Dental Morphology and Variation in Theropod Dinosaurs

兽脚类恐龙的牙齿形态和变异华盛顿大学EAR-0545782ABSTRACT尽管对恐龙进行了200多年的持续研究，但识别特定的孤立骨骼和牙齿属于哪个物种是一个尚未得到满意解决的问题，而且这个问题是一个重要的问题，因为大多数发现的恐龙化石都是孤立的骨骼和牙齿。食肉恐龙的牙齿是中生代沉积物中发现的最常见的脊椎动物化石之一，被釉质覆盖，是脊椎动物身体中最坚硬的物质，当作为化石保存时，通常会保留大量原始解剖结构。因此，如果这些元素能够与特定物种相关联，食肉恐龙的牙齿将成为一个重要的数据集。然而，就像孤立的骨骼一样，之前在这些牙齿上所做的工作并没有产生一种严格的方法来确定它们与物种的关联。那么，这就是这个项目的目的。该项目的目标有两个。第一个是开发一种方法，通过这种方法可以将孤立的牙齿与已知物种联系起来。第二种方法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。第一个目标是通过推导出一系列描述牙齿形态的令人满意的定量测量来实现(这里之所以依赖定量测量，是因为捕食性恐龙的牙齿是相当简单的结构，几乎没有保留诊断解剖学特征，这就是它们在孤立时很难识别的原因)。第二个目标是通过使用这些测量收集位于已知物种颌骨内的牙齿的数据来实现的。因此，与该项目有关的许多工作都涉及测量已知物种的牙齿，以便纳入标准数据集，以使其尽可能完整。完成这两项任务后，应该可以对物种亲缘关系未知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，有望将该牙齿归类为数据集中的物种之一。这项工作应该有助于对古生物进行多条线索的调查。在化石组合中自信地识别更多捕食性恐龙牙齿的能力，应该会促进对动物群变化和灭绝以及种群动态和捕食者/猎物关系的研究。这里使用的方法也可以作为其他研究人员探索其他动物群体的牙齿形态的模型。最终，这些方法、数据和图像数据库将被放到网上，供所有对这一主题感兴趣的研究人员访问。这应该有助于对工作采取后续行动并加以批评。这项研究也是对公众友好的。这些牙齿很壮观，很容易运输化石；科普观众肯定会对此做出反应。如果沟通正确，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猎杀死动物的战利品；它特别适合于证明科学中假设检验的性质。

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.