【经济学人】恐龙要革命丨2017.03.27丨总第853期

AS EVERY school-aged aficionado of dinosaurs knows, those terrible reptiles are divided into two groups: the Saurischia and the Ornithischia —or, to people for whom that is all Greek, the lizard-hipped and the bird-hipped. The names go back 130 years, to 1887, when they were invented and applied by Harry Seeley, a British palaeontologist .

提到恐龙这种恐怖爬行动物的生物学分类，对于恐龙爱好者（哪怕是学龄前儿童）来说，都可谓手到拈来：恐龙分为蜥臀目与鸟臀目（来自希腊语的Saurischia和Ornithischia）两大类，这两个名称来自130年前，由英国古生物学家HSeeley在1887年发明并使用。

• Aficionado：n. 迷；狂热爱好者

• Reptile：n. 爬行动物

• Saurischia：n. 蜥臀目

• Ornithischia：n. 鸟臀目

• Palaeontologist：n. 古生物学者

Seeley determined that the arrangement of the bones in a dinosaur’s pelvis —specifically, whether the pubic bone points forwards (Saurischia) or backwards (Ornithischia)—could be used to assign that species to one of these two groups. In his view, and that of subsequent palaeontologists, the evolution of other features of dinosaur skeletons supported the idea that these two hip-defined groups were what are now referred to as clades , each having a single common ancestor . Seeley thereby thought he had overthrown the dinosaurs as a true clade themselves: he believed Saurischia and Ornithischia were descended separately from a group called the thecodonts .

Seeley发现可以利用恐龙骨盆部位的骨骼结构来将恐龙分为两类：耻骨前凸的为蜥臀目，耻骨向后延伸的为鸟臀目。在他和其后的古生物学家看来，恐龙骨骼其他特征的演化可以证明，这两种根据骨盆定义的分类体现了如今所说的进化枝， 即物种来自单一的共同祖先。因此，Seeley认为他推翻了“恐龙是一个真正进化枝”的理论，他相信蜥臀目与鸟臀目是从槽齿目的并系群分别演来。

• Pelvis：n. 骨盆

• Pubic bone：n. 耻骨

• Clade：n. 分化枝；进化枝

• Ancestor：n. 始祖，祖先

• Thecodont：adj. 有槽齿的；槽齿类的

Subsequent analysis suggests he was wrong about that. The dinosaurs do seem to be a proper clade, with a single thecodont ancestor. But the basic division Seeley made of them, into Saurischia and the Ornithischia, has not been challenged—until now.

此后的分析研究表明，他的观点并不正确。恐龙好像确实是拥有单一槽齿目祖先的完整进化枝。但他提出的蜥臀目-鸟臀目基本分类方式直到现在都无人质疑。

The challengers are Matthew Baron, of Cambridge University, and his colleagues. Writing in Nature, they suggest dinosaur classification needs to be shaken up. Their system still has two groups, but it looks very different from Seeley’s.

挑战者是牛津大学的Matthew Baron及其同僚。他们在《自然》杂志中刊文称，需要重新为恐龙分类。他们提出的方案依然将恐龙分为两类，但与Seeley的方式大相径庭。

Based on an analysis of 74 types of dinosaurs and close relatives of dinosaurs, which examined 457 skeletal characteristics, they propose that hip-structure is not the be-all and end-all that Seeley and his successors thought it was. Instead, they separate the two great subgroups of Saurischia, the sauropods ( Brontosaurus , Diplodocus , etc) and the theropods ( Tyrannosaurus , Allosaurus , etc) and reassign them. The sauropods are teamed up with a group called the Herrerasauridae, which are so primitive they are not easily fitted into the Saurischia-Ornithischia system, to form a reconstituted Saurischia. The rest of the Ornithischia and the theropods, meanwhile, are joined as a newly named group, the Ornithoscelida.

在对74种恐龙和恐龙近亲的457块骨骼进行特征分析后，他们对Seeley 及其继任者们的理论提出质疑，认为光凭骨盆结构并不能对恐龙进行严谨且全面的分类。他们对蜥臀目的两大子类——蜥脚亚目（雷龙和梁龙等）和兽脚亚目（暴龙和异龙等）进行了重新划分，将蜥脚亚目与极为古老且难以在蜥臀目-鸟臀目系统中分类的艾雷拉龙下目分为一类，构成新的蜥臀目；其余的鸟臀目和兽脚亚目合并成为一个新类别，取名为Ornithoscelida（译者注：爬行动物和鸟类之间的中间结构，尤其考虑到骨盆）。

• Sauropod：n. 蜥脚亚目恐龙

• Brontosaurus：n. 雷龙

• Diplodocus：n. 梁龙

• Theropod：n. 兽脚亚目恐龙

• Tyrannosaurus：n. 暴龙

• Allosaurus：n. 异龙

• Herrerasauridae：n. 艾雷拉龙下目

• Primitive：adj. 原始的，远古的；简单的，粗糙的

鸟臀目解剖特征

Whether Dr Baron’s classification will hold up remains to be seen. Any system based on comparative anatomy rather than DNA is vulnerable to the evolution of similar features on separate occasions—giving an illusion of relatedness that is actually untrue.（读者试译） Indeed, the problem with relying on anatomical features, such as hip-shape, to classify animals is well illustrated by dinosaurs themselves. It was not bird-hipped Ornithischia that gave rise to birds, but lizard-hipped theropods.

Baron博士的分类法是否能够经受住检验尚待证实。 “期待您的翻译，将您的理解留言在文章下方留言处，第二天将会有长难句解析。” 实际上，恐龙自己就展示了依靠解剖学特征（例如骨盆形状）进行物种分类的缺点：鸟类的祖先其实并非拥有鸟臀状骨盆的鸟臀目恐龙，而是具有蜥蜴状骨盆的蜥臀目恐龙。

• Anatomy：n. 解剖；解剖学

• be vulnerable to：易受……的伤害

翻译 ▍ 陌生、c、Serena

审核 ▍妖精

编辑 ▍小小鱼