Pattern and process of serrations and denticles of reptilian teeth

锯齿的大小和形状经常被用作兽脚类恐龙的诊断特征。关于这些性状的种内变异的研究很少。这在很大程度上是因为没有一种适当的方法来描述变化并对其进行统计检验。本研究旨在建立种内变异的数字图像数据库，并探索一种合适的形态计量学方法。对两种现存爬行动物和一种已灭绝的爬行动物伶盗龙进行了牙冠基长、牙宽、牙高和齿基长的测量。Varanus之所以被选中，是因为它被认为是兽脚类恐龙最好的类似物之一。测量了鬣蜥的牙齿，并将其与斑蜥的锯齿进行了比较。伶盗龙是一种节肢恐龙，之所以被测量是因为它在锯齿中有一个衍生特征。在所有三个物种的四项测量中，锯齿/牙齿的变异最大。使用中的功能牙与相同牙位的替换牙在锯齿/齿根长度上存在差异。伶盗龙的标本没有表现出派生的字符状态。这些发现强烈表明，人们应该谨慎使用锯齿和/或牙齿上的字符。尝试了几种形态计量学分析来描述牙齿特征的变化。由于观察到锯齿/牙齿的高度变化，形态计量学方法被证明不适合描述。

Size and shape of the serrations are often used as a diagnostic character in the theropod dinosaurs. There are very few studies of intraspecific variations of these characters. It is largely because there is not an appropriate method to describe the variations and to test them statistically. This study was to create digital image database for intraspecific variations and it was also to explore a suitable morphometric method. Two species of extant reptiles, Varanus and Iguana, and one species of an extinct reptile, Velociraptor, were chosen to measure tooth crown basal length, width, height, and serration or denticle basal length. Varanus was chosen because it is considered as one of the best analogues for theropod dinosaurs. Iguana was measured to made a comparison of its denticles to the serrations of Varanus. Velociraptor, a thropod dinosaur, was measured because it has a derived character in the serrations. Variations of serrations/denticles were the greatest among the four measurements taken in all the three species. A functional tooth in use shows differences in serration/denticle basal length from a replacement tooth in the same tooth position. The Velociraptor specimen did not show a derived character state. These findings strongly suggest that one should exercise caution on the use of characters on serrations and/or denticles. Several morphometric analyses were attempted to describe variations in dental characters. Due to high variations observed in serrations/denticles, morphometric methods turned out to be not suitable for the description.