东北那达哈达岭硅质岩中的三叠纪牙形刺

本文首次描述了采自黑龙江那达哈达岭硅质岩中的三叠纪牙形刺Ｎｅｏｓｐａｔｈｏｄｕｓｃｆ．ｄｉｅｎｅｒｙ,Ｎ．ｋｏｃｋｅｌｉ,Ｎｅｏｇｏｎｄｏｌｅｌｌａｍｏｍｂｅｒｇｅｎｓｉｓ,Ｃａｒｉｎｅｌｌａｍｕｎｇｏｅｎｓｉｓ,Ｍｅｔａｐｏｌｙｇｎａｔｈｕｓｃｆ．ｐａｒｖｕｓ,从而确定了硅质岩的地质时代。     

江西二叠-三叠系界线层的牙形刺及Hindeodus-Isarcicela的演化谱系

对江西修水清水岩乡东岭剖面和乐平沿沟剖面的再研究表明,ＨｉｎｄｅｏｄｕｓｐａｒｖｕｓＭｏｒｐｈｏｔｙｐｅ１在东岭剖面首现于大冶组的最低层位,生物地层界线与岩石地层界线一致,仅比事件地层界线高５－６ｃｍ。沿沟剖面Ｈｉｎｄｅｏｄｕｓｐａｒｖｕｓ带厚仅３６ｃｍ,其首现与岩石地层界线也一致。张克信等提出的Ｈ．ｌａｔｉｄｅｎｔａｔｕｓ→Ｈ．ｐａｒｖｕｓ→Ｈ．ｔｕｒｇｉｄｕｓ→Ｉ．ｉｓａｒｃｉｃａ的演化谱系需作进一步修正。依据华南的资料,本文第一作者提出新的演化谱系：Ｈ．ｌａｔｉｄｅｎｔａｔｕｓ→Ｈ．ｐａｒｖｕｓ→Ｉ．ｓｔａｅｓｃｈｅｉ→Ｉ．ｉｓａｒｃｉｃａ。Ｈ．ｔｕｒｇｉｄｕｓ并不在此演化系列中,它属Ｈｉｎｄｅｏｄｕｓ的另一分枝。二叠三叠系界线层的牙形刺应区分出浮游相与浅水相。在浮游相,牙形刺序列为：（１）ＣｌａｒｋｉｎａｃｈａｎｇｘｉｎｇｅｎｓｉｓＣ．ｄｅｆｌｅｃｔａ带,（２）Ｃ．ｃａｒｉｎａｔａ带,（３）Ｃ．ｐｌａｎａｔａ带。在浅水相,牙形刺序列为：（１）Ｈ．ｌａｔｉｄｅｎｔａｔｕｓ带,（２）Ｈ．ｐａｒｖｕｓ带,（３）Ｉ．ｓｔａｅｓｃｈｅｉ带,（４）Ｉ．ｉｓａｒｃｉｃａ带,（５）Ｈ．ｐｏｓｔｐａｒｖｕｓ带     

二叠-三叠系界线层的牙形刺与生物地层界线

在研究二叠－三叠系界线地层时,应严格地将事件地层界线与生物地层界线区分开来。而定义生物地层界线时,也不应与“过渡层”或“混生层”的概念相连。在浙江长兴煤山,“界线粘土”层的底界,应为事件地层界线,界线层２的中部应为生物地层界线,比事件地层界线高１５ｃｍ。二叠－三叠系生物地层界线应以ＨｉｎｄｅｏｄｕｓｐａｒｏｕｓＭｏｒｐｈｏｔｙｐｅｌ的首次出现为准。在Ｈ．ｐａｒｖｕｓＭ．１缺乏的地区可以Ｃｌａｒｋｉｎａｃｈａｎｇｘｉｎｇｅｎｓｉｓ,Ｃ．ｄｅｆｌｅｃｔｓ,Ｃ．ｄｉｃｅｒｏｃａｒｉｎａｔａ,Ｃｌａｒｋｉｎａｓｐ．ｎｏｖ,Ｈｉｎｄｅｏｄｕｓｌａｔｉｄｅｎｔａｔｕｓ,Ｈ．ｔｙｐｉｃａｌｉｓ．Ｈ．ｃｈａｎｇｘｉｎｇｅｎｓｉｓｓｐ．ｎｏｖ等种的绝灭和ＨｉｎｄｅｏｄｕｓｐａｒｖｕｓＭ．２,Ｈ．ｔｕｒｇｉｄｕｓ,Ｏｐｈｉｃｅｒａｓ,Ｃｌａｒａｉａｗａｎｇｉ首次出现作为确定二叠－三叠系生物地层界线的辅助标准。这一生物地层界线恰在连续的单相地层中,完全符合全球界线层型剖面点的要求。因此长兴煤山忠心大队剖面是世界上最好的二叠－三叠系全球界线层型剖面点（ＧＳＳＰ）。     

二叠-三叠系界线层的牙形刺与生物地层界线

在研究二叠－三叠系界线地层时，应严格地将事件地层界线与生物地层界线区分开来。而定义生物地层界线时，也不应与“过渡层”或“混生层”的概念相连。在浙江长兴煤山，“界线粘土”层的底界，应为事件地层界线，界线层２的中部应为生物地层界线，比事件地层界线高１５ｃｍ。二叠－三叠系生物地层界线应以ＨｉｎｄｅｏｄｕｓｐａｒｏｕｓＭｏｒｐｈｏｔｙｐｅｌ的首次出现为准。在Ｈ．ｐａｒｖｕｓＭ．１缺乏的地区可以Ｃｌａｒｋｉｎａｃｈａｎｇｘｉｎｇｅｎｓｉｓ，Ｃ．ｄｅｆｌｅｃｔｓ，Ｃ．ｄｉｃｅｒｏｃａｒｉｎａｔａ，Ｃｌａｒｋｉｎａｓｐ．ｎｏｖ，Ｈｉｎｄｅｏｄｕｓｌａｔｉｄｅｎｔａｔｕｓ，Ｈ．ｔｙｐｉｃａｌｉｓ．Ｈ．ｃｈａｎｇｘｉｎｇｅｎｓｉｓｓｐ．ｎｏｖ等种的绝灭和ＨｉｎｄｅｏｄｕｓｐａｒｖｕｓＭ．２，Ｈ．ｔｕｒｇｉｄｕｓ，Ｏｐｈｉｃｅｒａｓ，Ｃｌａｒａｉａｗａｎｇｉ首次出现作为确定二叠－三叠系生物地层界线的辅助标准。这一生物地层界线恰在连续的单相地层中，完全符合全球界线层型剖面点的要求。因此长兴煤山忠心大队剖面是世界上最好的二叠－三叠系全球界线层型剖面点（ＧＳＳＰ）。     

江西二叠—三叠系界线层的牙形刺及Hindeodus—Isarcicella的演化谱系

对江西修水清水岩乡东岭剖面和乐平沿沟剖面的再研究表明,Ｈｉｎｄｅｏｄｕｓ ｐａｒｖｕｓ Ｍｏｒｐｈｏｔｙｐｅ１在东岭剖面首现于大冶组的最低层位,生物地层界线与岩石地层界线一致,仅比事件地层界线高５－６ｃｍ,沿沟剖面Ｈｉｎｄｅｏｄｕｓ ｐａｒｏｕｓ带厚仅３６ｃｍ,其首现与岩石地层界线与一致。张克信等提出的Ｈ。ｌａｔｉｄｅｎｔａｔｕｓ→Ｈ．ｐａｒｏｕｓ→Ｉ．ｉｓａｒｃｉｃａ的演化谱系需作进一步修正。依     

四川江油渔洞子剖面下三叠统飞仙关组底部龙介类的古生态意义

三叠系龙介类化石在欧洲早有报道。在我国四川江油渔洞子剖面下三叠统飞仙关组底部牙形刺Hindeodus pavus带微生物岩中首次发现环节动物龙介类化石Spirorbisphlyctaena,与以蓝菌为主的自养型底栖微生物群落共生,是早三叠世生物复苏的先驱者。     

以牙形刺确定胡氏贵州龙（Kueichousaurus hui Yang）层的时代

贵州兴义顶效乡盛产胡氏贵州龙的地层产牙形刺Ｐａｒａｇｏｎｄｏｌｅｌｌａｐｏｌｙｇｎａｔｈｉｆｏｒｍｉｓ－ｐ．ｍａａｎｔａｎｇｅｎｓｉｓ动物群,其时代应为晚三叠世卡尼早期。     

吉林李家窑范家屯组中的二叠纪北温带牙形刺动物群

在吉林省九台市三台乡李家窑附近的二叠系范家屯组中采到一特殊的牙形刺动物群。多数牙形刺都较小,锯齿发育,齿脊细齿不愈合。由一些未见报道的新分子组成。本文描述了４个新种（Ｍｅｓｏｇｏｎｄｏｌｅｌｌａ ｃｈａｎｇｃｕｎｅｎｓｉｓ ｓｐ．ｎｏｖ．,Ｍ．ｊｉｌｉｎｅｎｓｉｓ ｓｐ．ｎｏｖ．,Ｍ．ｍｕｌｔｉｓｅｒｒａｔａ ｓｐ．ｎｏｖ．,Ｍ．ｐｓｅｕｄｏａｌｔｕｄａｅｎｓｉｓ ｓｐ．ｎｏｖ．）和３个未命名新种     

黔南下-中二叠统界线层的牙形刺--瓜达鲁平统底界在华南的确认

本文详细研究了贵州罗甸纳水剖面下－中二叠统界线、即瓜达鲁平统（Ｇｕａｄａｌｕｐｉａｎ）底界附近的牙形刺动物群,并自上而下划分为Ｍｅｓｏｇｏｎｄｏｌｅｌｌａ ｓｉｃｉｌｉｅｎｓｉｓ－Ｍ．ｐｈｏｓｐｈｏｒｉｅｎｓｉｓ,Ｍｅｓｏｇｏｎｄｏｌｅｌｌａ ｉｄａｈｏｅｎｓｉｓ－Ｍ．ｐｈｏｓｐｈｏｒｉｅｎｓｉｓ,Ｍｅｓｏｇｏｎｄｏｌｅｌｌａ ｇｕｊｉｏｅｎｓｉｓ－Ｍ．ｉｎｔｅｒｍｅｄｉａ和Ｍｅｓｏｇｏｎｄｏｌｅ     

江西长兴组顶部与大冶组底部牙形刺的再研究

本文描述了江西信丰铁石口镇古南桃江剖面和修水清水岩乡东岭剖面长兴组最顶剖与大冶组（或铁石口组）最底部粘土层的牙形刺共１属６种和亚种,并把长兴组最顶部和大冶组最底部粘土层分别归属于Ｃｌａｒｋｉｎａ ｃｈａｎｇｘｉｎｇｅｎｓｉｓ ｙｉｎｉ－Ｃ．ｍｅｉｓｈａｎｅｎｓｉｓ ｚｈａｎｇｉ和Ｃｌａｒｋｉｎａ ｍｅｉｓｈａ－ｎｅｎｓｉｓ ｍｅｉｓｈａｎｅｎｓｉｓ带,它们分别可与浙江长兴煤山标准剖面长兴组最顶部和     

泥盆纪最早期和最晚期珊瑚群研究的进展——兼论泥盆纪珊瑚的绝灭、复苏及其底栖组合

由于志留泥盆纪之间没有发生明显的生物更替现象,所以泥盆纪最早期（Ｌｏｃｈｋｏｖｉａｎ）的珊瑚仍保留着浓厚的志留纪珊瑚的色彩。真正的泥盆纪类型的珊瑚是从早泥盆世中期（Ｐｒａｇｉａｎ）才开始兴起的,至晚泥盆世早期（Ｆｒａｓｎｉａｎ）末惨遭绝灭。晚泥盆世晚期（Ｆａｍｅｎｎｉａｎ）的珊瑚却与石炭纪珊瑚有着较为密切的关系。晚泥盆世的珊瑚经历了绝灭残存复苏３个发展阶段。泥盆石炭纪之交,泥盆纪最晚期（Ｓｔｒｕｎｉａｎ）的珊瑚再遭绝灭,至石炭纪初代之于Ｔｏｕｒｎａｉｓｉａｎ型的珊瑚。正当华南锡矿山（相当于Ｆａｍｅｎｎｉａｎ早期）的珊瑚群罹难的时刻,新疆北部洪古勒楞（亦相当于Ｆａｍｅｎｎｉａｎ早期）却形成了Ｆ／Ｆ大绝灭后生物理想的避难所。     

广西凌云县罗楼地区早三叠世牙形石

罗楼地区下三叠统,经赵金科（１９５９）研究显示,最低层位为Ｖishnuites marginalis菊石带（Gyronitan阶）,张舜新（１９９０）研究广西凤山金下三叠统形石时,未发现最高的牙形石带,当前研究发现,罗楼地区下三叠统牙形石丰富,可识别出Ｈindeodus parvus,Isarciclla staeschei ,Neospathodus waageni,Neospathodus novaehel-landiae,Neospathodus homeri-Neospathodus triangularis,Chiosella timorensis6个牙形石带（组合带）,从而表明该地区不但存在下三叠统底部层位Ｏtoceratan阶,而且存在下三叠统最高的牙形石带,牙形石组合面貌和岩相显示,该牙形石动物群生活环境与田东县作登地区同属盆地相环境。     

浙江黄芝山剖面二叠-三叠系界线附近的牙形类序列及其地层对比

首次系统研究浙江黄芝山剖面二叠-三叠系界线附近的牙形类化石,共鉴定2属16种,并据此识别出5个牙形类化石带,从下至上依次为:Clarkina changxingensis changxingensis带,C.parasubcarinata带,C.chan-gxingensis yini-C.meishanensis zhangi带,C.meishanensis meishanensis带,Hindeodus parvus带。Hindeodus changxingensis,H.eurypyge,H.parvus分别在第15层、第18层底部、第18层中部依次出现,为确定该剖面二叠-三叠系界线在18-3层之底提供了依据。作者还讨论黄芝山剖面二叠-三叠系界线附近的牙形类序列与浙江煤山、伊朗剖面二叠-三叠系界线层牙形类序列的对比。     

川东北二叠纪长兴晚期微生物丘:大灭绝事件过程的征兆?

虽然二叠系-三叠系界线附近的微生物岩是研究生态环境转折期海洋环境的热点素材,但以往所发现的实例都赋存于显生宙最大灭绝事件界线之上,还未报道过位于灭绝界线之下的微生物岩。川东北地区长兴组上部发育骨架礁层位之上的微生物丘,其中以尖山微生物丘最为典型,具三个生长旋回。根据微生物丘地层中所含牙形刺,和有孔虫,其时代为长兴晚期,处于大灭绝界线之下,其顶部距Hindeodus parvus带7.5m。碳同位素及微量元素分析揭示,从晚二叠世晚期开始,海洋生态环境条件的幕式不稳定性就已经显现并持续发展,导致生物危机也呈多阶段性特征。川东北晚二叠世微生物丘记录见证了重大地质转折期将至时生物与环境的相互作用关系。     

安徽巢湖地区早三叠世菊石序列

由于地处低纬度下扬子碳酸盐缓坡台地较深水区 ,安徽巢湖地区的下三叠统由一系列泥、灰岩旋回层组成 ,并含有丰富的菊石化石。通过对巢北平顶山和马家山一带上二叠统顶部和下三叠统多条剖面的系统研究 ,建立了在华南乃至低纬度特提斯地区具有代表性的、以属级分类单位为基础的下三叠统菊石生物地层序列 (从下而上 ) :Ophiceras Lytophiceras带、Gyronites Prionolobus带、Flemingites Euflemingites带、Anasibirites带、Columbites Tirolites带和Subcolumbites带。在提议的全球印度阶 奥伦尼克阶界线层型候选剖面———巢湖平顶山西坡剖面上 ,Flemingites Euflemingites带之底与牙形石Neospathoduswaageni首现点比较接近 ,可以作为本界线主要辅助标志之一。记述采自该区上二叠统顶部及下三叠统 ,尤其是印度阶 奥伦尼克阶界线附近的一些具有年代地层意义的菊石化石资料 。     

AMMONOIDS AND THE TRIASSIC/JURASSIC BOUNDARY IN THE HIMALAYAS OF SOUTHERN TIBET

Abstract:  The sections of Germig in the Nyalam area, southern Tibet, provide a continuous exposure of ammonoid-bearing, uppermost Triassic and basal Jurassic strata. Eighteen species (three of them new) are described and illustrated: Choristoceras marshi Hauer , C. aff. marshi, C. cf. nobile Mojsisovics , C. nyalamense sp. nov., Eopsiloceras germigense sp. nov. , Pleuroacanthites aff. biformis (Sowerby) , Rhacophyllites sp., Nevadaphyllites cf. psilomorphus (Neumayr), Neophyllites sp. indet., Neophyllites cf. biptychus (Lange), Psiloceras tibeticum sp. nov., P. calliphyllum (Neumayr), Euphyllites cf. struckmanni (Neumayr), Discamphiceras pleuronotum (Canavari), Alsatites spp., Kammerkarites frigga , and K. sp. The ammonoid fauna shows a strong affinity to that of the Northern Calcareous Alps, although diversity in the Calliphyllum Zone is markedly lower. The ammonoid succession across the Triassic/Jurassic boundary is subdivided into four zones: the Rhaetian Marshi, the basal Hettangian Tibeticum, the lower Hettangian Calliphyllum, and the middle Hettangian Pleuronotum zones. It is the only known succession across the Triassic/Jurassic boundary in the Tethyan Realm that is not condensed. The Marshi and Calliphyllum zones are correlated with the same zones in the Northern Calcareous Alps. The Tibeticum Zone, a new local zone, is transitional between the Marshi and the Calliphyllum zones in that it yields both choristoceratids and psiloceratids. Its base is taken to mark the base of the Jurassic System in the eastern Tethys.     

Conodonts from the Early Triassic microbialite of Guangxi (South China): implications for the definition of the base of the Triassic System

We describe a new Early Triassic (Griesbachian) succession of conodont faunas from a high‐resolution sampling of the basal Early Triassic microbial limestone and the base of the overlying unit at the Wuzhuan section (Nanpanjiang Basin, Guangxi, South China). The microbial limestone records the earliest phase of the Early Triassic biotic recovery after the end‐Permian mass extinction. For the first time, rich conodont faunas are reported from within the microbialite. The faunas from Wuzhuan are largely dominated by anchignathodontids, including several Isarcicella species, which were previously documented only from strata above the microbialite. A total of 14 conodont species assigned to three genera is recorded from the Wuzhuan section. Starting from the base of the microbialite upwards, several species are sequentially added to the conodont assemblage. The alpha diversity peaks at the top of the microbialite. The conodont record in the considered microbialite interval at Wuzhuan is presumably unaffected by local ecological changes. It therefore more likely represents an evolutionary rather than an ecological pattern. We compare the Wuzhuan's conodont record with a well‐supported phylogenetic model and suggest that the sequence of first occurrences at Wuzhuan is the closest to the ‘true’ sequence of evolutionary events that took place during this Griesbachian radiation of anchignathodontids. Based on comparisons with the GSSP section at Meishan, we suggest further that the first occurrence of Hindeodus parvus in Meishan does not correspond to its first appearance datum.     

The biogeography of Early Triassic ammonoid faunas: Clusters, gradients, and networks

The aim of this paper is to quantitatively investigate the spatial and temporal biogeographical relationships of the recovery of ammonoid faunas after the Permian-Triassic mass extinction using three complementary numerical approaches among which is a new, non-hierarchical clustering strategy. The faunal data set consists of a taxonomically homogenised compilation of the spatial and temporal occurrences of ammonoid genera within 20 Early Triassic Tethyan and Panthalassic sites ranging from 40°S to 70°N in palaeolatitudes. In addition to hierarchical cluster analysis (hCA) and nonmetric multidimensional scaling (NMDS), we introduce a third, new non-hierarchical clustering technique allowing the visualisation of a nonmetric interassemblages similarity structure as a connected network constructed without inferring additional internal nodes. The resulting network, which we call a “Bootstrapped Spanning Network” (BSN), allows the simultaneous identification of partially or totally nested as well as gradational linear or reticulated biogeographical structures.The identified interlocalities relationships indicate that the very beginning of the Early Triassic (Griesbachian) corresponds to a very simple biogeographical context, representing a time of great cosmopolitanism for ammonoids. This context shifts rapidly to a more complex configuration indicative of a more endemic and latitudinally-restricted distribution of the ammonoids during the middle and late Early Triassic (Smithian and Spathian). From an evolutionary dynamic point of view, our results illustrate a very rapid (less than ca. 1.4 myr) Early Triassic recovery of the ammonoid faunas, in contrast to many other marine organisms. This recovery is linked with a marked increase in the overall biogeographical heterogeneity, and parallels the formation of a latitudinal gradient of taxonomic richness, which may be essentially controlled by the progressive intensification of the gradient of sea surface temperature. From a methodological point of view, we show that a BSN is a simple, intuitively legible picture of the nested as well as gradational taxonomic similarity relationships, hence providing a good synthesis (and additional insights) between hierarchical clustering and ordination in reduced space results.     

Large‐scale evolutionary trends of Acrochordiceratidae Arthaber, 1911 (Ammonoidea,Middle Triassic) and Cope’s rule

Abstract: Directed evolution of life through millions of years, such as increasing adult body size, is one of the most intriguing patterns displayed by fossil lineages. Processes and causes of such evolutionary trends are still poorly understood. Ammonoids (externally shelled marine cephalopods) are well known to have experienced repetitive morphological evolutionary trends of their adult size, shell geometry and ornamentation. This study analyses the evolutionary trends of the family Acrochordiceratidae Arthaber, 1911 from the Early to Middle Triassic (251–228 Ma). Exceptionally large and bed‐rock‐controlled collections of this ammonoid family were obtained from strata of Anisian age (Middle Triassic) in north‐west Nevada and north‐east British Columbia. They enable quantitative and statistical analyses of its morphological evolutionary trends. This study demonstrates that the monophyletic clade Acrochordiceratidae underwent the classical evolute to involute evolutionary trend (i.e. increasing coiling of the shell), an increase in its shell adult size (conch diameter) and an increase in the indentation of its shell suture shape. These evolutionary trends are statistically robust and seem more or less gradual. Furthermore, they are nonrandom with the sustained shift in the mean, the minimum and the maximum of studied shell characters. These results can be classically interpreted as being constrained by the persistence and common selection pressure on this mostly anagenetic lineage characterized by relatively moderate evolutionary rates. Increasing involution of ammonites is traditionally interpreted by increasing adaptation mostly in terms of improved hydrodynamics. However, this trend in ammonoid geometry can also be explained as a case of Cope’s rule (increasing adult body size) instead of functional explanation of coiling, because both shell diameter and shell involution are two possible paths for ammonoids to accommodate size increase.