Inferring lifestyle for Aves and Theropoda: a model based on curvatures of extant avian ungual bones
Inferring lifestyle for Aves and Theropoda: a model based on curvatures of extant avian ungual bones
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推断鸟类和兽脚类的生活方式：基于现存鸟类爪骨曲率的模型
DOI：
10.1101/517375
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Cobb S
中科院分区：
文献类型：
--
作者：
Cobb S
爪子参与许多行为，包括运动和捕获猎物，因此动物进化出了实现这些功能的爪子形态。过去的作者发现爪角蛋白鞘的几何形状与现存鸟类和有鳞动物的生活方式相关。这种关系经常被用来推断包括始祖鸟在内的中生代兽脚类动物的生活方式。然而，许多爪子化石缺乏角质鞘，因此无法使用现有方法进行分析。由于爪内的趾骨在化石记录中更常见，因此该骨头的几何形状可能为古生物学分析提供更有用的指标。在这项研究中，使用 X 射线技术对 108 只鸟类和 5 个鳞状动物的爪骨进行了成像，并发现了足趾 III 爪内的爪骨曲率与四种生活方式之间的关系；地面栖息、栖息、掠食性和掠食性；使用加权精度等于 0.79 的线性判别分析。我们的模型预测了始祖鸟和小盗龙的树栖生活方式以及孔子鸟的掠食性生态。这些发现证明了我们的模型在回答古生态学、兽脚亚目鸟类过渡和鸟类飞行进化等问题方面的实用性。尽管该指标与生活方式具有很强的相关性，但 PD-III 曲率的形态空间重叠，因此该指标应与其他证据一起考虑。
Claws are involved in a number of behaviours including locomotion and prey capture, and as a result animals evolve claw morphologies that enable these functions. Past authors have found geometry of the keratinous sheath of the claw to correlate with mode of life for extant birds and squamates; this relationship has frequently been cited to infer lifestyles for Mesozoic theropods includingArchaeopteryx. However, many fossil claws lack keratinous sheaths and thus cannot be analysed using current methods. As the ungual phalanx within the claw is more commonly preserved in the fossil record, geometry of this bone may provide a more useful metric for paleontological analysis. In this study, ungual bones of 108 birds and 5 squamates were imaged using X-ray techniques and a relationship was found between curvatures of the ungual bone within the claw of pedal digit III and four modes of life; ground-dwelling, perching, predatory, and scansorial; using linear discriminant analysis with weighted accuracy equal to 0.79. Our model predicts arboreal lifestyles forArchaeopteryxandMicroraptorand a predatory ecology forConfuciusornis. These findings demonstrate the utility of our model in answering questions of palaeoecology, the theropod-bird transition, and the evolution of avian flight. Though the metric exhibits a strong correlation with lifestyle, morphospaces for PD-III curvatures overlap and so this metric should be considered alongside additional evidence.