近日，美国自然历史博物馆Mark A. Norell及其课题组的论文发现了兽脚亚目恐龙腕部的重组早于鸟类飞行的起源。这一研究成果发表在2025年7月9日出版的国际学术期刊《自然》上。

课题组描述了来自蒙古戈壁沙漠的两个新制备的兽脚亚目恐龙标本的前肢骨骼，每个标本都保留了一个梨形，除了鸟类之外，它还存在于窃蛋龙和短齿龙科中。根据这些标本对已发表的材料进行的重新解释表明，在包括小盗龙、翼龙和近鸟龙在内的许多兽脚亚目物种中都有一种鱼状化石。他们的研究结果表明，钩状骨取代尺状骨成为了Pennaraptora进化枝的起源，在系统发育上与鸟类及其近亲飞行的假设起源一致。综上所述，他们的研究结果表明，钩状骨取代尺骨是恐龙飞行装置组装的最后一步——这一过程与兽脚亚目恐龙的飞行起源很接近，而不是鸟类独有的新奇现象。

据了解，鸟类的腕骨（腕）有着复杂的进化史，长期以来人们都知道腕骨的退化，最近又发现腕骨（尺骨）被另一腕骨（鱼状骨）取代。在飞行过程中，鱼状体在稳定远端翼尖方面起着至关重要的作用，并促进了“自动”机翼运动的运动学整合。除了最早的兽脚亚目恐龙外，其他所有恐龙身上都明显没有梨状骨，这使得人们提出，在兽脚亚目恐龙进化的早期，梨状骨就消失了，只有在鸟类身上才重新出现，这是飞行起源的关键一步。

附：英文原文

Title: Reorganization of the theropod wrist preceded the origin of avian flight

Author: Napoli, James G., Fabbri, Matteo, Ruebenstahl, Alexander A., OConnor, Jingmai K., Bhullar, Bhart-Anjan S., Norell, Mark A.

Issue&Volume: 2025-07-09

Abstract: The carpus (wrist) of birds has a complex evolutionary history, long known to involve carpal reduction and recently shown to include topological replacement of one carpal (the ulnare) by another (the pisiform)1. The pisiform plays a crucial role in stabilization of the distal wingtip during flight2, and facilitates kinematic integration that ‘automates’ wing motion3. The apparent absence of a pisiform in all but the earliest theropod dinosaurs led to the proposal that it was lost early in theropod evolution and regained only in birds as a key step in the origin of flight1. Here, we describe the forelimb skeletons of two newly prepared theropod dinosaur specimens from the Gobi Desert of Mongolia, each of which preserves a pisiform, establishing its presence in Oviraptorosauria and Troodontidae in addition to birds. Reinterpretation of published material in light of these specimens shows a pisiform in a wide range of theropod species, including Microraptor4, Ambopteryx5 and Anchiornis6. Our results indicate that the pisiform replaced the ulnare by origin of the clade Pennaraptora, phylogenetically coincident with the hypothesized origin(s) of flight in birds and their closest relatives7,8. Taken together, our results indicate that replacement of the ulnare by the pisiform was a terminal step in assembly of the dinosaurian flight apparatus that occurred close to the origins of flight in theropod dinosaurs, rather than a novelty restricted to birds.

DOI: 10.1038/s41586-025-09232-3

Source: https://www.nature.com/articles/s41586-025-09232-3