Middle-to-Late Jurassic terrestrial vertebrates of China: Systematics and geochronology

中国中晚侏罗世陆生脊椎动物：系统与地质年代学[i]: James M Clark， George Washington University；在世界范围内，对中晚侏罗世（距今1.76 - 1.56亿年前）陆生脊椎动物化石的了解非常少，但中国西北石树沟组保存了大量来自这个时代的关节骨骼。这是现代陆地脊椎动物历史上的一个重要时期，因为最古老的现代哺乳动物、蜥蜴、海龟和蝾螈都是在这个年代或稍早的时候出现的，而侏罗纪晚期最古老的鸟类始祖鸟的出现表明鸟类大约在这个时期进化。在白垩纪繁盛的主要恐龙谱系（角龙、甲龙、鸟脚亚目、新蜥脚类和虚骨龙）也出现在这个时期。2004年至2006年，由美国国家科学基金会资助，广东大学和中国科学院对石首沟组进行了联合考察，收集了450多种脊椎动物化石，并记录了石首沟组的地质情况。我们对岩石进行了放射性定年，表明该地层跨越中-上侏罗统边界。我们发现了最古老、最原始的霸王龙（Guanlong wucaii）和角龙（Yinlong downsi）恐龙，亚洲最早的角龙兽脚亚目恐龙（Limusaurus inextricabilis），以及最古老、最原始的奇怪的alvarezsaurid兽脚亚目恐龙。这些化石为鸟类起源提供了重要证据，为兽脚亚目动物手指的身份提出了新的假设，并记录了始祖鸟之前1000万年鸟类近亲的多样化。两个特别的地点保存着挖矿的证据，这是一种非常不寻常的保护环境。在此，我们要求支持以下工作：1)研究未描述的化石，包括一种基底蜥蜴、一种原始哺乳动物、一种罕见的新龟和一种新的手盗龙兽脚亚目恐龙的接近完整的骨骼；2)准备几种重要恐龙物种的详细描述；3)对石树沟组底部岩石、准噶尔盆地其他地区当代岩石和中国四川中侏罗统沙溪庙组岩石进行放射性测年（ID-TIMS）。4)继续寻找石树沟组特别是石树沟组下部的化石。该项目的参与者包括地球科学领域代表性不足的群体（两名女性和一名美洲原住民）。

Middle-to-Late Jurassic terrestrial vertebrates of China: Systematicsand geochronologyPI: James M Clark, George Washington University Co-PIs: Catherine A. Forster, GWU; Xu Xing, Chinese Academy of Sciences Land-living vertebrate fossils from the Middle and early Late Jurassic (176-156 million years ago) are very poorly known worldwide, but the Shishugou Formation of NW China preserves abundant articulated skeletons from this age. This is an important time in the history of modern land vertebrates, because the oldest occurrences of modern mammals, lizards, turtles, and salamanders are this age or slightly older, and the presence of the oldest bird Archaeopteryx later in the Jurassic indicates that birds evolved at about this time. The major lineages of dinosaurs that flourished in the Cretaceous (ceratopsians, ankylosaurs, ornithopods, neosauropods, and coelurosaurs) also appear at this time. From 2001-2006 joint expeditions by GWU and the Chinese Academy of Sciences to the Shishugou Formation, funded in 2004-2006 by the NSF, collected over 450 vertebrate fossils and documented the geology of the formation. We radiometrically dated rocks indicating the formation spans the Middle-Upper Jurassic boundary. Among our discoveries are the oldest and most primitive tyrannosauroid (Guanlong wucaii) and ceratopsian (Yinlong downsi) dinosaurs, the first ceratosaurian theropod dinosaur from Asia (Limusaurus inextricabilis), and the oldest and most primitive member of the bizarre alvarezsaurid theropods. Fossils in this collection bear important evidence on the origin of birds, generating a new hypothesis for the identity of the fingers present in theropods and documenting the diversification of the closest relatives of birds 10 million years prior to Archaeopteryx. Two extraordinary sites preserve evidence of miring, a highly unusual preservational milieu. Here we request support for 1) studies of undescribed fossils, including nearly complete skeletons of a basal lizard, a primitive mammal, an unusual new turtle, and a new maniraptoran theropod dinosaur, 2) preparation of detailed descriptions of several important dinosaur species, 3) radiometric dating (ID-TIMS) of rocks at the base of the Shishugou Formation, in contemporary rocks elsewhere in the Junggar Basin, and in the Middle Jurassic Shaximiao formations of Sichuan, China, and 4) continued exploration for fossils in the Shishugou Formation, especially in the lower part of the formation. Participants in this project include underrepresented groups in Earth Sciences (two females and a native American).