一組恐龍化石提示,，羽毛和翼翅樣結(jié)構(gòu)首先是為了求偶而演化出的。大多數(shù)已知的羽毛得到良好保存的恐龍化石來(lái)自中國(guó),，但現(xiàn)在由Darla Zelenitsky及其同事所描述的化石則來(lái)自加拿大的阿爾伯塔,。研究人員分析了3具來(lái)自鴕鳥(niǎo)樣恐龍物種埃德蒙頓似鳥(niǎo)龍的骨架——2具幼年的和1具成年的骨架。所有3個(gè)樣品看來(lái)都覆蓋有短的,、絨毛樣的羽毛,，但只有該成年的樣品顯示了長(zhǎng)羽的證據(jù)——在其前肢上有著硬的中心軸。長(zhǎng)羽毛的延遲發(fā)育提示這些羽毛只是當(dāng)這些動(dòng)物在達(dá)到性成熟時(shí)才會(huì)使用,，也許用其來(lái)求偶,、炫耀或育雛。文章的作者提示,，羽毛只是在后來(lái)才添加了諸如體溫調(diào)節(jié)或飛行等其它的用途,。（生物谷Bioon.com）
doi: 10.1126/science.1225376
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Feathered Non-Avian Dinosaurs from North America Provide Insight into Wing Origins
Darla K. Zelenitsky, Francois Therrien, Gregory M. Erickson, Christopher L. DeBuhr, Yoshitsugu Kobayashi, David A. Eberth, and Frank Hadfield
Previously described feathered dinosaurs reveal a fascinating record of feather evolution, although substantial phylogenetic gaps remain. Here we report the occurrence of feathers in ornithomimosaurs, a clade of non-maniraptoran theropods for which fossilized feathers were previously unknown. The Ornithomimus specimens, recovered from Upper Cretaceous deposits of Alberta, Canada, provide new insights into dinosaur plumage and the origin of the avian wing. Individuals from different growth stages reveal the presence of a filamentous feather covering throughout life and winglike structures on the forelimbs of adults. The appearance of winglike structures in older animals indicates that they may have evolved in association with reproductive behaviors. These specimens show that primordial wings originated earlier than previously thought, among non-maniraptoran theropods.
