Les continents péri-atlantiques au crétacé supérieur: Migrations des faunes continentales et problèmes paléogéographiques

Terrestrial vertebrates offer possibilities of reconstructing the migrations by land-routes followed during the late Cretaceous on the peri-Atlantic continents (North America, South America, Europe, Africa). South America and Africa were not separated before the Aptian. Later, migrations could still have occurred between Africa and South America during the late Cretaceous by a land-route (probably discontinuous) situated on the Rio Grande Rise-Walvis Ridge barrier; it is not impossible that some amphibia used this route. In Laurasia, two provinces were largely separated during the early part of the late Cretaceous: Euramerica and Asiamerica in the terminology of Cox (1974), (that is, Europe plus eastern North America and Asia plus western North America). During the latest Cretaceous, western North America became connected with Euramerica, but probably separated from Asia. During the latest Cretaceous, a route, probably terrestrial, permitted important faunal exchanges between South America and Laurasia; this connection was situated in the Caribbean region, perhaps where Central America is today. Limited faunal exchange occurred between Euramerica and North Africa.     

The most primitive lower tetrapod fauna in China

A comprehensive analysis of the fauna indicates that three vertebrate assemblage zones existed in the Upper Permian of China. Among them the Dashankou lower tetrapod fauna consisting mainly of therapsids is the most primitive and abundant one. It is more closely related to Zone II of Russia than to theEodicynodon Assemblage Zone of South Africa. Zone II of Russia in the Late Permian played a role of bridge for the dispersal of tetrapods from North America to South Africa and China at that time     

中央山系大别-东秦岭和东昆仑造山带最古老岩系变质过程对比

大别造山带、东秦岭造山带和东昆仑造山带是中国中央山系的主要构成部分,每个造山带古老岩系的变质作用过程各具特色．大别山最古老岩系大别岩群于印支期陆内俯冲碰撞,发生了区域性的中偏高压区域变质作用,顺时针型ｐｔ轨迹上ｔｍａｘ和ｐｍａｘ近于同时达到,退变质轨迹段斜率陡,埋深后受构造驱动快速抬升到上中地壳．东秦岭最古老岩系秦岭岩群在晋宁期（约１．０Ｇａ前）初始板块构造总背景下发生强烈的中压型碰撞变质作用,顺时针型ｐｔ轨迹上ｔｍａｘ在压力大幅度降低的过程中达到,反映弧陆碰撞增厚后深埋岩系受重力均衡抬升;至加里东期,秦岭岩群再次在板块构造的总背景下发生岛弧型变质,局部叠加中压型接触变质作用;晚海西以来北秦岭东段缺乏高于低角闪岩相条件的区域变质作用记录．东昆仑造山带最古老岩系于吕梁或早吕梁期发生中压碰撞区域变质,主体为角闪岩相,局部高角闪岩相－麻粒岩相条件,造山带剥露较浅使低压变质带得以良好保存．     

A coastal reservoir of terrestrial resources for neanderthal populations in north‐eastern Iberia: palaeoenvironmental data inferred from the small‐vertebrate assemblage of Cova del Gegant,Sitges, Barcelona

Coastal areas as reservoirs of resources for hominid groups have been widely studied in recent years. These areas combine marine with terrestrial and wetland resources and would have been optimum sites for hominids, including Neanderthals. This is the case with the Cova del Gegant, a cave that today opens directly onto the Mediterranean Sea and is located in the north‐eastern Iberian Peninsula. The geomorphological evolution of the Massis del Garraf has provided evidence that during the late Pleistocene there was a littoral platform between 8 and 13 km wide in front of the Cova del Gegant. Within this framework, the data derived from analysis of the small vertebrates and large mammals recovered from Cova del Gegant, including taxa currently absent from the Massis del Garraf, suggest that the landscape surrounding the cave provided a richer terrestrial ecosystem for Neanderthals than is available in this zone today. Analysis of the small‐vertebrate association from the cave reveals that the landscape surrounding the cave was dominated by woodland‐edge and open environments and that the climate was Mediterranean. The results have been compared with the only Iberian site with similar characteristics to the Cova del Gegant, Gorham's cave (southern Iberia, Gibraltar), revealing differences and similarities in the landscape and climate on the basis of the small‐mammal assemblages as well as the differences in the accessibility to terrestrial mammalian resources for the Neanderthal groups. The landscape and the climate were reasonably similar at the two sites, but the differences in the accessibility of resources for the Neanderthals are directly related to the location of the sites and the coastal position. Whereas the Cova del Gegant was on a route of mammal migration (between the Ebro Valley and France) suited for securing terrestrial resources, Gorham's cave is located on a small peninsula with a lower abundance of terrestrial mammal resources. This is probably why the Neanderthal groups at Gorham's cave exploited marine resources, whereas there is no evidence of marine resources having been exploited at Cova del Gegant, even though the seashore was nearby. Copyright © 2011 John Wiley & Sons, Ltd.     

非海相白垩系年代学和对比

从1800年代初最早确定的白垩系定义起,白垩系就包括了海相和非海相白垩纪的地层和化石。白垩纪是一个全球性气候温暖、海平面高、构造和火山活动强烈的世界。此时,多块大陆分解,几乎所有海洋都已打开,形成了与现代相近的海陆分布的地理图案。这一变革导致了全球生物群的区域化,给全球对比带来了困难。白垩纪的全球年代地层表是主要依据菊石和微体生物(有孔虫和钙质超微浮游生物)化石,并与已完整建立的全球极性倒转年表和很多放射性同位素年龄相结合的产物。从孢粉到恐龙等各类非海相化石均已用于白垩纪生物地层学。此期专刊的特色是聚焦于区域或全球的孢粉(包括沟鞭藻)、大植物、甲壳类(包括叶肢介和介形类)、软体动物(包括腹足类和双壳类)和脊椎动物(包括硬躯体和足印)非海相白垩纪生物地层学和生物年代学。这些研究大大扩展了非海相白垩系对比的内容,并强调了将能取得更多进展的研究方向。非海相地层和化石群中直接夹有海相地层和化石的剖面/地区的非海相生物地层学更精确的研究,高分辨率的微体化石,特别是既出现于非海相又见于海相地层中的微体化石的微体生物地层学的进展,更多的直接与非海相生物地层学相关的放射性同位素和古地磁年龄的测试,非海相地层的高分辨率层序和旋回地层学分析及与非海相生物地层学对比的化学地层学的发展等,均将促进全球非海相白垩纪地层时代和对比,甚至以国际地质时标为准绳的全球非海相白垩纪地层对比框架表的建立。     

辽宁西部及邻区中侏罗世燕辽生物群脊椎动物化石研究进展

近年来,在中国辽宁西部、内蒙古东南部、河北北部中侏罗世髫髻山组和九龙山组中发现了丰富的脊椎动物、无脊椎动物和植物化石,这一化石群被称为燕辽生物群。燕辽生物群已正式命名的脊椎动物26属28种,包括鱼类1属1种、两栖类4属4种、有鳞类1属1种、翼龙类10属12种、兽脚类恐龙5属5种、哺乳类5属5种。燕辽生物群的脊椎动物化石对研究长羽毛兽脚类恐龙的演化、翼龙类的分类演化、滑体两栖类的分异等具有重要意义。虽然辽宁西部及邻区燕辽生物群脊椎动物的多样性不及同一地区早白垩世的热河生物群,但它为认识这一地区晚中生代生物群的演替提供了极为重要的依据。     

寒武纪大爆发与动物树的成型

由“真动物”构成的动物界（不包括海绵）通常被划分为双胚层动物、原口动物和后口动物3个亚界。寒武纪大爆发经历了爆发的前奏—序幕—主幕3个阶段,其中后两个阶段处于早寒武世初期（依次以小壳化石的首次辐射和澄江动物群爆发为代表）,另一个则发生在“寒武前夜”（即前寒武纪末期）,以伊迪卡拉生物群为代表。这次独特的三幕式大爆发分步完成了动物形态演化谱系树（简写为TOA）的成型。已有化石证据显示,动物树的3大主体或3个亚界的起源及其早期辐射分别发生于寒武纪大爆发这3个主要阶段。澄江化石库中发现的早期后口动物亚界涵盖了该亚界中所有6大分支（棘皮类、半索类、头索类、尾索类、脊椎类和绝灭了的古虫类）的原始类群,澄江动物群时代标志着寒武纪大爆发的顶峰,完成了动物树框架的成型,从而宣告了寒武纪大爆发的基本终结。其学术重要性超越了中寒武世的布尔吉斯页岩,因为前者位于动物树形成的“源头”,而后者仅代表此后的“一段流程”。在动物演化历史上4个最具转折意义的重大创新事件（即多细胞动物起源、两侧对称动物起源、后口动物起源和脊椎动物起源）中,第一个发生在伊迪卡拉纪甚至更早的时期,其余3个则可通过梅树村化石群和澄江化石群观察到其完成的主体过程。已灭绝的古虫动物门,是初具鳃裂构造的原始分节动物,作为由原口动物向后口动物过渡的一个珍稀“缺环”,很可能代表着后口动物亚界的一个根。古囊类兼有两侧对称的古虫类和一些原始棘皮动物的镶嵌体征,最可能代表棘皮动物的一个根。在早寒武世动物演化谱系中,后口动物的＂顶端类群＂的代表是被誉为“第一鱼”的昆明鱼目,目前已知包括昆明鱼、海口鱼和钟健鱼,它们具对眼、脊索与串珠状脊椎软骨共存的原始脊椎,?