Snively Eric, O'Brien Haley, Henderson Donald M, Mallison Heinrich, Surring Lara A, Burns Michael E, Holtz Thomas R, Russell Anthony P, Witmer Lawrence M, Currie Philip J, Hartman Scott A, Cotton John R
Department of Biology, University of Wisconsin-La Crosse, La Crosse, WI, USA.
Department of Anatomy and Cell Biology, Oklahoma State University Center for Health Sciences, Tulsa, OK, USA.
PeerJ. 2019 Feb 21;7:e6432. doi: 10.7717/peerj.6432. eCollection 2019.
Tyrannosaurid dinosaurs had large preserved leg muscle attachments and low rotational inertia relative to their body mass, indicating that they could turn more quickly than other large theropods.
To compare turning capability in theropods, we regressed agility estimates against body mass, incorporating superellipse-based modeled mass, centers of mass, and rotational inertia (mass moment of inertia). Muscle force relative to body mass is a direct correlate of agility in humans, and torque gives potential angular acceleration. Agility scores therefore include rotational inertia values divided by proxies for (1) muscle force (ilium area and estimates of m. caudofemoralis longus cross-section), and (2) musculoskeletal torque. Phylogenetic ANCOVA (phylANCOVA) allow assessment of differences in agility between tyrannosaurids and non-tyrannosaurid theropods (accounting for both ontogeny and phylogeny). We applied conditional error probabilities () to stringently test the null hypothesis of equal agility.
Tyrannosaurids consistently have agility index magnitudes twice those of allosauroids and some other theropods of equivalent mass, turning the body with both legs planted or pivoting over a stance leg. PhylANCOVA demonstrates definitively greater agilities in tyrannosaurids, and phylogeny explains nearly all covariance. Mass property results are consistent with those of other studies based on skeletal mounts, and between different figure-based methods (our main mathematical slicing procedures, lofted 3D computer models, and simplified graphical double integration).
The capacity for relatively rapid turns in tyrannosaurids is ecologically intriguing in light of their monopolization of large (>400 kg), toothed dinosaurian predator niches in their habitats.
霸王龙类恐龙相对于其体重具有较大的保存下来的腿部肌肉附着点和较低的转动惯量，这表明它们比其他大型兽脚亚目恐龙能够更快地转身。
为了比较兽脚亚目恐龙的转身能力，我们将敏捷性估计值与体重进行回归分析，纳入基于超椭圆模型的质量、质心和转动惯量（质量惯性矩）。相对于体重的肌肉力量是人类敏捷性的直接相关因素，而扭矩产生潜在的角加速度。因此，敏捷性得分包括转动惯量值除以以下两者的代理值：（1）肌肉力量（髂骨面积和长尾股肌横截面估计值），以及（2）肌肉骨骼扭矩。系统发育协方差分析（phylANCOVA）允许评估霸王龙类和非霸王龙类兽脚亚目恐龙之间的敏捷性差异（同时考虑个体发育和系统发育）。我们应用条件错误概率（）来严格检验敏捷性相等的零假设。
霸王龙类的敏捷性指数大小始终是异特龙类和其他一些同等体重的兽脚亚目恐龙的两倍，它们可以双腿站立转身或围绕一条支撑腿旋转身体。系统发育协方差分析明确表明霸王龙类具有更高的敏捷性，并且系统发育解释了几乎所有的协方差。质量属性结果与其他基于骨骼模型的研究结果一致，并与不同的基于图形的方法（我们主要的数学切片程序、放样三维计算机模型和简化的图形双重积分）一致。
鉴于霸王龙类在其栖息地垄断了大型（>400千克）有齿恐龙捕食者生态位，它们相对快速转身的能力在生态学上很有趣。
