Tenontosaurus
| Tenontosaurus | ||||||||||||
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Tenontosaurus tilletti |
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| Temporal occurrence | ||||||||||||
| Lower Cretaceous ( Aptian to Middle Albian ) | ||||||||||||
| 126.3 to 107.5 million years | ||||||||||||
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| Scientific name | ||||||||||||
| Tenontosaurus | ||||||||||||
| Ostrom , 1970 | ||||||||||||
| Art | ||||||||||||
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Tenontosaurus ("lizard with tendons") was a dinosaur from the Iguanodontia group , which was common in the Lower Cretaceous ( Aptium to middle Albium ) in North America.
Two species have been described , the type Tenontosaurus tilletti of which about 27 skeletons were found in the Cloverly Formation in Montana and Wyoming and in the Paluxy Formation in Texas and Tenontosaurus dossi from the skull and skeletons of various individuals from the Twin Mountain Formation originate in Texas. In several places a specimen of Tenontosaurus was recovered together with several specimens of the predatory dinosaur Deinonychus .
features
Tenontosaurus was a medium-sized iguanodontid and reached a length of about seven meters, with its long tail making up almost two-thirds of the total length. The predentale , an additional bone in the lower jaw in front of the dentary that is only present in pelvic dinosaurs (Ornithischia) , is wedge-shaped when viewed from the side and horseshoe-shaped when viewed from above. There were tooth-like outgrowths on the Praedentale. It resembled the Praedentale more basal Euornithopoda . The dental had twelve teeth.
Tenontosaurus had 12 cervical, 16 trunk, 5 sacrum and 60 to 65 caudal vertebrae. The cervical vertebrae were slightly opisthocoel (concave on the back), the spinous processes were short. In fully grown specimens the vertebral centers of the sacrum and its ribs had grown together, in younger specimens they were still separated. The caudal vertebrae (proximal) towards the body had short and wide vertebrae and narrow spinous processes of low height that were bent forward. The vertebrae further back became longer.
Tenontosaurus kept its front legs mostly bent. The metacarpal bones were pressed flat at the upper end and arranged in a spread shape. The forefoot has the phalangeal formula 2.3.3.1 (? 2) .1 (? 2), the rear foot 2.3.5.5.0. Tenontosaurus therefore had five toes in front and four in back. The fifth metatarsal was reduced to a short, solitary bone. The extremities of the toes were narrow and pointed.
Systematics
Tenontosaurus was originally assigned to the Hypsilophodontidae , a taxon that is now considered paraphyletic . Tenontosaurus is currently considered to be the most basal iguanodontid . Of the two types is Tenontosaurus dossi the more original since it from the Aptian comes ( Tenontosaurus tilletti from the late Aptian to middle Albian ) and even one tooth on the premaxilla had.
literature
- David B. Norman : Basal Iguanodontia. In: David Weishampel , Peter Dodson , Halszka Osmólska : The Dinosauria . 2nd edition. University of California Press, Berkeley CA et al. 2004, ISBN 0-520-24209-2 , pp. 413-437.
Web links
- Comparisons to man (Engl.)
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. 280, online .