Фото со стока — Microraptor

DinoZavro.ru — Энциклопедия динозавров

Description

Wingspan and body size compared with a human

With adult specimens estimated up to 77 centimetres long (2.53 ft) and with a weight estimated up to 1 kilogram (2.2 lb), Microraptor was among the smallest-known non-avian dinosaurs. Holtz estimated it at 90 centimetres (3.0 ft). An estimate by Benson et al. in 2012 was that Microraptor had a maximum length of 1.2 m (3.9 ft). Aside from their extremely small size, Microraptor were among the first non-avialan dinosaurs discovered with the impressions of feathers and wings. Seven specimens of M. zhaoianus have been described in detail, from which most feather impressions are known. Unusual even among early birds and feathered dinosaurs, Microraptor is one of the few known bird precursors to sport long flight feathers on the legs as well as the wings. Their bodies had a thick covering of feathers, with a diamond-shaped fan on the end of the tail (possibly for added stability during flight). Xu et al. (2003) compared the longer plumes on Microraptor‘s head to those of the Philippine eagle. Bands of dark and light present on some specimens may indicate color patterns present in life, though at least some individuals almost certainly possessed an iridescent black coloration. Several anatomical features found in Microraptor, such as a combination of unserrated and partially serrated teeth with constricted ‘waists’, and unusually long upper arm bones, are shared with both primitive avians and primitive troodontids. Microraptor is particularly similar to the basal troodontid Sinovenator; in their 2002 description of two M. zhaoianus specimens, Hwang et al. note that this is not particularly surprising, given that both Microraptor and Sinovenator are very primitive members of two closely related groups, and both are close to the deinonychosaurian split between dromaeosaurids and troodontids.

Coloration

Restoration of M. gui with coloration based on fossilized melanosomes

In March 2012, Quanguo Li et al. determined the plumage coloration of Microraptor based on the new specimen BMNHC PH881, which also showed several other features previously unknown in Microraptor. By analyzing the fossilized melanosomes (pigment cells) in the fossil with scanning electron microscope techniques, the researchers compared their arrangements to those of modern birds. In Microraptor, these cells were shaped in a manner consistent with black, glossy coloration in modern birds. These rod-shaped, narrow melanosomes were arranged in stacked layers, much like those of a modern starling, and indicated iridescence in the plumage of Microraptor. Though the researchers state that the true function of the iridescence is yet unknown, it has been suggested that the tiny dromaeosaur was using its glossy coat as a form of communication or sexual display, much as in modern iridescent birds.

References

1. ^ Senter, P.; Barsold, R.; Britt, B.B.; Burnham, D.A. (2004). «Systematics and evolution of Dromaeosauridae (Dinosauria, Theropoda)». Bulletin of the Gunma Museum of Natural History. 8: 1–20.
2. ^
3. ^
4. ^
5. ^ Benson, R.B.J. & Brussatte, S. (2012). Prehistoric Life. London: Dorling Kindersley. p. 332. ISBN 978-0-7566-9910-9.
6. ^ Hwang, S.H., Norell, M.A., Ji, Q., and Gao, K. (2002). «New Specimens of Microraptor zhaoianus (Theropoda: Dromaeosauridae) from Northeastern China.» American Museum Novitates, 3381: 44pp.
7. ^
8. ^
9. ^ Xu, X., Zhou, Z., Wang, X., Kuang, X., Zhang, F. and Du, X. (2003). «Four-winged dinosaurs from China.» Nature, 421(6921): 335-340, 23 Jan 2003.
10. ^
11. Senter, P (2006). «Scapular orientation in theropods and basal birds, and the origin of flapping flight». Acta Palaeontol. Pol. 51: 305–313.
12. ^
13. Beebe, C. W. A. (1915). «Tetrapteryx stage in the ancestry of birds». Zoologica. 2: 38–52.
14. Larsson, Hans, Hone, David, Dececchi, T. Alexander, Sullivan, Corwin, Xu, Xing. «THE WINGED NON-AVIAN DINOSAUR MICRORAPTOR FED ON MAMMALS: IMPLICATIONS FOR THE JEHOL BIOTA ECOSYSTEM» «Program and Abstracts. 70th Anniversary Meeting Society of Vertebrate Paleontology October 2010» 114A.
15. ^
16. ^
17. Olson, S.L. (2000). «Countdown to Piltdown at National Geographic: the rise and fall of Archaeoraptor.» Backbone, 13(2) (April): 1–3.
18. Xu, X., Zhou, Z., and Wang, X. (2000). «The smallest known non-avian theropod dinosaur.» Nature, 408 (December): 705-708.
19. ^ Norell, Mark, Ji, Qiang, Gao, Keqin, Yuan, Chongxi, Zhao, Yibin, Wang, Lixia. (2002). «‘Modern’ feathers on a non-avian dinosaur». Nature, 416: pp. 36. 7 March 2002.>
20. ^ Czerkas, Sylvia J. ed. (2002) «Feathered Dinosaurs and the Origin of Flight» The Dinosaur Museum Journal Volume 1. Blanding, Utah, USA. The Dinosaur Museum, August 1, 2002
21. ^