美国俄亥俄州大学传统骨科医学院Patrick M. O’Connor研究组取得一项新突破。他们通过研究马达加斯加的晚白垩纪鸟类揭示了喙的独特发育。该研究于2020年11月25日发表于《自然》。

他们描述了一只乌鸦大小的干鸟-Falcatakely forsterae gen. et sp. nov.。来自马达加斯加的晚白垩纪时代，它具有长而深的吻突，这种喙状形态以前在中生代鸟类中没有出现过，并且其表面类似于各种冠群鸟类（例如巨嘴鸟）。Falcatakely的吻突由一个扩张的无牙上颌和一个小的带齿前颌组成。对单个骨元素和三维吻突形状的形态计量学分析显示，尽管类似于nonavialan节肢动物，保留了上颌-前颌组织，但其具有像神经鸟氨酸样的面部发育。Falcatakely中吻突的形状和高度增加揭示了发育不稳定性的程度和形态差异的增加，这在早期分支的鸟中是没出现过的。这种表型（和推测的生态学）在干鸟中的表达强调了巩固至神经氨酸样、上颌前占主导的吻突不是喙增大的进化先决条件。

据了解，中生代鸟类在大小、飞行适应性和羽毛组织上表现出相当大的多样性，但表现出相对保守的喙形和发育模式。尽管Neornithine（也就是冠状群）鸟类也表现出对面部发育的限制，但与中生代鸟类相比，它们具有相对多样的喙形态，与一系列的摄食和行为生态有关。

附：英文原文

Title: Late Cretaceous bird from Madagascar reveals unique development of beaks

Author: Patrick M. OConnor, Alan H. Turner, Joseph R. Groenke, Ryan N. Felice, Raymond R. Rogers, David W. Krause, Lydia J. Rahantarisoa

Issue&Volume: 2020-11-25

Abstract: Mesozoic birds display considerable diversity in size, flight adaptations and feather organization1,2,3,4, but exhibit relatively conserved patterns of beak shape and development5,6,7. Although Neornithine (that is, crown group) birds also exhibit constraint on facial development8,9, they have comparatively diverse beak morphologies associated with a range of feeding and behavioural ecologies, in contrast to Mesozoic birds. Here we describe a crow-sized stem bird, Falcatakely forsterae gen. et sp. nov., from the Late Cretaceous epoch of Madagascar that possesses a long and deep rostrum, an expression of beak morphology that was previously unknown among Mesozoic birds and is superficially similar to that of a variety of crown-group birds (for example, toucans). The rostrum of Falcatakely is composed of an expansive edentulous maxilla and a small tooth-bearing premaxilla. Morphometric analyses of individual bony elements and three-dimensional rostrum shape reveal the development of a neornithine-like facial anatomy despite the retention of a maxilla–premaxilla organization that is similar to that of nonavialan theropods. The patterning and increased height of the rostrum in Falcatakely reveals a degree of developmental lability and increased morphological disparity that was previously unknown in early branching avialans. Expression of this phenotype (and presumed ecology) in a stem bird underscores that consolidation to the neornithine-like, premaxilla-dominated rostrum was not an evolutionary prerequisite for beak enlargement.

DOI: 10.1038/s41586-020-2945-x

Source: https://www.nature.com/articles/s41586-020-2945-x