分类： 地球科学 >> 地质学 提交时间： 2018-02-26 合作期刊: 《古脊椎动物学报》
摘要： Reinvestigation of the Early Cretaceous eutherian mammal Endotherium niinomii Shikama, 1947, based on the impressions of the type specimen, casts made from the impressions, and the original description, indicates that E. niinomii is characterized by the following characters: decrease in size from the m1 to the m3; a moderate height difference between the trigonid and talonid of lower molars; blunt lower molar cusps; the protoconid being the largest among the trigonid cusps; the paraconid being as tall as the metaconid; the p3 not being obviously reduced; and possible possession of five lower premolars. These characteristics clearly distinguish E. niinomii from other known Cretaceous eutherians, and support its taxonomic identity as a valid taxon.
分类： 地球科学 >> 地质学 提交时间： 2017-09-28 合作期刊: 《古脊椎动物学报》
MAO Fang-Yuan
LI Chuan-Kui
MENG Jin
LI Qian
BAI Bin
WANG Yuan-Qing
ZHANG Zhao-Qun
ZHAO Ling-Xia
WANG Ban-Yue
摘要： Tooth enamel is composed of elongated, hexagonal crystallites of hydroxyapatite. Some crystallites are arranged into various regual structures and futher formed a composite structure in a hierarchical manner. The hierarchical system can provide a basis for analysis different levels of structural complexity from varitaiton of particular crystallite strucutes to variation of structural types throughout a individual’s dentition. The size, orientation, distribution and the packing patterns of crystallites are gene-comtrolled and have limited range of intraspecific variability. Thus, these microstructures provide considerable and reliable morphological characters that help understanding of external dental morphology in context of both phylogeny and function in vertebrates. Because teeth are highly resistant to weathering, mainly owing to their enamel covering, so that they were commonly preserved as fossils. This organic system, particularly their microstructures, has attracted more and more attention from vertebrate paleontologists and other morphologists. However, as already recognized by many previous studies, some terminologies of the enamel microstructures have been complex and used inconsistently. Although considerable effort has been made to study enamel microstructures in China during the last few decades, a standard terminology of enamel microstructures in Chinese has not be formally brought into line with that in English literatures. Here we intend to introduce and systematize the relevant terminology used in the study of enamel microstructures and translate them into Chinese, in hoping that this systematic effort will enhance researches of enamel microstructures in China. 脊椎动物牙齿釉质显微结构具丰富的形态学特征，承载着系统发育和生物力学等方面的信息。本文在前人的研究基础上，试图系统地介绍牙釉质显微结构的基本内容，提出牙釉质研究中相关术语的中文译名建议，并对一些重要术语做了简要解释，供相关研究者参考，以期促进牙釉质显微结构研究的进一步发展。
分类： 地球科学 >> 地质学 提交时间： 2017-08-10 合作期刊: 《古脊椎动物学报》
摘要： A new crested theropod, Shuangbaisaurus anlongbaoensis gen. et sp. nov., is reported. The new taxon is recovered from the Lower Jurassic Fengjiahe Formation of Shuangbai County, Chuxiong Yi Autonomous Prefecture, Yunnan Province, and is represented by a partial cranium. Shuangbaisaurus is unique in possessing parasagittal crests along the orbital dorsal rims. It is also distinguishable from the other two lager-bodied parasagittal crested Early Jurassic theropods (Dilophosaurus and Sinosaurus) by a unique combination of features, such as higher than long premaxillary body, elevated ventral edge of the premaxilla, and small upper temporal fenestra. Comparative morphological study indicates that “Dilophosaurus” sinensis could potentially be assigned to Sinosaurus, but probably not to the type species. The discovery of Shuangbaisaurus will help elucidate the evolution of basal theropods, especially the role of various bony cranial ornamentations had played in the differentiation of early theropods. 报道了具嵴冠的兽脚类恐龙一新属种，安龙堡双柏龙(Shuangbaisaurus anlongbaoensis gen.et sp. nov.)。双柏龙发现于云南省楚雄彝族自治州双柏县下侏罗统冯家河组中，保存了部分头骨带下颌。双柏龙沿两侧眼眶背缘向上有嵴冠发育，这在其他兽脚类中未曾报道过。与其他早侏罗世体型较大且具一对矢状嵴冠的兽脚类(双嵴龙属和中国龙属)相比，双柏龙还独具一些特征组合，如相对较高的前颌骨体、抬高的前颌骨腹缘、后腹向延伸的轭骨后突及较小的上颞孔。比较研究表明，尽管中国“双嵴龙” (“Dilophosaurus” sinensis)可能应归入中国龙属(Sinosaurus), 但未必属于模式种。双柏龙的发现将有助于研究基干兽脚类的演化，尤其是各类头骨骨饰在其中的作用。
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