 / california / 9780520242098.003.0004 .
- David B. Norman : Problematic Theropods: Coelurosaurs. In: David B. Weishampel, Peter Dodson, Halszka Osmólska (eds.): The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 280-305.
- Paul C. Sereno : The evolution of dinosaurs. In: Science . Vol. 284, No. 5423, 1999, pp. 2137-2147, doi : 10.1126 / science.284.5423.2137 .
Individual evidence
- ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ 2010, ISBN 978-0-691-13720-9 , p. 68, online