Abstract：
The vast majority of pterosaurs are characterized by relatively large, elongate heads that are often adorned with large, elaborate crests. Projecting out in front of the body, these large heads and any crests must have had an aerodynamic effect. The working hypothesis of the present study is that these oversized heads were used to control the left-right motions of the body during flight. Using digital models of eight non-pterodactyloids (\"rhamphorhyncoids\") and ten pterodactyloids, the turning moments associated with the head + neck show a close and consistent correspondence with the rotational inertia of the whole body about a vertical axis in both groups, supporting the idea of a functional relationship. Turning moments come from calculating the lateral area of the head (plus any crests) and determining the associated lift (aerodynamic force) as a function of flight speed, with flight speeds being based on body mass. Rotational inertias were calculated from the three-dimensional mass distribution of the axial body, the limbs, and the flight membranes. The close correlation between turning moment and rotational inertia was used to revise the life restorations of two pterosaurs and to infer relatively lower flight speeds in another two.
摘要：
绝大多数翼龙的特点是相对较大，细长的头部，通常装饰着大的，精致的波峰。投射在身体前面，这些大头和任何波峰一定有空气动力学效应。本研究的工作假设是，这些超大的头部用于控制飞行过程中身体的左右运动。使用八种非翼术（“rhamphorhyncoids”）和十种翼术的数字模型，与头颈部相关的转动力矩显示出与两组中整个身体围绕垂直轴的旋转惯性紧密一致的对应关系，支持功能关系的想法。转弯力矩来自计算头部的横向面积（加上任何波峰）并确定相关的升力（气动力）作为飞行速度的函数，飞行速度取决于体重。根据轴体的三维质量分布计算旋转惯性，四肢,和飞行膜。转弯力矩和旋转惯性之间的紧密相关性被用来修改两个翼龙的寿命恢复，并推断另外两个翼龙的飞行速度相对较低。
