Dental Morphology and Variation in Theropod Dinosaurs

兽脚亚目恐龙的牙齿形态和变异尽管对恐龙的研究已经持续了200多年，但确定特定的孤立的骨骼和牙齿属于哪个物种是一个没有得到满意解决的问题，这个问题是一个重要的问题，因为发现的大多数恐龙化石都是孤立的骨骼和牙齿。食肉恐龙牙齿是在中生代沉积物中发现的最常见的脊椎动物化石之一，由于牙齿表面覆盖着脊椎动物体内最坚硬的物质牙釉质，因此在作为化石保存时，通常会保留大量的原始解剖结构。因此，如果这些元素可以自信地与特定物种联系起来，食肉恐龙的牙齿将是一个重要的数据集。然而，与孤立的骨骼一样，先前对这些牙齿所做的工作并没有得出一个严格的方法，可以自信地将它们与物种联系起来。这就是这个项目的目的。该项目的目标是双重的。首先是发展一种方法，使孤立的牙齿与已知的物种联系起来。第二种是收集已知来自特定物种的牙齿数据集，作为比较孤立牙齿的标准。第一个目标是通过得出一系列定量测量来解决，这些测量可以令人满意地描述牙齿形态（这里依赖于定量测量，因为掠食性恐龙的牙齿是相当简单的结构，保留了很少的诊断解剖学特征，这就是它们在分离时难以识别的原因）。第二个目标是通过使用这些测量来收集已知物种颌内牙齿的数据。因此，与该项目相关的大部分工作都涉及测量已知物种的牙齿，以便将其纳入标准数据集，以使其尽可能完整。完成这两项任务后，应该可以对未知物种亲缘性的孤立牙齿进行相同的测量，并将其与标准数据集进行比较，希望能将该牙齿分类为数据集中的物种之一。这项工作将促进许多方面的古生物学研究。在化石组合中自信地识别更多掠食性恐龙牙齿的能力，将改善对动物变化和灭绝以及种群动态和捕食者/猎物关系的研究。这里使用的方法可能为其他研究人员探索其他动物群体的牙齿形态提供一个模型。最终，方法、数据和图像数据库将被放到网上，供所有对该主题感兴趣的研究人员访问。这将有助于对工作进行跟踪和批评。这项研究对公众也很友好。这些牙齿非常壮观，很容易运输化石；这是科普观众肯定会有反应的。如果沟通得当，这个项目可能是一个很好的方式，表明古生物学可以不仅仅是狩猎死去的动物；它特别适合于演示科学中假设检验的本质。

DENTAL MORPHOLOGY AND VARIATION IN THEROPOD DINOSAURSJoshua SmithWashington UniversityEAR-0545782ABSTRACTDespite more than 200 years of continual research on dinosaurs, identifying to which species particular isolated bones and teeth belong is a problem that has not been resolved to satisfaction, and the issue is an important one as most of the dinosaur fossils discovered are isolated bones and teeth. Predatory dinosaur teeth are among the most common vertebrate fossils found in sediments of Mesozoic age and, being covered with enamel, the hardest substance in the vertebrate body, usually preserve a large amount of their original anatomy when preserved as fossils. As such, predatory dinosaur teeth would be an important dataset if these elements could be confidently correlated with particular species. As with isolated bones, however, the previous work that has been done on these teeth has not resulted in a rigorous means by which to confidently correlate them with species. That then, is the purpose of this project. The project's aims are twofold. The first is to develop a means by which it is possible to correlate an isolated tooth with a known species. The second is to amass a dataset of teeth known to come from particular species to serve as a standard against which to compare isolated teeth. The first goal is being addressed by deriving a series of quantitative measurements that do a satisfactory job of describing tooth morphology (quantitative measurements are relied on here because predatory dinosaur teeth are fairly simple structures that preserve few diagnostic anatomical features, which is the reason that they are so difficult to identify when isolated). The second goal is being addressed by using these measurements to collect data from teeth located within the jaws of known species. Much of the work related to this project is thus involved in measuring teeth of known species for inclusion into the standard dataset, to make it as complete as possible. With these two tasks accomplished it should then be possible to make the same measurements on an isolated tooth of unknown species affinity and compare it to the standard dataset, hopefully resulting in a classification of that tooth as one of the species in the dataset. This work should facilitate many lines of paleontological inquiry. The ability to confidently identify more predatory dinosaur teeth in a fossil assemblage should improve research on faunal change and extinctions as well as on population dynamics and predator/prey relationships. The methods used here might serve as a model for other researchers to explore dental morphology in other groups of animals as well. Ultimately, the methods, data, and image database will be put online for access by all researchers interested in the subject. This should facilitate the work being followed up and critiqued. The research is also public friendly. These teeth are spectacular and easy to transport fossils; something a popular science audience is sure to respond to. If communicated correctly, this project might be a good way to show that paleontology can be more than trophy hunting dead animals; it is especially well suited to demonstrating the nature of hypothesis testing in science.