科學(xué)家剛剛發(fā)現(xiàn)了1.25億年前的恐龍頭皮屑

科學(xué)家剛剛發(fā)現(xiàn)了1.25億年前的恐龍頭皮屑

It's no secret dinosaurs possessed their own fair share of dirty habits—most bodies can get pretty gross, no matter the species. But dandruff? Nobody really saw that coming.

恐龍也有自己的骯臟習(xí)性，這不是什么秘密——不管什么物種，大多數(shù)身體都會變得很惡心。但頭皮屑?沒有人真正預(yù)見到這一點。

A new study published in Nature Communications illustrates the discovery of some 125 million-year-old dinosaur dandruff fossils. The findings aren't just a quick excuse for making a bad Head and Shoulders quip, but also actually explain a mechanism by which dinosaurs did something nearly universal: shed skin.

發(fā)表在《自然通訊》(Nature Communications)雜志上的一項新研究表明，發(fā)現(xiàn)了大約1.25億年前的恐龍頭皮屑化石。這些發(fā)現(xiàn)不僅僅是一個快速的借口，用來諷刺糟糕的頭和肩膀，而且實際上也解釋了恐龍是如何做一些幾乎普遍的事情的:蛻皮。

“Probably nobody much thought about how dinosaurs shed their skin before,” says Mike Benton, a professor of vertebrate paleontology at the University of Bristol and a coauthor of the new study. The new findings “tell us that dinosaurs were like birds, shedding their skin in small flakes.”

布里斯托爾大學(xué)脊椎動物古生物學(xué)教授、這項新研究的合著者邁克•本頓(Mike Benton)說：“以前可能沒人想過恐龍是如何蛻皮的。新的發(fā)現(xiàn)告訴我們恐龍就像鳥一樣，把皮膚剝落成小塊。”

The findings stem from the analysis of feathers from the Cretaceous period in China, from three different dinosaur species (Microraptor, Beipiaosaurus, and Sinornithosaurus) and the early bird Confuciusornis. Benton and his colleagues had been working with the specimens since 2007, and the characterization of the skin flakes is just their latest milestone.

這些發(fā)現(xiàn)源于對中國白堊紀(jì)時期、三種不同的恐龍(小盜龍、北票龍和中華鳥龍)和早期鳥類孔子鳥的羽毛的分析。本頓和他的同事們從2007年就開始研究這些樣本，對皮膚薄片的鑒定只是他們的最新里程碑。

All animals molt, or rid themselves of old skin and feathers and hair, so they can grow larger and new face environmental challenges with a fresh new coat of exterior tissue. Before the new findings, there was a dearth in understanding how dinosaur skin worked and how the mighty beasts managed to shed it. The most prevalent theory was that molting in dinosaurs occurred in pieces, as it does in their closest modern relatives (birds and crocodiles). The whole-sheath skin shedding technique used by snakes and some lizards would have made less sense for dinosaurs, given that these species are more distantly related.

所有的動物都會蛻皮，或者去掉舊的皮膚、羽毛和毛發(fā)，這樣它們就能長得更大，新的外部組織也會面臨新的環(huán)境挑戰(zhàn)。在這些新發(fā)現(xiàn)之前，人們對恐龍的皮膚是如何工作的，以及這些強大的動物是如何擺脫皮膚的，還缺乏了解。最流行的理論是，恐龍的蛻皮是碎片化的，就像它們最近的現(xiàn)代親戚(鳥類和鱷魚)一樣。蛇和一些蜥蜴使用的全皮脫落技術(shù)對恐龍來說意義不大，因為這些物種的親緣關(guān)系較遠(yuǎn)。

But during the group's work using regular and electron microscopes, the researchers kept coming across strange white blobs located all over the plumage. Upon further investigation using ion beam microscope (which revealed the internal structure of the flakes), the team identified the specks as corneocytes: tough cells composed of twisted fibers of keratin, found in both modern birds as well as human dandruff.

但在研究小組使用常規(guī)顯微鏡和電子顯微鏡的工作中，研究人員不斷發(fā)現(xiàn)羽毛上到處都是奇怪的白色斑點。在進一步使用離子束顯微鏡(揭示了薄片的內(nèi)部結(jié)構(gòu))進行研究后，研究小組確定了這些斑點為角質(zhì)細(xì)胞：由扭曲的角蛋白纖維組成的堅韌細(xì)胞，在現(xiàn)代鳥類和人類頭皮屑中都有發(fā)現(xiàn)。

“We avoided the word dandruff in the scientific paper since it’s a term usually applied to skin flakes between the hair of humans,” says Benton. “But this is what we’re seeing, trapped between shafts of feathers in the fossil birds and dinosaurs. They are tiny flakes of surface skin, measuring 1 to 2 millimeters across.” The team believes dandruff probably evolved during the Middle Jurassic period, during which there was a bloom in new feathery dinosaur species.

本頓說：“我們在科學(xué)論文中避免使用頭皮屑這個詞，因為它通常用于人類頭發(fā)之間的皮膚薄片。”。“但這正是我們所看到的，困在鳥類化石和恐龍羽毛之間。研究小組認(rèn)為，頭皮屑可能是在中侏羅紀(jì)時期進化而來的，在這一時期，新的羽毛恐龍物種大量繁殖。

Beyond the fact that apparently dinosaurs would be embarrassed to wear black clothing without a good head scrub, the detail of the skin structure from the fossil shows us the species studied “were warm-blooded, but not as greatly as modern birds,” says Benton. Flying can produce enormous amounts of metabolic heat, and modern day birds use skin shedding as way facilitate evaporative cooling. The dinos, in contrast, possess more tightly packed corneocytes that are not as freely shed, so cooling through this mechanism would have been more limited. This suggests these dinosaurs probably generated lower amounts of heat during flight, if they could fly at all.

本頓說，除了顯然恐龍會因為沒有良好的頭部擦洗而穿黑色衣服而感到尷尬之外，化石上的皮膚結(jié)構(gòu)細(xì)節(jié)還告訴我們，所研究的物種“是溫血動物，但沒有現(xiàn)代鳥類大。”。飛行會產(chǎn)生大量的代謝熱，現(xiàn)代鳥類利用皮膚脫落來促進蒸發(fā)冷卻。相比之下，恐龍擁有更緊密的角質(zhì)細(xì)胞，而這些細(xì)胞并沒有自由脫落，因此通過這種機制進行冷卻會受到更大的限制。這表明這些恐龍在飛行過程中產(chǎn)生的熱量可能更低，如果它們能夠飛行的話。

Danny Barta, a comparative biology researcher at the American Museum of Natural History who was not involved with the study, calls the findings “groundbreaking, particularly because we’ve never had such clear insight into the skin of feathered dinosaurs before.”

美國自然歷史博物館(American Museum of Natural History)的比較生物學(xué)研究員丹尼·巴塔(Danny Barta)沒有參與這項研究，他稱這一發(fā)現(xiàn)是“開創(chuàng)性的，特別是因為我們以前從未對有羽毛恐龍的皮膚有過如此清晰的認(rèn)識。”

“The study confirms yet another shared feature between non-avian dinosaurs and birds, and it’s particularly exciting to see these similarities emerge in most regions of the anatomy, all the way down to the microstructural level,” Barta says.

巴塔說：“這項研究證實了非鳥類恐龍和鳥類之間的另一個共同特征，尤其令人興奮的是，這些相似之處出現(xiàn)在解剖學(xué)的大部分區(qū)域，一直到微觀結(jié)構(gòu)層面。”。

Moving forward, Benton and his team want to extend their study of feathers and skin to other dinosaur specimens and see how common these features are, especially in species that are more closely related to modern birds. But personally, I'm hoping this paper is just the first in a new field of study focused on bad dinosaur hygiene—and that the results make it into the third "Jurassic World" movie.

接下來，本頓和他的團隊希望將他們對羽毛和皮膚的研究擴展到其他恐龍標(biāo)本，看看這些特征有多普遍，特別是在與現(xiàn)代鳥類關(guān)系更密切的物種中。但就我個人而言，我希望這篇論文只是第一篇針對恐龍衛(wèi)生不良的新研究領(lǐng)域的論文，并希望其成果能成為第三部《侏羅紀(jì)世界》電影。