FINITE ELEMENT, OCCLUSAL, MICROWEAR AND MICROSTRUCTURAL ANALYSES INDICATE THAT CONODONT MICROSTRUCTURE IS ADAPTED TO DENTAL FUNCTION
FINITE ELEMENT, OCCLUSAL, MICROWEAR AND MICROSTRUCTURAL ANALYSES INDICATE THAT CONODONT MICROSTRUCTURE IS ADAPTED TO DENTAL FUNCTION
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DOI：
10.1111/pala.12102
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发表时间：
2014-09-01
期刊：
影响因子：
2.6
通讯作者：
Donoghue, Philip C. J.
中科院分区：
文献类型：
--
作者：
Martinez-Perez, Carlos;Rayfield, Emily J.;Donoghue, Philip C. J.
牙形刺构成了脊椎动物进化谱系中骨骼生物矿化的最早证据，表现为由牙釉质和牙本质样组织组成的齿状元素的摄食装置，这些组织与其他全群颌口动物中的这些典型组织平行进化。因此，这个进化平行性的非凡例子提供了一个自然的实验，可以探索脊椎动物骨骼进化的限制。利用有限元分析，根据咬合和微磨损分析，我们测试了这样的假设：牙形牙和其他脊椎动物的牙釉质样组织中复杂的牙齿功能和微观结构分化的一致性是功能适应的结果。我们的结果显示了应力分布和微晶取向模式的拓扑共变。在高应力区域，例如基底腔的顶点和平台的内部部分，牙冠组织包括交织的棱柱，棱柱之间的不连续性会起到交叉裂纹的作用，从而防止裂纹扩展。这些结果为平台牙形刺元件的一般咬合模型提供了信息，并证明牙形刺冠组织的复杂微观结构是对元件所执行的牙齿功能的适应。
Conodonts constitute the earliest evidence of skeletal biomineralization in the vertebrate evolutionary lineage, manifest as a feeding apparatus of tooth-like elements comprised of enamel- and dentine-like tissues that evolved in parallel with these canonical tissues in other total-group gnathostomes. As such, this remarkable example of evolutionary parallelism affords a natural experiment in which to explore the constraints on vertebrate skeletal evolution. Using finite element analysis, informed by occlusal and microwear analyses, we tested the hypothesis that coincidence of complex dental function and microstructural differentiation in the enamel-like tissues of conodonts and other vertebrates is a consequence of functional adaptation. Our results show topological co-variation in the patterns of stress distribution and crystallite orientation. In regions of high stress, such as the apex of the basal cavity and inner parts of the platform, the crown tissue comprises interwoven prisms, discontinuities between which would have acted to decussate cracks, preventing propagation. These results inform a general occlusal model for platform conodont elements and demonstrate that the complex microstructure of conodont crown tissue is an adaptation to the dental functions that the elements performed.