RUI - Phylogenetic Analysis of the Cetacean Basal Cranium and Inner Ear and Study of the Cetacean Relationships

小行星9419898 鲸目动物（鲸鱼、鼠海豚和海豚）的系统发育关系为理解其巨大的多样性和独特的水生适应性提供了基础。最近的分子和古生物学研究的鲸类动物提出了非常不同的假设，鲸类动物的关系，将导致不同的进化解释，其水生专业化。为了验证这些相互竞争的假设，拟议的研究将检查颅骨和耳朵的形态特征。虽然基颅在其他哺乳动物的研究中是一个非常有用的系统特征来源，但它在鲸类中的研究相对不足。因此，一个彻底的系统发育分析的basicranium有很好的潜力，产生新的数据推断鲸类的关系。 现代鲸类中的两大类，齿鲸（齿鲸）和须鲸（须鲸），在水下有着非常不同的听觉机制。现代齿鲸有一些内耳结构专门用于听到高频声音，这对它们的回声定位（声纳）至关重要。相比之下，现存的须鲸完全依赖低频声音。与现代齿鲸类和神秘鲸类之间的这些功能差异有关的解剖学数据非常有限。对鲸类化石的耳朵结构知之甚少。因此，关于鲸类耳朵结构进化的几个问题尚未得到解决。本研究将使用连续研磨、工业CT扫描和计算机图形重建等精确技术，检查化石和现存齿鲸类、神秘鲸类和灭绝的古鲸类的内耳。使用这些技术进行详细的研究将为鲸类动物进化生物学提供新的数据，并检验关于鲸类动物耳结构进化的假设。

9419898 Luo The phylogenetic relationships of cetaceans (whales, porpoises and dolphins) provide the basis for understanding their great diversity and unique aquatic adaptations. Recent molecular and paleontological studies of cetaceans have posed very different hypotheses for cetacean relationships that would lead to different evolutionary interpretations of their aquatic specializations. To test these competing hypotheses, the proposed research will examine the morphological characteristics of the cranium and the ear. Although the basicranium is a very useful source of systematic characters in studies of other mammals, it has been relatively under-explored in cetaceans. Therefore, a thorough phylogenetic analysis of the basicranium has a good potential to generate new data for inferring relationships of cetaceans. Two groups of modern cetaceans, the odontocetes (toothed whales) and the mysticetes (baleen whales), have very different underwater hearing mechanisms. Modern toothed whales have some inner ear structures specialized for hearing high frequency sound that is crucial for their echolocation (sonar). By contrast, extant baleen whales rely entirely on the low frequency sounds. The anatomical data that are related to these functional differences between modern odontocetes and mysticetes are very limited. Little is known of the ear structures of fossil cetaceans. As a result, several issues on the structural evolution of cetacean ears have not been resolved. This study will examine the inner ears of fossil and extant odontocetes, mysticetes and the extinct archaeocetes, using accurate techniques of serial grinding, the industrial CT scanning, and computer graphic reconstruction. A detailed study using these techniques will contribute new data to cetacean evolutionary biology, and test hypotheses on the structural evolution of the cetacean ear.