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Science and Technology
科技
Fossil feathers
羽毛化石
Not just for the birds
并非鳥類獨有
A trove of fossils sheds light on the evolution of feathers
珍貴羽毛化石的發現能夠更好地闡釋羽毛的進化過程
THE fossil record is, famously, full of holes.
眾所周知，化石記錄總是漏洞百出。
One such lacuna has been the absence of well-preserved feathers from the Cretaceous-the period between 145m and 65m years ago that ended with the mass extinction that wiped out the dinosaurs.
一個漏洞就是由于人們無法找到白堊紀時期保存完好的羽毛，因而該時期羽毛化石的記錄一直處于空白狀態。白堊紀是距今1.45億年到6500萬年的一段時期，末期發生了導致恐龍消失的物種大滅絕。
Now, this gap has been partly filled.
如今，這段空白得到了部分填充。
In this week's Science, a team led by Ryan McKellar from the University of Alberta report the discovery of eleven feathers preserved in amber from the latter part of the Cretaceous, about 70m-85m years ago.
本周，瑞安?麥凱樂領導的研究小組在《科學》雜志上發表報告稱，他們發現了11種白堊紀后期（距今約7000至8500萬年）封存在琥珀里的羽毛。
Intriguingly, not all of them seem to come from birds.
有趣的是，這些羽毛并不都屬于鳥類。
The origin of feathers is a mystery.
羽毛的起源一直是個謎。
The earliest known bird, Archaeopteryx, lived during the Jurassic, the period before the Cretaceous.
人類所熟知的最古老鳥類始祖鳥生活在白堊紀時期之前的侏羅紀時期。
But fossils from China suggest the precursors of feathers-simple, filament-like structures possibly used for insulation-evolved in land-lubbing dinosaurs and were only later adapted for flight.
中國出土的化石表明羽毛的前身呈簡易的絲狀結構，可能具有隔離熱量的功用，這些簡易絲狀羽毛在陸地恐龍身上不斷進化，直至后來才具備了飛行功能。
The top picture shows similar filaments discovered by Dr McKellar and his team, suggesting flightless dinosaurs sporting such protofeathers were still around in the late Cretaceous.
上圖所示為麥凱樂博士及其研究小組發現的類似絲狀的羽毛，表明長有這些原生羽毛的“非鳥”恐龍在白堊紀后期仍然存活著。
Not all the feathers found by Dr McKellar were so primitive, though.
不過，McKellar博士發現的羽毛并不都是遠古時代的。
The second picture shows one similar in shape to those sported by modern birds.
第二幅圖顯示的羽毛形狀與現代鳥類羽毛相似。
Modern feathers consist of thousands of fibres held together by tiny hooks.
現代鳥類羽毛由成千上萬束靠細鉤聚攏在一起的纖維構成。
The details of that design can be tweaked to change a feather's characteristics, offering waterproofing, insulation, streamlining and so on.
通過改進羽毛構造的細節可改變它的特性，如防水、隔熱、流線造型等功能。
The third picture shows feathers that have just such a specialisation: coiling reminiscent of that seen in the feathers of modern divers.
第三幅圖顯示的羽毛就具備這樣的特殊功能：螺旋造型與現代潛鳥的羽毛相似。
Such coiling allows a feather to absorb water, which streamlines and insulates the owner.
這種螺旋形狀的羽毛能夠吸水，并使該鳥類身形更加精巧同時起保溫作用。
These feathers, then, presumably adorned a diving bird-perhaps Hesperornis, a flightless North American diver from precisely this period.
這些羽毛想必當時是歸潛鳥所有——也許是“黃昏鳥”，一種恰好生活在這一時期不會飛翔的北美潛鳥。
The final picture shows pigmentation preserved in a fossil feather.
最后一幅圖顯示了封存在羽毛化石里的色素沉著。
Different feathers have different patterns of colour, suggesting that Cretaceous dinosaurs-flying or otherwise-used their feathers for display.
不同的羽毛有不同的顏色樣式，這表明白堊紀時期的會飛恐龍和陸地恐龍都利用羽毛來炫示自己。
Charles Darwin once said that contemplating a peacock's tail made him sick, such was the difficulty of explaining its complexity.
查爾斯?達爾文曾說過研究孔雀尾讓他有頭暈的感覺，可見想解釋清楚其復雜性有多難了。
Dr McKellar's finds suggest, at least, that that complexity began to evolve a long time ago.
不過，麥凱樂博士的發現至少表明這種復雜性在很久以前就開始進化了。
