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

9419898罗鲸目动物(鲸鱼、江豚和海豚)的系统发育关系为了解它们的巨大多样性和独特的水生适应能力提供了基础。最近对鲸目动物的分子和古生物学研究对鲸目动物的关系提出了非常不同的假说，这将导致对其水生专门化的不同进化解释。为了检验这些相互竞争的假说，这项拟议的研究将检查头骨和耳朵的形态特征。尽管在其他哺乳动物的研究中，基骨是一个非常有用的系统特征来源，但在鲸目动物中，它的开发相对较少。因此，对基本脊椎动物的系统发育分析具有很好的潜力，可以产生新的数据来推断鲸类的亲缘关系。现代鲸目动物中的两类，齿鲸(齿鲸)和神秘鲸(须鲸)，在水下的听力机制非常不同。现代齿鲸有一些专门用来听高频声音的内耳结构，这对它们的回声定位(声纳)至关重要。相比之下，现存的须鲸完全依靠低频声音。与现代齿齿动物和神秘动物之间的这些功能差异有关的解剖学数据非常有限。鲸目动物化石的耳朵结构知之甚少。因此，关于鲸目动物耳朵结构进化的几个问题尚未得到解决。本研究将利用连续研磨、工业CT扫描和计算机图形重建的精确技术，对化石和现存的齿形类、神秘类和已灭绝的古生物的内耳进行研究。使用这些技术的详细研究将为鲸目动物进化生物学提供新的数据，并检验关于鲸目动物耳朵结构进化的假说。

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.