Sharovipteryx
| Sharovipteryx Temporal range: Middle Triassic-Late Triassic, 230–225 Ma |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Infraclass: | Archosauromorpha |
| Order: | Prolacertiformes |
| Family: | Sharovipterygidae Tatarinov, 1989 |
| Genus: | Sharovipteryx Cowen, 1981 |
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Sharovipteryx ("Sharov's wing", known until 1981 as Podopteryx, "foot wing"), was an early gliding reptile, from the middle-late Triassic period (230-225 million years ago). Fossils have been found from the Madygen Formation of Kyrgyzstan along with the unusual reptile Longisquama. It was approximately eight inches (20 cm) long, with an extremely long tail, and weighed about 7.5 grams. It may have been closely related — or perhaps even ancestral — to pterosaurs,[1] although this remains controversial. Unlike pterosaurs, its main flight membrane was stretched between long back legs rather than its very short front limbs.
If Sharovipteryx was a relative of pterosaurs, then its membrane may have stretched to its front legs, or it may have had a separate membrane joined to its front limbs alone. A secondary membrane is visible between the thighs and the trunk. Front wing membranes have not been seen; Peters (2006) has claimed to have traced the fingers[2] and that they show similarities to Cosesaurus and Longisquama and to a lesser extent, pterosaurs. Some scenarios have it as a leaping animal, which would spring up in the air and then control its fall with its "wings". This fits well with the belief that pterosaurs evolved from running, leaping ancestors, because some scientists believe they lacked adaptations for living in trees. However, others suggest that Sharovipteryx would run up a tree on its sharply clawed rear legs (its overall design seems poor for climbing), and then spring into the air. The forelimbs seem too short for quadrupedal running or climbing. Such a configuration was probably necessary in order to free the forelimbs from the task of walking and allow them to become something else.
Sharovipteryx was a biped. Compared to e.g. living lizards capable of bipedal running, Sharovipteryx had a better pelvis, more sacral vertebrae, longer hind limbs, a shorter torso and a thinner tail. The diminution of the tail muscles and the increase in the pelvic muscles might show that Sharovipteryx was on its way toward a pterosaur-like metabolism, probably homeothermic. It was not depending on torso undulations for locomotion and therefore not subject to Carrier's constraint on breathing while running.
In 2006, Dyke et al.[3] published a study on possible gliding techniques for Sharovipteryx. The authors found that the wing membrane, which stretched between its very long hind legs and tail, would have allowed it to glide in a manner similar to delta wing aircraft. If the tiny front limbs also supported a membrane, they could have acted as a very efficient means of controlling pitch stability, very much like a canard. Without a forewing, the authors find, controlled gliding would have been very difficult (unfortunately, the area around the forelimbs was completely prepared away in the only known fossil, destroying any possible trace of a membrane there). Together with the canards on the forelimbs, these anterior membranes may have formed excellent control surfaces for gliding.
Sharov in 1971[4] illustrated the finger tips to the elongated digit IV in both hands.
[edit] References
- ^ Peters, D., 2000. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. - Rivista Italiana di Paleontologia e Stratigrafia 106(3): 293-336
- ^ Peters, D. (2006). "The Front Half of Sharovipteryx" Prehistoric Times 76: 10-11.
- ^ Dyke, G.J., Nudds, R.L. and Rayner, J.M.V. (2006). "Flight of Sharovipteryx mirabilis: the world's first delta-winged glider." Journal of Evolutionary Biology.
- ^ Sharov, A.G. 1971. New flying reptiles from the Mesozoic of Kazakhstan and Kirghizia. - Transactions of the Paleontological Institute, Akademia Nauk, USSR, Moscow, 130: 104–113 [in Russian].
[edit] External links
- First Delta-Wing Fighter Was a Reptile - LiveScience.com
- JPG of the fossil from the Russian paleontological museum - Paleo.ru
