Apsaravis
Apsaravis | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Clade: | Avialae |
Clade: | †Ambiortiformes |
Genus: | †Apsaravis Norell & Clarke, 2001 |
Species: | †A. ukhaana
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Binomial name | |
†Apsaravis ukhaana Norell & Clarke, 2001
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Apsaravis is a
Its habitat was presumably very
Implications
Apsaravis is important in avian paleontology. It has provided evidence that is directly relevant to at least four issues:
Sauriurae
The
Enantiornithine monophyly
In their cladistic analyses, Clarke and Norell (2002) found that Apsaravis had a mixture of primitive and advanced characters (described above in "Sauriurae") that removed most of the supporting characters for the clade
Ecological bottle neck
Prior to the discovery of Apsaravis, most ornithurine birds had been found in marine, lacustrine, or littoral sediments. This led Feduccia (1996)[4] and Martin (1983)[2] to deduce that the ancestors of modern birds were restricted to aquatic environments, and that they were all basal members of the Charadriiformes. Because they believed that all such birds had a "shorebird ecology", they described this limited habitat as an "ecological bottleneck", with all other ecological niches being dominated by enantiornithine birds instead. Apsaravis, however, was found in a sand dune environment, and it has no obviously aquatic anatomical adaptations, giving clear evidence that not all early members of Ornithurae were shorebirds.[3]
Automatic extension of the manus
Apsaravis is the most basal bird that possesses an extensor process. This is a bony projection on metacarpal I that develops at the insertion of the m.extensor metacarpi radialis muscle and the propatagial ligaments. This anatomy functions to "automate" extension of the
Phylogenetic position
Clarke and Norell (2002) found that Apsaravis is the most basal ornithurine bird, but more advanced than Enantiornithes and Patagopteryx.[3]
Subsequent
Footnotes
- ^ Norell, Mark A., Clarke, Julia A. (2001). "Fossil that fills a critical gap in avian evolution". Nature Vol. 409 11 January 2001 pp.181-184.
- ^ a b Martin, Larry D. (1983). "The origin and early radiation of birds" pp.291-338 in Perspectives on Ornithology Brush, A.H., Clark, G.A. New York: Cambridge University Press
- ^ a b c d e Clarke, Julia A., Norell, Mark A. (2002). "The morphology and phylogenetic position of Apsaravis ukhaana from the Late Cretaceous of Mongolia". American Museum Novitates, No. 3387, American Museum of Natural History, New York, NY.
- ^ Feduccia, Alan (1996). The origin and evolution of birds. New Haven, CT: Yale University Press. 420pp.
References
- Mortimer, Michael (2004): The Theropod Database: Phylogeny of taxa. Retrieved 2013-MAR-02.