Throughout their 250 Myr history, archosaurian reptiles have exhibited a wide array of body sizes, shapes, and locomotor habits, especially in regard to terrestriality. These features make Archosauria a useful clade with which to study the interplay between body size, shape, and locomotor behavior, and how this interplay may have influenced locomotor evolution. Here, digital volumetric models of 80 taxa are used to explore how mass properties and body proportions relate to each other and locomotor posture in archosaurs. One-way, nonparametric, multivariate analysis of variance, based on the results of principal components analysis, shows that bipedal and quadrupedal archosaurs are largely distinguished from each other on the basis of just four anatomical parameters (p < 0.001): mass, center of mass position, and relative forelimb and hindlimb lengths. This facilitates the development of a quantitative predictive framework that can help assess gross locomotor posture in understudied or controversial taxa, such as the crocodile-line Batrachotomus (predicted quadruped) and Postosuchus (predicted biped). Compared with quadrupedal archosaurs, bipedal species tend to have relatively longer hindlimbs and a more caudally positioned whole-body center of mass, and collectively exhibit greater variance in forelimb lengths. These patterns are interpreted to reflect differing biomechanical constraints acting on the archosaurian Bauplan in bipedal versus quadrupedal groups, which may have shaped the evolutionary histories of their respective members.

中文翻译：

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陆生主龙的质量特性和身体比例与运动习惯的关系

在它们 250 密尔的历史中，主龙爬行动物表现出各种各样的体型、形状和运动习惯，尤其是在陆地方面。这些特征使 Archosauria 成为研究体型、形状和运动行为之间相互作用的有用分支，以及这种相互作用如何影响运动进化。在这里，使用 80 个分类单元的数字体积模型来探索质量属性和身体比例如何相互关联，以及主龙的运动姿势。基于主成分分析结果的单向、非参数、多变量方差分析表明，仅基于四个解剖参数，双足和四足主龙在很大程度上就可以相互区分。p< 0.001)：质量、质心位置和相对前肢和后肢长度。这促进了定量预测框架的开发，该框架可以帮助评估未充分研究或有争议的分类群（例如鳄鱼线）中的总体运动姿势鲶鱼（预计四足）和后鳄（预测的两足动物）。与四足主龙类相比，双足类物种往往具有相对较长的后肢和更位于尾部的全身质心，并且总体上表现出更大的前肢长度差异。这些模式被解释为反映作用于主龙类的不同生物力学约束保普兰在双足与四足群体中，这可能塑造了各自成员的进化历史。