Reuniting the “head hunted” Corythosaurus excavatus (Dinosauria: Hadrosauridae) holotype skull with its dentary and postcranium     

《Cretaceous Research》2017

A Corythosaurus skull (UALVP 13) was collected in 1920 from what is now Dinosaur Provincial Park in southern Alberta, Canada and was designated the holotype of Corythosaurus excavatus, a new hadrosaur species by Gilmore (1923). In 1992, a previously uncovered, weathered, headless skeleton was found. This was collected in 2012 by the University of Alberta as there was potential it could belong to the holotype skull. In addition, an isolated hadrosaur dentary had been found in 1992 close to the articulated postcranial skeleton and may be one of the missing jaws of Corythosaurus excavatus. The hypothesis that it may be the skeleton of the holotype of Corythosaurus excavatus is tested using anatomical information and statistical analyses. Statistical comparisons suggest it is possible that the skull and dentary belong to the same specimen. Furthermore, bivariate plots and percentage prediction errors also indicate that the postcranial material could belong to the UALVP 13 skull. Because many large vertebrate fossil specimens (even types) are not always collected in their entirety, this method may be used as a line of evidence to determine whether independently collected specimens potentially belong to the same individual. The problems described herein highlight the need to collect specimens in their entirety, and for good field documentation, including the spatial and stratigraphic context of all finds.  相似文献   

小质量AGB星热脉冲阶段氟的核合成     

刘永新  张波  彭秋和 《中国天文和天体物理学报》1996,(1)

本文计算并讨论了当13C以渐进注入方式进入氦燃烧壳层时，19F在小质量AGB星热脉冲中的核合成问题．采用小质量AGB星热脉冲的氢氦混合燃烧模型，中子源为13C（a,n）16O，质子则是脉冲开始时从氢燃烧壳层卷入的．对丰度的数值计算结果表明，在小质量AGB星的热脉冲中，19F是能够有效合成的，有效合成的温度T的范围为1．8≤D＜2．8（T8=T/108K）．采用小质量AGB星的挖掘模型，计算了AGB星大气中氟、氧等元素丰度的变化，较好地拟会了观测结果．对中子源的双脉冲机制，本文亦做了初步探讨．  相似文献   

广西栗木水溪庙不对称层状伟晶岩－细晶岩岩脉的成因讨论   总被引：4，自引：1，他引：4  

朱金初  李人科  周凤英  王汝成  熊小林  许红忠 《地球化学》1996,(1)

水溪庙不对称层状伟晶岩─细晶岩岩脉生根于黄玉钠长石花岗岩中，其底板部分多以钠质细晶岩为主，顶板部分多以钾硅质伟晶岩为主，中间部分则往往以上述二种岩性的韵律式互层为主。笔者认为，岩脉的母岩浆应该与黄玉钠长石花岗岩的母岩浆相同，是一种富含Ｆ、Ｎａ的残余花岗质熔浆。岩脉自底板至顶板在组分和结构上的规律性变化，与这种特殊熔浆在岩脉环境下的分异演化、Ｆ含量的涨落和黄玉的周期性晶出以及熔浆结晶的动力学机制有关。  相似文献   

三江平原沼泽湿地时空动态特征   总被引：3，自引：0，他引：3  

张树清  汪爱华  ZHANG Junyan  ZHANG Bai 《地理学报(英文版)》2003,13(2):201-207

1IntroductionThe wetland ecosystem is the latest one understood by humans and it is the most seriously damaged ecosystem (Williams, 1991). The Sanjiang Plain, located in northeast China, is the largest concentrated area of freshwater wetland in China. Since the 1950s, large-scale reclamation of the marsh in the Sanjiang Plain has been started. According to statistics, the natural marsh has lost about 80% of its total area. The marsh resources in the Sanjiang Plain decreased greatly and the…  相似文献   

榆林地区土地退化机制和调控   总被引：6，自引：0，他引：6  

刘彦随  张晓平  李宪文  Jay GAO 《地理学报(英文版)》2003,13(2):217-224

Yulin district is located in the transitional zone between Mu Us Desert and Loess Plateau of northern Shaanxi Province,thus it is particularly vulnerable to degradation due to its fragile ecosystem and intense human activites there,The purpose of hias study is to explore the mechanism,process and driving force of land degradation in area with vulnerable eco-environment within the context of increasing population and intensifying human economic activities,and then find out the patterns and countermeasures of how to control them using the economic and technological ways,In detail ,this study includes three main sections:the first section analyzes the mechanism,causes and characteristics of land degradation,which can be achieved by the typical field investigations and systematical analysis within the regional natural,social and econmomic context.Based on the technologies of remote sensing and GIS ,and combined with the modeling methods,the second section reveals the change characteristics of land use and its driving force from 1990 to 2000; AS to the third section ,feasible countermeasures of how to prevent the degradation and rehabilitate the regional ecology are propsed ,which are studed from the perspective of harmony between nature and economy,and the conception of regional sustainable development.  相似文献   

富锂氟花岗岩中存在岩浆成因铁/锂白云母的实验证据   总被引：3，自引：2，他引：3  

李福春  朱金初  饶冰  王年生 《地球化学》2003,32(1):75-80

通过花岗岩—HF—H20体系的熔化—结晶实验，在570—700℃、100MPa条件下获得了与淬火玻璃共存的石英 碱性长石 云母 萤石的矿物组合。电子探针分析结果表明，实验产物中除黑云母外，还有一部分为铁白云母和锂白云母，这说明浅色云母可以形成于岩浆条件，同时为自然界中存在岩浆成因锂白云母花岗岩和二云母花岗岩提供了新的实验证据。  相似文献   

湘东北原生钴矿成矿地质条件分析   总被引：4，自引：0，他引：4  

宁钧陶 《湖南地质》2002,21(3):192-195,200

湘东北普乐及横洞原生钴矿床均赋存于长平断裂带F2主干断裂下盘构造热液蚀变岩带中。区域性长平断裂带为岩浆侵入和成矿物质运移提供了通道和空间；燕山期中酸性岩浆侵入为成矿提供了物质和动热来源；F2下盘层间裂隙群是重要的容矿构造；脆性围岩则是赋矿层位。  相似文献   

JD-2F型井下地震计     

胡履端  周鹤鸣  张伟清  周海南 《地震地磁观测与研究》2005,26(1):73-77

JD-2F型井下地震计是在JD-2型深井地震仪的基础上，经过进一步的技术改进并引入电子反馈技术而研制成功的。它是为井下地震台的数字化改造而研制的，是JD-2型地震仪的替代产品。本文通过对比，重点介绍了它的主要技术指标及结构特点。  相似文献   

中纬电离层大尺度扰动的数值模拟          下载免费PDF全文

黄朝松 Kell.  MC 《地球物理学报》1997,40(3):301-310

利用计算机模拟研究了不同条件下中纬电离层F区大尺度扰动的时空演变.当存在幅度约为5％的初始扰动时,Perkins不稳定性能发展成为大尺度电离层不均匀体.大气重力波能触发Perkins不稳定性,在更短时间内增长成为大幅度电离层振荡.非均匀局部电场结构也能产生局部电离层的大幅度扰动.本义的模拟表明,中纬电离层大尺度扰动主要表现为磁通管内等离子体沿磁力线的振荡.模拟结果与观测现象符合得很好.  相似文献   

Theory of thermospheric waves and their ionospheric effects     

S. B. Leble 《Pure and Applied Geophysics》1988,127(2-3):491-527

The analytical aspects of the internal thermospheric waves (IW) theory development are reviewed. The statement of the problem is discussed: the choice of the boundary and initial conditions. Special attention is paid to the upper boundary, the existence of which is the direct consequence of the molecular free way growth with height. The model equations for long waves are derived which take into account dissipation, spherity and rotation of the earth. The wave disturbance evolution is represented by the mode dynamical variables with the characteristics for thermospheric waveguide vertical structure. Nonlinearity of general hydrothermodynamic system leads to mode interaction. Therefore the mode coefficient functions satisfy the system of equations that generalizes the system of coupled KdV. As part of the manifestations of nonlinearity, the mean field generation problem by the quasiperiodic IW is discussed. The analytical F2-ionosphere effect model is represented. The model is based on the ambipolar diffusion equation. The calculated results of F2 maximum height variations during magnetospheric substorms are compared with the empiric model data.  相似文献