一項(xiàng)新的研究報(bào)告說,，一個(gè)3500萬年前的企鵝的羽毛化石披露了某些現(xiàn)代特質(zhì)的線索,。 在現(xiàn)代鳥類的羽毛中所發(fā)現(xiàn)的被稱作黑色素體的色素顆粒在鳥羽化石中首次報(bào)導(dǎo)的時(shí)間是在2008年,。
這些色素顆粒非常細(xì)小,，人的毛發(fā)直徑可容納一百個(gè)黑色素體,。 如今,，Julia Clarke及其同事證明，化石化的黑色素體可確定企鵝的演化發(fā)展,。 企鵝高度適應(yīng)其寒冷的水生環(huán)境,。 它們的翅膀和羽毛的變化使得它們能夠快速地游泳（水中“飛行”）并保護(hù)它們?cè)诮鮾鼋Y(jié)的水中不受傷害；然而,，解釋企鵝羽毛是如何演化的數(shù)據(jù)則非常少。 在本研究中,，研究人員對(duì)一個(gè)在秘魯發(fā)現(xiàn)的羽毛得到完好保存的3500萬年前的企鵝進(jìn)行了分析,。 盡管遠(yuǎn)古企鵝的翅膀和羽毛的外觀與當(dāng)今企鵝的相似，但該研究團(tuán)隊(duì)發(fā)現(xiàn),，其羽毛中的黑色素體則與當(dāng)今企鵝的并不一樣,。
明確地說，遠(yuǎn)古企鵝的色素細(xì)胞與許多其它水鳥的色素細(xì)胞類似,，但卻與當(dāng)今企鵝的色素細(xì)胞不同,。 這些結(jié)果提示，遠(yuǎn)古企鵝羽毛的形狀和構(gòu)成在影響諸如力量和水阻力等性質(zhì)的微觀變化之前就已經(jīng)演化了,，這也許對(duì)解釋企鵝是如何及何時(shí)適應(yīng)于水中生活的有所幫助,。（生物谷Bioon.com）
生物谷推薦英文摘要：
Science DOI: 10.1126/science.1193604
Fossil Evidence for Evolution of the Shape and Color of Penguin Feathers
Julia A. Clarke,1,* Daniel T. Ksepka,2,3 Rodolfo Salas-Gismondi,4 Ali J. Altamirano,4 Matthew D. Shawkey,5 Liliana D’Alba,5 Jakob Vinther,6 Thomas J. DeVries,7 Patrice Baby8,9
Penguin feathers are highly modified in form and function, but there have been no fossils to inform their evolution. A giant penguin with feathers was recovered from the late Eocene (~36 million years ago) of Peru. The fossil reveals that key feathering features including undifferentiated primary wing feathers and broad body contour feather shafts evolved early in the penguin lineage. Analyses of fossilized color-imparting melanosomes reveal that their dimensions were similar to those of nonpenguin avian taxa and that the feathering may have been predominantly gray and reddish-brown. By contrast, the dark black-brown color of extant penguin feathers is generated by strikingly large, ellipsoidal melanosomes previously unknown for birds. The nanostructure of penguin feathers was thus modified after earlier macrostructural modifications of feather shape linked to aquatic flight.
1 Department of Geological Sciences, University of Texas at Austin, Austin, TX 78712, USA.
2 Department of Marine, Earth and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695–8208, USA.
3 Department of Paleontology, North Carolina Museum of Natural Sciences, Raleigh, NC 27601–1029, USA.
4 Departamento de Paleontología de Vertebrados, Museo de Historia Natural-UNMSM, Lima 14, Perú.
5 Integrated Bioscience Program, University of Akron, Akron, OH 44325, USA.
6 Department of Geology and Geophysics, Yale University, New Haven, CT 06511, USA.
7 Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA.
8 IRD; LMTG; 14 Av. Edouard Belin, F-31400 Toulouse, France.
9 Université de Toulouse; UPS; LMTG; F-31400 Toulouse, France.
