An investigation of tetrapod skull architecture using advanced computer modelling techniques

动物的头骨必须在强度和稳定性与灵活性的矛盾要求之间取得平衡，这样它们才能把嘴张得尽可能大，在不损害封闭的大脑和感觉器官的情况下施加最大的咬合力。爬行动物、鸟类和哺乳动物的祖先除了眼睛和耳朵开口外，还有一个坚实的头骨，但他们很快就开始在眼睛后面的头骨一侧发育开口（窗洞）；现在不同的头骨有不同的开窗模式，但仍然不知道为什么。此外，头骨的整体几何形状也不同。在颅骨深度、大脑和/或感觉器官的大小、颌骨肌肉的复杂程度以及颈部的长度等方面都存在差异。所有这些特征，单独或联合起来，对颅骨功能（生物力学）有重大影响，并可能是活体动物颅骨结构根本差异的基础。本研究的目的是了解活体动物的生物力学力与颅骨形状之间的关系，特别是确定颅骨开窗的生物力学意义。为了完成这项工作，我们需要结合机械工程师、数字成像仪、骨生物学家和形态学家的专业知识，并使用先进的计算机建模技术来执行复杂的生物力学分析。在这个项目中，来自博物馆活体动物标本的信息（通过先进的计算机成像-高分辨率计算机x射线断层扫描获得）将被结合起来，以建立一系列头骨的精确模型。这些可以修改以改变基本参数（例如眼睛大小，大脑大小，开窗模式），然后以模拟颌骨和颈部肌肉变化的复杂性，大脑和感觉器官大小的变化和/或增加咬合力的方式加载。因此，我们第一次可以测试一系列理论来解释头骨的形状。这项研究不仅将推进我们对一组关键生物的发展的认识，而且还将加深我们对生物力学力、软组织结构和骨骼形状之间复杂关系的理解。理解这种复杂的关系是很重要的，不仅对一般生物学，而且对医学（如骨修复和重塑，过度使用损伤，骨质疏松症）。

The skulls of animals must balance the conflicting demands of strength and stability with flexibility, so that they can open their mouths as wide as possible and apply a maximum bite force without damaging the enclosed brain and sense organs. Ancestors of reptiles, birds and mammals had a solid skull except for eye and ear openings, but they soon began to develop openings (fenestrae) in the side of the skull behind the eyes; now different skulls have different patterns of fenestrae, but it is still not understood why. Furthermore the overall geometries of skulls are different. There is variation in skull depth, in the size of the brain and/or sense organs, in the complexity of the jaw muscles, and in the length of the neck. All of these features, individually or in combination, have a major effect on skull function (biomechanics) and may underlie the radical differences in skull architecture of living animals. The aim of this research is to understand the relationship between biomechanical forces and skull shape in living animals, and in particular to determine the biomechanical significance of skull fenestrations. To do this work, we need to combine the expertise of mechanical engineers, digital imagers, bone biologists, and morphologists, and use advanced computer modelling techniques to perform sophisticated biomechanical analyses. In this project, information from museum specimens of living animal groups (obtained by advanced computer imaging - High Resolution Computed X-ray Tomography) will be combined to develop accurate models of a range of skulls. These can be modified to change basic parameters (e.g. eye size, brain size, patterns of fenestration), and then loaded in ways that simulate changing complexities of the jaw and neck muscles, changes in size of the brain and sense organs, and/or increasing bite force. As a result, we can, for the first time, test a series of theories to explain skull shape. Not only will the study advance our knowledge of the development of a key group of organisms but it will also deepen our understanding of the complex relationship between biomechanical forces, soft tissue structures and skeletal shape. Understanding this complex relationship is important, not only to general biology but also to medicine (e.g. bone repair and remodelling, over-use injuries, osteoporosis).