辽西热河群的恐爪龙类化石及虚骨龙类的演化

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	辽西热河群的恐爪龙类化石及虚骨龙类的演化
其他题名	DEINONYCHOSAURIAN FOSSILS FROM THE JEHOL GROUP OF WESTERN LIAONING AND THE COELUROSAURIAN EVOLUTION
	徐星
学位类型	博士
导师	李锦玲
	2002
学位授予单位	中国科学院古脊椎动物与古人类研究所
学位授予地点	中国科学院古脊椎动物与古人类研究所
学位专业	古生物学与地层学
关键词	辽西热河群恐爪龙类虚骨龙演化分支系统学
摘要	该文详细描述了中国辽西热河群10件恐爪龙类化石标本的骨骼与皮肤衍生物形态.该文对虚骨龙类的系统演化关系进行了分支系统学分析.该文首次定量检验了某些分类单元对于恢复虚骨龙美演化的重要性,首次检验了虚骨龙类身体不同部位的信息对恢复虚骨龙类系统演化研究的影响,首次定量评价了虚骨龙类演化各个阶段身体不同部位的相对变异程度.该研究表明手盗龙类主要由两大支系,即由阿佛瑞兹龙类、镰刀龙类和窃蛋龙类组成的支系和由伤齿龙类、奔龙类和鸟类组成的支系.这一结果与目前虚骨龙类的化石记录更为吻合,它表明虚骨龙类主要类群的起源时间比过去认为的要晚.该研究也支持恐爪龙类是由伤齿龙类和奔龙类组成的单系类群,但这一结论的支持强度较弱.基于得到的分支图,对虚骨龙类的演化进行了讨论:定量的研究表明虚骨龙类、手盗龙类和副鸟类这三个节点的相对形态变异程度要高于其他节点;对特征分布的分析表明向鸟类演化的主要结构性转化在手盗龙类的早期演化阶段就已完成;在某些非鸟手盗龙类中观察到一些树栖的特征.该文提出一种新的推论非鸟手盗龙类和鸟类的树栖特性的方法.定量的研究表明虚骨龙类当中存在向树栖习性演化的趋向,原始的副鸟类可能具备树栖能力,一些进步的副鸟类进一步提高了这一能力.这一古生态转化与来自独立的系统发育学分析和软体组织的信息是一致的.
其他摘要	The osteology and integument of deinonychosaurs from the Jehol Group of western Liaoning Province (China) are described in detail. Sinornithosaurus millenii, Microraptor zhanianus, and Graciliraptor lujiatunensis from Liaoning represent early diversifications of the dromaeosaurid lineage. In general, they are small in size and have a skull with an Archaeopteryx-like profile, a relatively small number of caudal vertebrae, a derived should girdle similar to Archaeopteiyx, a proportionately long forelimb, a pelvic girdle similar to basal birds, and a pes showing some arboreal features. The Liaoning dromaeosaurids display a diverse morphology of integumentary structures, including plesiomorphic single and natal-down-like filaments, and derived pennaceous feathers along the hindlimb. These discoveries provide the strongest evidence to date that feathers evolved before the origin of birds and flight. In particular, the morphology and distribution of the feathers on Liaoning dromaesaurids, among other features, strongly suggest that dromaeosaurids might have been able to parachute or even glide, representing a group of transitional animals between the cursorial non-avian theropods and volant birds. Sinovenator changae is the most basal troodontid found to date. It displays a number of features that are not found in more derived troodontids, but do occur in dromaeosaurs and avialans, such as a laterally directed glenoid fossa and opisthopuby. On one hand, Sinornithosaurus millenii, Microraptor zhanianus and Graciliraptor lujiatunensis display some troodontid-like features, such as the subarctometatarsalian pes, providing more evidence for the hypothesis that Dromaeosauridae-Troodontidae is a monophyletic clade. On the other hand, they and Sinovenator changae have more bird-like features than the more derived members of each clade, respectively, suggesting a closer relationships to birds. A numerical cladistic analysis of the interrelationships of coelurosaurian dinosaurs is performed. For the first time, this study: (1) quantitatively documents the relative significance of some taxa, (2) evaluates the affect of combining information from different parts of the body in reconstructing coelurosaurian evolution, and (3) compares the relative modification degree in different body parts within the Coelurosauria. This analysis suggests that Maniraptora is mainly composed of two lineages, an Alvarezsauridae-Therizinosauroidea-Oviraptorosauria lineage and a Paraves lineage. This result is more concordant with the current coelurosaurian fossil record because it suggests the major maniraptoran groups originated at times later than previously thought (earlier than Late Jurassic). The current analysis also supports a monophyletic Deinonychosauria containing the Dromaeosauridae and Troodontidae, but this relationship is weakly supported. A discussion of coelurosaurian evolution is presented based on results of this cladistic analysis. The quantitative study shows that at the bases of Coelurosauria, Maniraptora, and Paraves the relative modification degree is greater than at other nodes along the evolutionary history of the coelurosaurian dinosaurs. An examination of character distributions along the maniraptoran lineage reveals that major structural modifications toward avians were acquired in the early stages of maniraptoran evolution. Arboreal features are also observed in some non-avian maniraptorans. A new approach is proposed to infer the arboreality in some non-avian maniraptorans and birds. The quantitative study suggests there is an evolutionary trend toward arboreality within the Coelurosauria and the basal paraves might be arboreal animals. Some more derived paraves improved their arboreal adaptations later. This ecological transition is concordant with the independent phylogenetic analysis and the information from preserved integumentary structures.
页数	322
语种	中文
文献类型	学位论文
条目标识符	http://119.78.100.205/handle/311034/1756
专题	硕博论文古低等脊椎动物研究室
推荐引用方式 GB/T 7714	徐星. 辽西热河群的恐爪龙类化石及虚骨龙类的演化[D]. 中国科学院古脊椎动物与古人类研究所. 中国科学院古脊椎动物与古人类研究所,2002.

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