10月14日 - 科学家们发现了一种生活在中国约1.5亿年前、体型与乌鸦相当的鸟类化石，其翅膀发育不良，可能更擅长奔跑而非飞行 — — 这一发现描绘了早期鸟类演化更为复杂的图景。
Oct 14 - Scientists have discovered the fossil of a crow-sized bird that lived in China roughly 150 million years ago and possessed undersized wings that may have made it more of a runner than a flier — a discovery that paints a more complicated picture of early avian evolution.
这一新发现的侏罗纪时期物种，命名为越州鸟阳原种，是目前已知最早的鸟类之一，年代与欧洲著名的始祖鸟相近。越州鸟对早期鸟类而言十分 puzzling，因为它似乎已经为了在地面奔跑而削弱了飞行能力，或许有点像地面鹦鹉 — — 一种奔跑很快但飞行笨拙、很少腾空的鸟类。
The new Jurassic Period species, Yuezhuornis yangyuanensis, represents one of the earliest-known birds, similar in age to the famous Archaeopteryx from Europe. Yuezhuornis is puzzling for an early bird in that it seems already to have diminished the ability to fly in favor of running on the ground, perhaps somewhat like a roadrunner — a fast runner but clumsy flier that rarely takes to the air.
“越州鸟挑战了传统范式，即鸟类体型几乎完全是在飞行的选择压力下进化的，” 中国科学院古脊椎动物与古人类研究所的古生物学家王敏说道，他帮助领导了该研究，该研究于周三发表在《自然》杂志上。
"Yuezhuornis challenges the traditional paradigm that the avian body plan evolved almost exclusively under the selective pressures of flight," said paleontologist Min Wang of the Institute of Vertebrate Paleontology and Paleoanthropology, part of the Chinese Academy of Sciences, who helped lead the study published on Wednesday in the journal Nature.
“因此，这一新化石只是改变了我们对侏罗纪时期鸟类长相的假设，” 王敏说。
"So this new fossil just changes our assumption about what a Jurassic bird looks like," Wang said.
当被问及越州鸟是否可能像地面鹦鹉一样，主要通过奔跑生活，必要时才进行短距离飞行时，王敏说：“是的，这种可能性很大。” 这一几乎完整的化石是在中国东南部福建省出土的。
Asked if Yuezhuornis may have lived like a roadrunner by mostly running but flying in short bursts when necessary, Wang said, "Yes, that is likely." The nearly complete fossil was unearthed in Fujian Province in southeastern China.
鸟类是在侏罗纪时期从小型有羽毛恐龙演化而来的，但展示这一过程何时发生以及如何进行的化石却十分缺乏。始祖鸟长期被认为是已知最古老的鸟类，但如今发现了一些与它年代相近的其他鸟类，如越州鸟。
Birds evolved during the Jurassic from small feathered dinosaurs, but fossils showing precisely when this occurred and how it unfolded are lacking. Archaeopteryx long was the oldest-known bird but a small number of others of similar age like Yuezhuornis have now been found.
解剖特征的镶嵌组合 体重估计为1.8磅（800克）的岳州鸟，呈现出鸟类与恐龙特征相结合的镶嵌式解剖特征。其前肢已完全发育为翅膀，但与身体其他部位相比过小，无法支撑强健的飞行。它还拥有鸟类特有的纤细颅骨和类鸟骨盆。
MOSAIC OF ANATOMICAL TRAITS Yuezhuornis, which weighed an estimated 1.8 pounds (800 grams), presented a mosaic of anatomical traits combining avian and dinosaurian characteristics. Its forelimbs were fully developed wings, though they were too small compared to the rest of the body to have allowed for robust flying. It also had the slender cranial bones of a bird and a bird-like pelvis.
另一方面，岳州鸟灵活的第二脚趾上长有一枚镰刀状爪，这与恐爪龙、伶盗龙和伤齿龙等食肉恐龙相似——这是一种危险的武器，适合陆地猎手使用。事实上，王敏说，岳州鸟可能曾与小型非鸟恐龙争夺猎物。
On the other hand, Yuezhuornis had a sickle-shaped claw on its flexible second toe similar to that of meat-eating dinosaurs like Deinonychus, Velociraptor and Troodon — a dangerous weapon useful for a terrestrial hunter. In fact, Wang said, Yuezhuornis may have competed for prey with small non-bird dinosaurs.
它的颌骨上排列着相对较大、紧密且带锯齿的牙齿，这类特征通常见于某些食肉恐龙，而非鸟类。此外，它还拥有细长且由骨骼构成的恐龙式尾巴，这与所有已知最早的鸟类一样。
It had relatively large, closely packed and serrated teeth lining its jaws, typically present in certain carnivorous dinosaurs but not birds. In addition, it had a long and bony dinosaurian tail, as all the earliest-known birds did.
始祖鸟同样结合了鸟类与恐龙特征，但其匀称的翅膀显示它适合飞行。相比之下，岳州鸟的翅膀比腿短三分之一。与377种现生鸟类的对比显示，岳州鸟的肢体比例最类似于雉鸡等地栖鸟类。
Archaeopteryx combined avian and dinosaurian traits, too, but its well-proportioned wings showed it was built for flying. The wings of Yuezhuornis, by contrast, were a third shorter than its legs. Comparisons with 377 extant bird species showed that the limb proportions of Yuezhuornis most resembled those of ground-dwelling avian species like pheasants.
王敏说，岳州鸟被认为与始祖鸟共享一个生活在更早侏罗纪的共同祖先。王敏还说，岳朱鸟也可能代表一个独立于主要鸟类演化谱系之外的演化实验。
Yuezhuornis is believed to have shared with Archaeopteryx a common ancestor that lived earlier in the Jurassic, Wang said. It also is possible that Yuezhuornis represents an evolutionary experiment that emerged separately from the main avian evolutionary lineage, Wang said.
王敏说，他没想到会看到一种如此接近鸟类演化起源、却似乎只具备有限飞行能力甚至完全不会飞的物种。“这让我们感到惊讶，”王敏说。
Wang said he did not expect to see a species so close to the evolutionary origins of birds that appears to have possessed limited or perhaps no ability to fly. "It surprises us," Wang said.
爱丁堡大学古生物学家史蒂夫·布鲁萨特是恐龙和鸟类方面的专家，未参与该研究。他说：“越州鸟是那种提出的问题多于给出答案的发现之一。”布鲁萨特是最近出版的《鸟类的故事》一书的作者，该书探讨了鸟类的演化。他说，越州鸟似乎是鸟类演化谱系的实际成员。
University of Edinburgh paleontologist Steve Brusatte, an expert in dinosaurs and birds who was not involved in the study, said, "Yuezhuornis is one of those discoveries that throws up more questions than it gives answers." Brusatte, who authored the recent book "The Story of Birds" exploring avian evolution, said Yuezhuornis appears to be an actual member of the bird evolutionary lineage.
“这将使其既成为化石记录中最古老的鸟类之一，也成为鸟类家族树上最原始的鸟类之一。然而，这是一种奇怪的鸟类。它的骨骼看起来像是弗兰肯斯坦怪物的拼凑体，”布鲁萨特说，指的是鸟类和恐龙类的特征。
"That would make it both one of the oldest birds in the fossil record and one of the most primitive birds on the family tree. Yet this is a weird bird. Its skeleton looks like a Frankenstein monster mashup," Brusatte said, of avian and dinosaurian traits.
“它显然是一个重要的新物种，因为它表明早期鸟类及其最近的亲戚在解剖特征和体型方案上更加多样化和可变。但它也暗示，一些最早的鸟类可能并不是特别擅长飞行，甚至可能有些鸟类是从会飞的祖先进化而来，但又返回地面生活，很少甚至从未飞上天空，”布鲁萨特说。
"It's obviously an important new species because it shows that early birds and their closest relatives were more diverse and more variable in their anatomical features and body plans. But it also hints that some of the first birds were not particularly good fliers, maybe even that some of them had evolved from flying ancestors but reverted back to living on the ground, rarely if ever taking to the skies," Brusatte said.