Not your father's homodonty-stress, tooth shape, and the functional homodont
Not your father's homodonty-stress, tooth shape, and the functional homodont
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DOI：
10.1111/joa.13248
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发表时间：
2020-07-19
影响因子：
2.4
通讯作者：
Summers, Adam P.
中科院分区：
文献类型：
--
作者：
Cohen, Karly E.;Weller, Hannah, I;Summers, Adam P.
牙齿讲述了捕食者和猎物之间相互作用的故事。如果一组牙齿由看起来相似的牙齿组成，它们在形态上是同齿的，但如果在大小或形状上有未指明的区域专门化，它们在形态上是异齿的。这些都是模糊的术语，没有有用的功能含义，因为形态同齿并不一定等于功能同牙。看起来一样的牙齿可能功能不同。锥形牙齿在鱼类中很常见，表面上的任务是简单地刺穿。圆锥形牙齿的形状和位置有很大的变化。前牙可能比后牙大，较大的牙齿可能被较小的牙齿包围，斑块的牙齿可能都具有相同的大小和形状。这些变化表明，锥形牙列可能代表着不同功能问题的单一形态解决方案。我们对同齿的概念很感兴趣，并使用圆锥齿作为区分牙齿形状和性能的模型。我们认为牙齿对猎物施加的压力是造成损害的原因。为了建立功能同牙的统计测量，通过测量表面积、位置和施加的力来计算应力。功能性同牙则被定义为牙齿沿颌部承受/施加相似应力的程度，尽管形状发生了变化。我们发现，形态上的异齿牙齿在功能上通常是同齿的，而且这一位置比形状更能预测性能。此外，牙齿的排列会影响它们的功能，因此，在一颗单独的大牙齿周围有几颗较小的牙齿具有功能上的优势。我们证明，这种牙齿的排列对在穿孔时抓取猎物是有用的，而不是撕裂，较小的牙齿分散了较大牙齿周围的巨大应力。我们表明，测量形状如何影响应力分布对载荷的响应使我们对锥形牙齿的演化有了更清晰的了解。
Teeth tell the tale of interactions between predator and prey. If a dental battery is made up of teeth that look similar, they are morphologically homodont, but if there is an unspecified amount of regional specialization in size or shape, they are morphologically heterodont. These are vague terms with no useful functional implication because morphological homodonty does not necessarily equal functional homodonty. Teeth that look the same may not function the same. Conical teeth are prevalent in fishes, superficially tasked with the simple job of puncture. There is a great deal of variation in the shape and placement of conical teeth. Anterior teeth may be larger than posterior ones, larger teeth may be surrounded by small ones, and patches of teeth may all have the same size and shape. Such variations suggest that conical dentitions might represent a single morphological solution for different functional problems. We are interested in the concept of homodonty and using the conical tooth as a model to differentiate between tooth shape and performance. We consider the stress that a tooth can exert on prey as stress is what causes damage. To create a statistical measure of functional homodonty, stress was calculated from measurements of surface area, position, and applied force. Functional homodonty is then defined as the degree to which teeth along the jaw all bear/exert similar stresses despite changes in shape. We find that morphologically heterodont teeth are often functionally homodont and that position is a better predictor of performance than shape. Furthermore, the arrangement of teeth affects their function, such that there is a functional advantage to having several smaller teeth surrounding a singular large tooth. We demonstrate that this arrangement of teeth is useful to grab, rather than tear, prey upon puncture, with the smaller teeth dissipating large stress forces around the larger tooth. We show that measurements of how shape affects stress distribution in response to loading give us a clearer picture of the evolution of conically shaped teeth.