Avimimus: Difference between revisions
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==Description== |
==Description== |
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''Avimimus'' was a small dinosaur, standing about 2.5 feet tall at the hips and a length of 1.5m (5ft). The skull was relatively small compared to the body, though the eyes and brain were relatively large. As in the related Oviraptoridae and Caenagnathidae, the jaws of Avimimus formed a parrot-like beak, and lacked teeth. However, a series of toothlike projections along the tip of the premaxilla would have given the beak a serrated edge. The neck was long and slender; the neck vertebrae are much more elongate than in other oviraptorosaurs. It also had three-toed feet with narrow pointed claws. Little is known of the tail but the hip suggests that the tail was long. |
''Avimimus'' was a small dinosaur, standing about 45cm(2.5 feet) tall at the hips and a length of 1.5m (5ft). The skull was relatively small compared to the body, though the eyes and brain were relatively large. As in the related Oviraptoridae and Caenagnathidae, the jaws of Avimimus formed a parrot-like beak, and lacked teeth. However, a series of toothlike projections along the tip of the premaxilla would have given the beak a serrated edge. The neck was long and slender; the neck vertebrae are much more elongate than in other oviraptorosaurs. It also had three-toed feet with narrow pointed claws. Little is known of the tail but the hip suggests that the tail was long. |
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Unlike oviraptorids and caenagnathids, the back vertebrae lack openings for air sacks, suggesting that ''Avimimus'' is more primitive than these animals. The forelimbs were relatively short. The bones of the hand were fused together, as in modern birds, and a ridge on the ulna (lower arm bone) was interpreted as an attachment point for feathers by Kurzanov.<ref name="kurzanov1981">Kurzanov, S.M. (1981). "An unusual theropod from the Upper Cretaceous of Mongolia Iskopayemyye pozvonochnyye Mongolii (Fossil Vertebrates of Mongolia)." ''Trudy Sovmestnay Sovetsko-Mongolskay Paleontologiyeskay Ekspeditsiy'' (''Joint Soviet-Mongolian Paleontological Expedition''), '''15''': 39-49. Nauka Moscow, 1981</ref> Kurzanov (1987) also reported the presence of [[quill knobs]],<ref name="kurzanov1987">Kurzanov, S.M. (1987). "Avimimidae and the problem of the origin of birds." ''Transactions of the Joint Soviet-Mongolian Paleontological Expedition'', '''31''': 5-92. [in Russian]</ref> and while Chiappe confirmed the presence of bumps on the ulna, their function remained unclear.<ref name="chiappe&witmer2002">Chiappe, L.M. and Witmer, L.M. (2002). ''Mesozoic Birds: Above the Heads of Dinosaurs.'' Berkeley: University of California Press, 536 pp. ISBN 0520200942</ref> The ilium was almost horizontally oriented, resulting in exceptionally broad hips. The legs were extremely long and slender, suggesting that ''Avimimus'' was a highly specialized runner. |
Unlike oviraptorids and caenagnathids, the back vertebrae lack openings for air sacks, suggesting that ''Avimimus'' is more primitive than these animals. The forelimbs were relatively short. The bones of the hand were fused together, as in modern birds, and a ridge on the ulna (lower arm bone) was interpreted as an attachment point for feathers by Kurzanov.<ref name="kurzanov1981">Kurzanov, S.M. (1981). "An unusual theropod from the Upper Cretaceous of Mongolia Iskopayemyye pozvonochnyye Mongolii (Fossil Vertebrates of Mongolia)." ''Trudy Sovmestnay Sovetsko-Mongolskay Paleontologiyeskay Ekspeditsiy'' (''Joint Soviet-Mongolian Paleontological Expedition''), '''15''': 39-49. Nauka Moscow, 1981</ref> Kurzanov (1987) also reported the presence of [[quill knobs]],<ref name="kurzanov1987">Kurzanov, S.M. (1987). "Avimimidae and the problem of the origin of birds." ''Transactions of the Joint Soviet-Mongolian Paleontological Expedition'', '''31''': 5-92. [in Russian]</ref> and while Chiappe confirmed the presence of bumps on the ulna, their function remained unclear.<ref name="chiappe&witmer2002">Chiappe, L.M. and Witmer, L.M. (2002). ''Mesozoic Birds: Above the Heads of Dinosaurs.'' Berkeley: University of California Press, 536 pp. ISBN 0520200942</ref> The ilium was almost horizontally oriented, resulting in exceptionally broad hips. The legs were extremely long and slender, suggesting that ''Avimimus'' was a highly specialized runner. |
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Revision as of 08:16, 3 April 2008
| Avimimus | |
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| File:Gondwana avimimus.jpg | |
| Mounted skeleton of Avimimus portentosus. | |
| Scientific classification | |
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| Family: | Avimimidae Kurzanov, 1981
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| Genus: | Avimimus Kurzanov, 1981
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| Species | |
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A. portentosus Kurzanov, 1981 (type) | |
Avimimus (Template:PronEng AY-vi-MYE-mus) meaning "bird mimic", because it resembled a bird (Latin avis = bird + mimus = mimic) was a genus of birdlike dinosaur that lived in the late Cretaceous in what is now Mongolia, around 75 million years ago.
Description
Avimimus was a small dinosaur, standing about 45cm(2.5 feet) tall at the hips and a length of 1.5m (5ft). The skull was relatively small compared to the body, though the eyes and brain were relatively large. As in the related Oviraptoridae and Caenagnathidae, the jaws of Avimimus formed a parrot-like beak, and lacked teeth. However, a series of toothlike projections along the tip of the premaxilla would have given the beak a serrated edge. The neck was long and slender; the neck vertebrae are much more elongate than in other oviraptorosaurs. It also had three-toed feet with narrow pointed claws. Little is known of the tail but the hip suggests that the tail was long. Unlike oviraptorids and caenagnathids, the back vertebrae lack openings for air sacks, suggesting that Avimimus is more primitive than these animals. The forelimbs were relatively short. The bones of the hand were fused together, as in modern birds, and a ridge on the ulna (lower arm bone) was interpreted as an attachment point for feathers by Kurzanov.[1] Kurzanov (1987) also reported the presence of quill knobs,[2] and while Chiappe confirmed the presence of bumps on the ulna, their function remained unclear.[3] The ilium was almost horizontally oriented, resulting in exceptionally broad hips. The legs were extremely long and slender, suggesting that Avimimus was a highly specialized runner.
The toothless beak of Avimimus suggests that it may have been an herbivore or omnivore.
Discovery and species
Its remains were discovered in the Djadokta Formation and officially described by Dr. Sergi Kurzanov in 1981. The type species is A. portentosus..[1]
In 1991, Sankar Chatterjee erected the Order Avimimiformes to include Avimimus, though this group is not used by most paleontologists today as it includes only a single species.
References
- ^ a b Kurzanov, S.M. (1981). "An unusual theropod from the Upper Cretaceous of Mongolia Iskopayemyye pozvonochnyye Mongolii (Fossil Vertebrates of Mongolia)." Trudy Sovmestnay Sovetsko-Mongolskay Paleontologiyeskay Ekspeditsiy (Joint Soviet-Mongolian Paleontological Expedition), 15: 39-49. Nauka Moscow, 1981
- ^ Kurzanov, S.M. (1987). "Avimimidae and the problem of the origin of birds." Transactions of the Joint Soviet-Mongolian Paleontological Expedition, 31: 5-92. [in Russian]
- ^ Chiappe, L.M. and Witmer, L.M. (2002). Mesozoic Birds: Above the Heads of Dinosaurs. Berkeley: University of California Press, 536 pp. ISBN 0520200942
