科学家刚刚发现了1.25亿年前的恐龙头皮屑

科学家刚刚发现了1.25亿年前的恐龙头皮屑

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.

恐龙也有自己的肮脏习性，这不是什么秘密——不管什么物种，大多数身体都会变得很恶心。但头皮屑?没有人真正预见到这一点。

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.

发表在《自然通讯》(Nature Communications)杂志上的一项新研究表明，发现了大约1.25亿年前的恐龙头皮屑化石。这些发现不仅仅是一个快速的借口，用来讽刺糟糕的头和肩膀，而且实际上也解释了恐龙是如何做一些几乎普遍的事情的:蜕皮。

“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.”

布里斯托尔大学脊椎动物古生物学教授、这项新研究的合著者迈克•本顿(Mike Benton)说：“以前可能没人想过恐龙是如何蜕皮的。新的发现告诉我们恐龙就像鸟一样，把皮肤剥落成小块。”

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.

这些发现源于对中国白垩纪时期、三种不同的恐龙(小盗龙、北票龙和中华鸟龙)和早期鸟类孔子鸟的羽毛的分析。本顿和他的同事们从2007年就开始研究这些样本，对皮肤薄片的鉴定只是他们的最新里程碑。

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.

所有的动物都会蜕皮，或者去掉旧的皮肤、羽毛和毛发，这样它们就能长得更大，新的外部组织也会面临新的环境挑战。在这些新发现之前，人们对恐龙的皮肤是如何工作的，以及这些强大的动物是如何摆脱皮肤的，还缺乏了解。最流行的理论是，恐龙的蜕皮是碎片化的，就像它们最近的现代亲戚(鸟类和鳄鱼)一样。蛇和一些蜥蜴使用的全皮脱落技术对恐龙来说意义不大，因为这些物种的亲缘关系较远。

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.

但在研究小组使用常规显微镜和电子显微镜的工作中，研究人员不断发现羽毛上到处都是奇怪的白色斑点。在进一步使用离子束显微镜(揭示了薄片的内部结构)进行研究后，研究小组确定了这些斑点为角质细胞：由扭曲的角蛋白纤维组成的坚韧细胞，在现代鸟类和人类头皮屑中都有发现。

“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.

本顿说：“我们在科学论文中避免使用头皮屑这个词，因为它通常用于人类头发之间的皮肤薄片。”。“但这正是我们所看到的，困在鸟类化石和恐龙羽毛之间。研究小组认为，头皮屑可能是在中侏罗纪时期进化而来的，在这一时期，新的羽毛恐龙物种大量繁殖。

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.

本顿说，除了显然恐龙会因为没有良好的头部擦洗而穿黑色衣服而感到尴尬之外，化石上的皮肤结构细节还告诉我们，所研究的物种“是温血动物，但没有现代鸟类大。”。飞行会产生大量的代谢热，现代鸟类利用皮肤脱落来促进蒸发冷却。相比之下，恐龙拥有更紧密的角质细胞，而这些细胞并没有自由脱落，因此通过这种机制进行冷却会受到更大的限制。这表明这些恐龙在飞行过程中产生的热量可能更低，如果它们能够飞行的话。

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.”

美国自然历史博物馆(American Museum of Natural History)的比较生物学研究员丹尼·巴塔(Danny Barta)没有参与这项研究，他称这一发现是“开创性的，特别是因为我们以前从未对有羽毛恐龙的皮肤有过如此清晰的认识。”

“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.

巴塔说：“这项研究证实了非鸟类恐龙和鸟类之间的另一个共同特征，尤其令人兴奋的是，这些相似之处出现在解剖学的大部分区域，一直到微观结构层面。”。

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.

接下来，本顿和他的团队希望将他们对羽毛和皮肤的研究扩展到其他恐龙标本，看看这些特征有多普遍，特别是在与现代鸟类关系更密切的物种中。但就我个人而言，我希望这篇论文只是第一篇针对恐龙卫生不良的新研究领域的论文，并希望其成果能成为第三部《侏罗纪世界》电影。