Adasaurus
| Adasaurus | ||||||||||||
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Live reconstruction |
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| Temporal occurrence | ||||||||||||
| Upper Cretaceous (early Maastrichtian ) | ||||||||||||
| 72 to 69.9 million years | ||||||||||||
| Locations | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Adasaurus | ||||||||||||
| Barsbold , 1983 | ||||||||||||
| Art | ||||||||||||
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Adasaurus is a genus of carnivorous dinosaurs from the Dromaeosauridae group . So far, two incomplete skeletons are known from the Upper Cretaceous of Mongolia come. The only species ( type species ) is Adasaurus mongoliensis . The sickle claw on the second (inner) toe of the foot, which is characteristic of dromaeosaurids, wassmallerin Adasaurus than in related genera and no larger than the other claws of the foot.
features
Adasaurus is estimated to be about 2.4 meters long and weigh about 36 kg. In contrast to other dromaeosaurids, the penultimate toe (phalange) of the second toe, which had the sickle claw, lacked asymmetrical crests. It is therefore assumed that the sickle claw may have had a different function in Adasaurus than in other dromaeosaurids. The hind legs appear very robust compared to other dromaeosaurids.
This genus shows some similarities with Velociraptor mongoliensis , another Mongolian dromaeosaurid: Both genera show a fused scapulocoracoid ( shoulder blade and raven bone ) and distal (lower) foot bones that are fused with the metatarsal bones. However, differences can be seen in some skull bones and in the pleurocoels (air-filled chambers) of the sacral vertebrae, which in Adasaurus were only present in the anterior sacral vertebrae. In addition to the reduced sickle claw , Adasaurus can be distinguished from other dromaeosaurids by features in the skull and pelvis: The frontal bone shows a flat dorsal ridge; In addition, the opening (foramen) of the surangular (a bone of the lower jaw) was relatively large. The pre-acetabular process of the ilium shows a notched anterior border.
Systematics
The systematic position within the Dromaeosauridae is controversial. Rinchen Barsbold assigned Adasaurus to the Dromaeosaurinae in his first description; a number of later authors followed this assignment. However, a more recent study by Currie and Longrich (2009) sees Adasaurus as a representative of the Velociraptorinae.
Finds, research history and naming
So far, two fragmentary skeletons are known that come from the Nemegt Formation , a rock unit in southwestern Mongolia. The holotype specimen (specimen number MPD 100/20) comes from the Bugin-Tsav site and consists of the back of the skull and the postcranium (residual skeleton); ribs, arms and some foot bones are missing. A second skeleton (copy number MPD 100/21) consists of the right foot and two caudal vertebrae. The fossils come from the early Maastrichtian and are therefore around 72 to 69 million years old.
The name Adasaurus first appeared in 1977 in a short publication by the famous Mongolian paleontologist Rinchen Barsbold ; but here the fossils are merely illustrated. In 1983 Rinchen Barsbold published a very brief description based on the two skeletons. In 2006, Kubota and Barsbold presented a re-examination of the fossils.
Rinchen Barsbold named the genus after Ada , an evil spirit from Mongolian mythology . The specific epithet mongoliensis points to the place where it was found, the country of Mongolia.
Individual evidence
- ↑ a b c d e f Katsuhiro Kubota, Rinchen Barsbold : Re-examination of Adasaurus mongoliensis (Dinosauria: Theropoda) from the Upper Cretaceous Nemegt Formation of Mongolia. In: Journal of Vertebrate Paleontology. Vol. 26, Supplement to No. 3 = Abstracts of Papers. Sixty-Sixth Annual Meeting Society of Vertebrate Paleontology. Canadian Museum of Nature. Marriott Ottawa, Crowne Plaza Ottawa, Ottawa, Ontario, Canada, October 18-21, 2006 , 2006, ISSN 0272-4634 , p. 88A, online (PDF; 6.0 MB) .
- ^ Alan H. Turner, Diego Pol, Julia A. Clarke, Gregory M. Erickson, Mark A. Norell : A Basal Dromaeosaurid and Size Evolution Preceding Avian Flight. In: Science . Vol. 317, No. 5843, 2007, pp. 1378-1381, doi : 10.1126 / science.1144066 , digitized version (PDF; 507.41 kB) , Supporting Online Material (PDF; 755.11 kB) .
- ↑ a b Mark A. Norell, Peter J. Makovicky : Dromaeosauridae. 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. 196-209.
- ↑ a b c Ринченгийн Барсболд: Хищные динозавры мела Монголии. Совместная Советско-Монгольская палеонтологическая экспедиция (= Труды. 19). Наука, Москва 1983, pp. 5–119 (In English: Rinchen Barsbold: Carnivorous dinosaurs from the Cretaceous of Mongolia. The Joint Soviet-Mongolian Paleontological Expedition (= Transaction of the Joint Soviet-Mongolian Paleontological Expedition. Vol. 19). Self-published by the author, Berkeley CA 1983, 5–119, online (PDF; 353 kB) ).
- ^ Adasaurus Taxonomy. In: The Paleobiology Database. Retrieved July 30, 2014 .
- ↑ Nicholas R. Longrich, Philip J. Currie : A microraptorine (Dinosauria – Dromaeosauridae) from the Late Cretaceous of North America. In: Proceedings of the National Academy of Sciences of the United States of America . Vol. 106, No. 13, 2009, pp. 5002-5007, doi : 10.1073 / pnas.0811664106 .
- ↑ Ринченгийн К. Барсболд: Эволюции Хищных Динозавров. In: Совместная советско-монгольская палеонтологическая экспедиция. Труды. Vol. 4, 1977, ISSN 0320-2305 , pp. 48-56.