鄂西早三叠世南漳-远安动物群地层分布特征

在区域地质调查的基础上,以远安张家湾嘉陵江组剖面为重点,通过对南漳和远安交界地区下三叠统嘉陵江组剖面测制和多处化石点考察,重新厘定研究区内嘉陵江组岩性特征.认为研究区内的嘉陵江组划分为3个岩性段更为合理,产南漳-远安动物群的纹层状灰岩段位于二段顶部.通过系统化石发掘和张家湾剖面详细描述,初步查明了南漳-远安动物群的垂向...     

湖北蒲圻地区晚二叠世晚期至早三叠世岩石地层格架

蒲圻凤凰山、荆泉山两地晚二叠世晚期至早三叠世地层划分为三个层序：晚二叠世晚期至早三叠世早期的Ⅱ型层序、早三叠世中期的Ⅰ型层序和早三叠世晚期的Ⅱ型层序，该层序划分可与Ｍａｒｚｏｌｆ（１９９３）在ｄｏｌｏｒａｄｏ Ｇｒｅａｔ Ｂａｓｉｎ同期地层的层序划分对比相当。还讨论了副层序组合堆积型式、Ⅰ型或Ⅱ型层序界面及凝缩段的概念理解和实践操作等问题。     

早三叠世南漳—远安动物群研究进展

南漳-远安动物群是分布在湖北省南漳县和远安县的早三叠世海生爬行动物生物群。关于该动物群的研究开始于上世纪50年末,至今的研究历史分为两个阶段并取得重要成果。文章梳理了南漳-远安动物群的研究历程,从动物群的产出层位、海生爬行动物组合特征和生态特征三个方面介绍了南漳-远安动物群近年来取得的进展。这些进展表明,南漳-远安动物群所代表的早三叠世末期海生爬行动物的物种多样性和生态多样性已经高度发展,为研究二叠纪末生物大灭绝之后生物复苏进程提供了重要依据。研究成果的转化与应用,对促进化石产地和国家地质公园建设具有极大地促进作用。     

湖北黄石早三叠世的遗迹化石及其古环境意义

系统研究了湖北黄石新下陆下三叠统嘉陵江组碳酸盐岩地层中6个属的遗迹化石: Helminthopsis, Palaeophycus, Phycodes, Planolites, Rhizocorallium, Scalarituba,确认上述遗迹化石属于Cruziana遗迹相,依据风暴沉积及遗迹化石的组合推断嘉陵江组沉积序列是正常潮坪、浅海陆棚、浅水蒸发岩的沉积旋回.黄石地区的遗迹化石与美国西部弗吉尼亚早三叠世早期到晚期的演化特征以及前寒武纪-寒武纪之交、晚泥盆世弗拉期-法门期之交的遗迹化石所显示的演化特征颇为相近,这一耦合现象可能与生物-环境的系统演化有关.     

湖北早三叠世鱼龙前肢化石新材料及对比讨论

杨钟健和董枝明曾在1972年指出中国发现的早三叠世鱼龙Chaohusaurus geishanensis与欧洲的Grippia前肢和头部相似,具有系统关系。但后来中国该时代鱼龙类化石大多前肢特化或不完整,难以进一步对比研究。本文记述了湖北下三叠统嘉陵江组中发现的2件较完整的鱼龙前肢化石新材料,对中国的古老鱼龙类相关信息进行了补充。通过形态学对比,认为湖北被归入Chaohusaurus的早三叠世鱼龙前肢总体特征与同属的Ch.geishanensis接近而与Ch.chaoxianensis有明显差别,而且其以相对较大的个体、间中骨挤压变形以及豌豆骨发育等特征表现出与Grippia、Utatsusaurus、Parvinatator等其他早三叠世鱼龙类前肢的相似性。据此分析推测,早三叠世鱼龙类可能存在两个演化方向。即在二叠纪末大灭绝(EPME)事件后不久,鱼龙类起源并在奥伦尼克期出现分化,一部分个体相对较大、前肢未特化、运动能力较强的鱼龙类实现了跨区交流,另一些个体相对较小、前肢特化、运动能力较弱的鱼龙类则成为地方性(东特提斯区)的独立演化分支。但两者之间的系统发生关系以及Chaohusau...     

塔里木盆地早三叠世疑源类的发现

笔者根据孢子花粉的研究，首次确定了塔里木盆地钻井中三叠系的存在。在早三叠世孢子花粉组合中共生了以具刺的Ｖｅｒｙｈａｃｈｉｕｍ和Ｍｉｃｒｈｙｓｔｒｉｄｉｕｍ为主的疑源类化石，共有１２个属，１１个老种和２个新种。该盆地下三叠统过去认为是陆相沉积，而具刺疑源类是生长在海水中的浮游生物，因此具剌疑源类的广泛发现，说明该盆地早三叠世沉积时，距海较近，有海水侵入。     

长江三峡地区晚二叠世晚期—早三叠世早期沉积特征

晚二叠世长兴期时长江三峡地区位于浅水碳酸盐台地怀深水盆地结合带，沉积相变化大，主要有五种沉积类型：灰峄型；灰岩－炭质灰岩－泥岩型；灰岩－硅质岩－泥岩型；炭质灰岩－泥岩型；硅质岩－泥岩型；第一种类型为台地边缘沉积，第二，三种为台前斜坡沉积，第四，五种为深水盆地沉积。     

湖北兴山峡口早三叠世双壳类生物地层及古群落分析

湖北兴山峡口剖面位于早三叠世中扬子碳酸盐缓坡较深水区域, 是我国海相二叠系-三叠系典型剖面之一.根据该剖面下三叠统大冶组地层中双壳类的垂直分布, 结合区域资料, 将该地区早三叠世早期双壳类划分为4个生物地层单位, 自下而上依次为: (1) Claraiastachei-C.griesbachi带; (2) Claraia concentrica-C.hubeiensis带; (3) Eumorphotis multiformis-E.in-aequicostata带; (4) Posidoniacircularis-P.cf.wengensis带.为了探讨生物群面貌与环境演变之间的关系, 根据双壳类的产出特征及其赋存岩石的沉积特征, 建立了3个化石群落: (1) Claraiaconcentrica-C.aurita群落; (2) Eumorphotis inaequicostata-E.multiformis群落; (3) Posidonia circularis群落.早三叠世早期双壳类群落演替, 反映了该地区早三叠世早Dienerian期海水曾一度变浅, 之后随着海侵的扩大, 水体逐渐加深.二叠纪末生物大灭绝后海洋环境动荡, 可能是早三叠世海洋生态系复苏过程延长的重要原因.      

准噶尔早三叠世古地理及古气候特征

二叠纪和三叠纪是衔接古生代和中生代的两个地质时代,在这个地质时期内,世界上出现了板块大联合--泛大陆,发生了地史上最大规模的生物更替。从早二叠世开始到晚二叠世,世界上发生过巨大规模的海退,显示出古气候、古海洋方面许多变化,对古地理环境造成了巨大的影响。早三叠世古地理和古气候的研究,对阐明古生代与中生代地质发展史、生物演化及沉积环境均有重要的意义。 准噶尔早三叠世古地理,经过新疆地质矿产研究所两轮古地理图的编制（1985-1987年,1999-2000年）已经有了许多比较深入的认识,本文侧重在早三叠世古地理及古气候与…     

云南罗平中三叠统一海龙类新材料

海龙类前肢化石标本(YIGM SPC V 0832-2)采自于云南省罗平县新寨一带中三叠统安尼阶(Pelsonian亚阶)关岭组二段顶部.其不仅为海龙类在罗平生物群中的首次发现, 而且为长颈型海龙的最早记录.该海龙类新材料虽然保存不全, 但是仍具有一些独特的特征: 桡骨远端两侧边缘平行; 尺骨远端扩展; 11个硬骨化腕骨; 第三掌骨近端内侧缘发育横突; 指式为2-3-4-4-4(?).虽然上述特征尚不足以建立一海龙类新属种, 但是仍然反映了部分海龙类单元在向海洋适应辐射的过程保留有原始爬行类的特征.这些原始特征暗示着部分海龙类可能以营陆生生活为主.      

A New Specimen of Shansisuchus shansisuchus Young, 1964 (Diapsida: Archosauriformes) from the Triassic of Shanxi, China

Shansisuchus shansisuchus Young,1964 was restudied on the basis of a new specimen.Some anatomical features that were either briefly or not described at all in the original study were detailed.The new specimen not only provides further information on the skull anatomy and the vertebral column but also expands the range of the geographical distribution of the taxon.With new information,the diagnosis of S.shansisuchus was emended and its phylogenetic relationships were further analyzed.S.shansisuchus differs from other archosauriforms primarily in the presence of a large subnarial fenestra anterior to the antorbital fenestra,tongue-in-groove articulations between the ascending process of the premaxilla and nasal and between the premaxilla and maxilla,a tall and posterodorsally directed ascending process of the maxilla,a knee-shaped process of the postorbital projecting into the orbit,a broad descending process of squamosal distally well forked and a large,deeply bow-shaped intercentrum tightly anchoring/capping the sharp ventral edges of two neighboring centra together in cervical and at least first eight dorsal vertebrae.With additional information derived from the new specimen,the phylogenetic relationships of S.shansisuchus were reanalyzed;it is closely related to Erythrosuchus-Vjushkovia clade.     

海龙类化石在云南泸西上三叠统的发现

采自云南泸西县城附近小兴安村晚三叠世卡尼期小凹组的海龙化石,是关岭生物群海龙类化石在贵州关岭之外地区的首次发现。该化石标本共保存有9枚较好的背椎骨,21条完好的肋骨及若干腹肋。靠近头部的4枚背椎骨为有次序的自然排列。背椎椎体长约12cm,椎体横突发育,椎体腹侧轻微凹入,呈双凹形,近似圆形。这一特征与鱼龙类脊椎骨明显的双凹特征有所区别,故暂且将其归于海龙类。新采集的该化石标本为探讨海龙类的古地理分布,以及寻找规律生物群新化石产地提供了信息。     

Early Cretaceous choristoderes (Diapsida,Choristodera) from Siberia,Russia

There are ten known Lower Cretaceous localities for skeletal remains of choristoderes in Siberia (Russia). Choristoderan remains at all these localities are represented by isolated bones, usually by isolated vertebrae of Choristodera indet. Three choristoderan taxa in two geological units were identified: the non-neochoristodere Khurendukhosaurus sp. (possibly closely related to the long-necked Sino-Japanese hyphalosaurids) from the Murtoi Formation, Transbaikalia; cf. Khurendukhosaurus sp. and the “Shestakovo choristodere” with possible neochoristoderan affinities from the Ilek Formation, Western Siberia. All these three choristoderan taxa had a microanatomical organization of vertebrae similar to that of in advanced large neochoristoderes (vertebral centra with tight spongiosa). The Siberian fossil record includes the westernmost (Shestakovo locality, Ilek Formation) and the northernmost (Teete locality, the Sangarian Group) occurrences of the Early Cretaceous choristoderes in Asia. Like in other regions of Asia, Siberian localities are characterized by the absence of neosuchian crocodyliforms.     

Osteology and ontogeny of Early Cretaceous Philydrosaurus (Diapsida: Choristodera) based on new specimens from Liaoning Province,China

Choristoderes are a group of extinct diapsid reptiles that once occupied the freshwater systems in the Northern Hemisphere from the Middle Jurassic through the Miocene. The Early Cretaceous monjurosuchid Philydrosaurus from western Liaoning, China, represents a transitional morphotype between a broad-snouted (crocodile-like) and a narrow-snouted (gavial-like) skull during the evolution of Choristodera. New specimens of the taxon from the Early Cretaceous Jiufotang Formation include an incomplete braincase and a nearly complete juvenile skeleton; the study of these specimens provides new information on the braincase and ontogenetic change of the skeleton of this transitional monjurosuchid. In the braincase floor, the foramen internus canalis caroticus externus opens in a groove lateral to the constricted lateral aspect of the parasphenoid, and ventral exposure of this foramen differs from Champsosaurus, in which parasphenoid/pterygoid fusion completely encloses the canal. On the occiput, the vagus nerve foramen penetrates the basioccipital, while the two foramina for the hypoglossal nerve open at the exoccipital/basioccipital suture. Comparative study of the new juvenile specimen with adult Philydrosaurus reveals previously unknown developmental changes of the cranial and postcranial skeleton of this monjurosuchid. Ontogenetically, Philydrosaurus underwent a dramatic change of skull proportions, including elongation of the antorbital and postorbital regions, and elongation of the jaws, with a great increase of the number of marginal teeth. The lower temporal fenestra is entirely closed in early ontogeny, as in large, fully-grown adults.     

Chitinozoans from the Fenxiang Formation (Early Ordovician) of Yichang, Hubei Province, China

Chitinozoans collected from upper Tremadocian to lower Floian strata of Chenjiahe section, Yichang, western Hubei, China comprise six species belonging respectively to the genera Euconochitina including a new species, Euconochitina fenxiangensis, Lagenochitina and Bursachitina, together with Desmochitina sp. and Eremochitina sp. The chitinozoan succession across the interval is correlated with relevant conodont and chitinozoan biozones and two new regional chitinozoan biozones, the Lagenochitina destombesi Biozone and the Euconochitina symmetrica Biozone are proposed based on their stratigraphic ranges in the Fenxiang to Honghuayuan formations in the Chenjiahe section.