Aralosaurus
| Aralosaurus | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Upper Cretaceous (late Campanium ) | ||||||||||||
| 76.4 to 72 million years | ||||||||||||
| Locations | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Aralosaurus | ||||||||||||
| Roshdestvensky , 1968 | ||||||||||||
Aralosaurus ("Lizard from the Aral Sea ") was a genus of ornithopod dinosaurs from the richly shaped group of hadrosaurs that existed during the Upper Cretaceous (late Campanium ) about 76 and 72 million years ago. The only species described is Aralosaurus tuberiferus .
Finds
Fossils of the genus were found in the Beleutinsk Formation in central Kazakhstan near the Aral Sea. The holotype with catalog number 2229/1 is a partially preserved skull. In the same horizon in which the holotype was found there were also some vertebrae, limb bones and individual teeth, which probably belonged to different specimens. However, the teeth are identical to those of the holotype and so one can assume that the other bones also belonged to Aralosaurus . In addition, the rear part of a very small right half of the lower jaw was found, which is 4.5 centimeters long and 3 centimeters high and must belong to a very young specimen.
features
The skull is moderately wide in the area of the zygomatic bone . The only partially preserved nasal bone rises at an almost right angle and then forms a downward arch. The frontal bone forms a very small part of the bony eye socket . The tear bone is very large. An elliptical fontanel delimits the nasal and frontal bones. The eye socket is larger than the infratemporal window and has the shape of an almost round oval. The fenestra supratemporalis is small. The posterior end of the postorbital bones terminate in three points. The os quadratum is curved on top. The maxillary is short and high, the premaxillary is not preserved. The upper jaw had a very broad tip and contained about 30 rows of teeth. There were about 20 small cusps on the front and back edges of each tooth. The teeth of the lower jaw had an additional row of cusps.
If you compare the skull length of 65 centimeters with that of other hadrosaurs, then Aralosaurus must have been about 6.5 meters long and was thus a medium-sized hadrosaur. The skull could have belonged to a young animal, however, as the bone sutures have not yet fully fused.
Systematics
Aralosaurus belongs to the Hadrosaurinae subfamily within the hadrosaurs, which did not have crests on their skulls. He is close to Bactrosaurus , Lophorhothon , and Kritosaurus . It differs from Bactrosaurus in the shape of the nasal bone, the smaller fenestra supratemporalis, the short, high jaw and the number of teeth. Differences from Lophorhothon are the small fenestra supratemporalis and the narrow fenestra infratemporalis and the larger number of teeth.
literature
- John R. Horner , David B. Weishampel , Catherine A. Forster: Hadrosauridae. 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. 438-463.
Individual evidence
- ^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ et al. 2010, ISBN 978-0-691-13720-9 , p. 306, online .