广西早泥盆世节甲鱼类及胴甲鱼类化石及华南早泥盆世脊椎动物生物地层对比

描述了早泥盆世的3个属种,其中节甲鱼类Yujiangolepisliujingensisgen．etsp.nov.采自广西六景,Buchanosteussp．及胴甲鱼类？Chuchinolepissp.采自广西玉林。该3件标本均产自海相地层中,与海相无脊椎动物化石共生。还讨论了华南区几个主要产脊椎动物化石（包括脊椎动物微体化石）剖面的生物地层对比。     

Devonian features in Ludlovian graptolites — no guide to ancestry

A diverse group of Ludlovian Monograptus species is characterized by the retarded growth of thecal hoods, either proximally [ M. colonus (Barrande), M. chimaera (Barrande) and M. haupti Kühne] or throughout the rhabdosome [M. micropoma (Jaekel)]. In all these species the hoods are secondary structures, i.e. later growth additions to the thecae. By contrast, in the Devonian Monograptus species the thecal hoods are primary structures, i.e. the outward extension of the dorsal thecal wall. and are formed by undelayed growth that typically is completed before growth of the succeeding theca begins. It is among Ludlovian ( M. uncinatus Tullberg) and Pridolian ( M. simih Přibyl) forms with homologous hoods that the roots of the majority of the Devonian Monograptus species might be found. The Ludlovian M. micropoma and M. haupti should not be affiliated to the group of Monograptus vomerinus (Nicholson), which is highly characteristic of, and restricted to, the late Llandovery and Wenlock graptolite faunas.     

REMARKS ON THE STRATIGRAPHY AND MORPHOLOGY OF PRAGUIAN AND PROBABLY YOUNGER MONOGRAPTIDS

Praguian and probably younger graptoloids as well as the early Lower Devonian (Lochkovian) graptoloids are known from all continents except Antarctica and South America. At least five to six graptolite zones can now be distinguished in the Lower Devonian. In comparison with the Lochkovian faunas, the medial to late Lower Devonian graptoloid communities are considerably impoverished and composed exclusively of Monograptus species of the M. uncinatus group. Lino-graptus and Abiesgraptus , which are characteristic of much of the Lochkovian, are lacking in Praguian (and younger) strata. Monograptus pacificus from the southeast Alaskan Karheen Formation appears to be the youngest true graptolite known to date, possibly having a stratigraphic position not far away from the Lower/Middle Devonian boundary.     

Dissepiments in the graptolite Monograptus turriculatus

An example of the graptolite Monograptus turriculatus (Barrande, 1850) from the crispus Biozone (Silurian, Llandovery) of the Girvan district, Scotland, shows the first recorded instance of dissepiment formation in graptoloid graptolites. The dissepiments are formed by the fusion of thecal spines with the dorsal wall of the adjacent part of the succeeding whorl of this spiral graptolite. The formation of these structures appears easiest to envisage using models of the graptolite colony that do not involve extrathecal tissue. □ Graptolithina , Monograptus, morphology, functional morphology, Silurian, Llandovery.     

Evolution in Monograptus priodon

Biometric analysis of the Silurian graptolite Monograptus priodon (Bronn) from Arctic Canada and the British Isles shows that the length of the sicula and the rhabdosome width at the level of theca 5 undergo a progressive increase from latest Llandoverian to late Wenlockian time. This change is attributed to sympatric evolution within the species. Monograptus flemingii (Salter) may have evolved elsewhere from priodon stock and migrated later into the two regions. Monograptus riccartonensis Lapworth probably ranges from latest Llandoverian through the Wenlockian, and may have been ancestral to the Ludlovian to Devonian Monograptus lineages.     

Silurian (Wenlock–ludlow) Graptolites from Bolivia

Well preserved middle to upper Silurian (Wenlock–Ludlow) graptolites from Bolivia are described for the first time. Generally monospecific graptolite faunas, of species largely endemic to South America, are found in a few levels in the lower part of the Kirusillas, Rio Carrasco and Uncía formations. The oldest identified level yields specimens of Pristiograptus praedeubeli (Jaeger) and is referred to the upper Wenlock. Younger faunas belong to the Ludlow and include Saetograptus , Monograptus and Neodiversograptus specimens. These may be referred to the Gorstian (lower Ludlow). The fauna includes Saetograptus argentinus robustus ssp. nov. and Monograptus bolivianus sp. nov.     

LOWER DEVONIAN GRAPTOLITES FROM SOUTHEASTERN ALASKA

The youngest zones of Monograptus occur in Devonian black shale and slate along the western shore of Prince of Wales Island and on Noyes Island, southeastern Alaska. The following five species of Monograptus, in close association with vascular plants and marine shelly faunas, indicate a Praguian, (Siegenian to Early Emsian), late Lower Devonian and possibly early Middle Devonian age: M. yukonensis Jackson & Lenz, M. n. sp. aff. yukonensis ? Jaeger & Stein, M. aeqimbilis notoaequakilis Jaeger & Stein, M. pacificus Jaeger n. sp. and M. craigensis Jaeger n. sp. The yukonensis zone containing M. craigensis in its upper part is followed stratigraphically higher by the M. pacificus zone – the youngest occurrence of Monograptus. The new species belong to the M. uncinatus group and, like most Praguian monograptids, have long dorsal tongues on their siculae. M. craigensis and M. pacificus increase to seven the number of species of Monograptus known from the Praguian. On the basis of the Alaskan material, the geographical distribution of M. aequabilis notoaequabilis now includes North America in addition to previously recorded occurrences in Australia, Southeast Asia, and Europe. This broad geographic distribution suggests that the last survivors of Monograptus had worldwide distribution and a rather uniform assemblage of species.     

Punctuated stasis and collateral evolution in the Devonian lineage of Monograptus hercynicus

The changes in the sicula of Early Devonian monograptid graptolite populations show a pattern that is described as punctuated stasis: two longer periods of stasis separated by a transitional population of shorter duration between them. The pattern differs from punctuated equilibrium in that anagenesis is involved rather than cladogenesis. The pattern has been observed in several widely separated areas (Nevada, Thuringia, Poland, Ural Mountains) and is an example of collateral evolution in graptolites. In this case, the collateral morphologic change occurs relatively rapidly in a large, globally distributed taxon. The study permits accurate correlation of the horizon of appearance of Monograptus hercynicus Pemer in the upper delta Zone (conodont zonation) of late Lochkovian age (Devonian) on a global scale. The partial integration of these two biostratigraphies constrains correlations between the shelly, shallow-water biofacies and the deeper graptolitic biofacies. The pattern of punctuated stasis has been discovered in Lower Devonian strata of central Nevada, where 22 horizons in sequence were sampled. Statistical analyses were performed on 13 characters encompassing measurements of the sicula, thecae, and rhabdosome. Most of these characters do not exhibit sustained trends or punctuated changes. However, sicular width exhibits an abrupt increase over a short stratigraphic interval and is used to classify members of the group into four quantitatively defined morphotypes. This natural perturbation in the pattern of change is used to divide the lineage into paleospecies. This makes the segments of the lineage easy to identify and imparts stability to the classification and precision in biostratigraphy. The variation studies enable the ranges of the morphotypes to be used to further subdivide the stratigraphic record of the late Lochkovian. □ Graptolites, Devonian, Lochkovian, evolution, punctuated stasis, biostratigraphy, MONOGRAPTUS, phylogeny.     

江西崇义早奥陶世茅坪组的笔石

记述早奥陶世茅坪组笔石9属25种,其中2新种.根据一些新材料的发现和笔石群的详细研究,将茅坪组笔石划分为3个带,即上部的Adelograptus-Clonograptus 带,中部的Aletograptus-Trograptus带,下部的Staurograptus-Anisograptus带.     

贵州思南奥陶纪末至志留纪初大息场组的笔石

贵州思南奥陶纪末至志留纪初大息场组的笔石研究结果表明,大息场组共产出笔石6属7种:Styracograptus chiai(Mu,1949),Normalograptus mirnyensis(Obut and Sobolevskaya,1967),Normalograptus ajjeri(Legrand,1977),Metaclimacograptus hughesi(Nicholson,1869),Avitograptus avitus(Davies,1929),Atavograptus atavus(Jones,1909)和Korenograptus laciniosus(Churkin and Carter,1970)。自下而上可识别出相当Dicellograptus complexus带、Akidograptus ascensus带和Cystograptus vesiculosus-Coronograptus cyphus带的3个含笔石地层带。虽然大息场组的笔石动物群分异度较低,但全都是上扬子区奥陶-志留系之交的常见属种,除S.chiai(Mu)之外,其它都是全球广布的物种。     

The Downton Series as the fourth Series of the Silurian System

A review of lithofacies and fossil distributions in the Downton strata of the Welsh Borderland and Wales indicates that these beds form a suitable basis for definition of a chronostratigraphical division of Series rank within the Silurian System. The basal boundary stratotype for the Downton Series is defined at the base of the Ludlow Bone Bed Member of the Downton Castle Sandstone Formation in a section at Whitcliffe Road, Ludlow. Shallow water marine sediments span the boundary, with no evidence of a measurable time break. Correlation of the base of the Downton Series from eastern North America through Baltoscandia and Poland suggests that it lies at or very close to the base of the Monograptus ultimus Biozone and thus approximates to the base of the Přiacute;dolí beds of Bohemia. This paper formed a submission to the Subcommission on Silurian Stratigraphy in May. 1981. □ Silurian, Downtown Series, standard subdivision, lithostratigraphy, biostratigraphy, chronostratigraphy, correlation.     

A chitinozoan morphological lineage and its importance in Lower Silurian stratigraphy

Margachitina margaritana is a distinctive, chain-forming chitinozoan taxon of the uppermost Telychian Stage (Llandovery Series) to lower Homerian Stage (Wenlock Series). M. margaritana is shown to be the end member of a morphological lineage that developed from Calpichitina densa via the intermediate Margachitina banwyensis sp. nov. A local M. banwyensis Biozone, which correlates with the upper lapworthi graptolite Biozone, is proposed for the Banwy River section. The morphological lineage described provides a tool for the enhanced subdivision of the uppermost Llandovery Series, which may prove global in extent. This research suggests also that the base of the Wenlock Series may correlate with a level below the centrifugus graptolite Biozone and it also brings into question the systematic status of Calpichitina and Margachitina, although both genera are retained herein.     

Chitinozoan biostratigraphy of the Upper Ordovician Fågelsång GSSP, Scania, southern Sweden

In the Fågelsång section, the new Global Stratotype Section and Point (GSSP) for the base of the Upper Ordovician Series, 22 samples from the E14 (a, b and c) and E15 outcrops have been studied for chitinozoans. They yield rich and rather diverse species assemblages of this microfossil group. The approximately 16-m-thick sampled part of the section can be subdivided, from bottom to top, into two biozones and a subbiozone: the Laufeldochitina stentor zone, the Eisenackitina rhenana subzone and the Lagenochitina dalbyensis zone. The boundary between the lowest biozone and the subzone is situated 1.7 m below the marker “Fågelsång Phosphorite” bed, thus only slightly lower (0.3 m) than the base of the Nemagraptus gracilis graptolite biozone, which defines the base of the Upper Ordovician Series. The base of the L. dalbyensis zone is located just above the Fågelsång Phosphorite, remarkably low compared to the graptolite biostratigraphy. It is evident that the chitinozoan biozonation provides an additional tool to recognise the base of the Upper Ordovician in this section. Furthermore, a distinct faunal change is shown across the phosphorite bed, possibly indicating a hiatus.     

内蒙古乌海大石门奥陶系牙形刺和Histiodella动物群发现的意义

本文描述了内蒙古乌海大石门剖面奥陶系的牙形刺动物群:下克里摩里组主要有Histiodella kristinae,H.holodentata,H.wuhaiensis sp.nov.,Polonodus newfoundlandensis和Paroistodus horridus等,应归属于中奥陶统达瑞威尔阶(Darriwilian)之Histiodella kristinae带,并在同一剖面上与笔石Pterograptus elegans带和Didymograptus murchisoni带下部相当;下克里摩里组顶部产Histiodella kristinae,Baltoplacognathus cf.reclinatus,Periodon aculeatus和Protopanderodus rectus等,所以大石门剖面的Histiodella kristinae带顶部可能已与北欧Pygodus serra带之底部相当;乌拉力克组底部的砾状灰岩透镜体产有牙形刺Pygodus anserinus?,Protopanderodus liripipus,Yangtzeplacognathus protoramosus和Dapsilodus viruensis等,其中Pygodus anserinus?Pa分子(器官种的一组成分子)的口面瘤齿列的瘤齿比较粗糙,与典型的Pygodus anserinus稍有不同,且在牙形刺十分丰富的样品中仅有一枚此种之Pa分子,所以本文尚有疑问地把这层砾状灰岩归入Pygodus anserinus带,同时不能排除把它归入Pygodus serra带顶部Yangtzeplacognathus protoramosus亚带的可能。由于此剖面牙形刺化石与丰富的笔石共生,为牙形刺带与笔石带的精确对比提供了直接证据。Histiodella动物群在此剖面的发现,不仅具有十分重要的地层意义,而且具有明显的岩相古地理意义。本文详细描述了新种Histiodella wuhaiensis并讨论了Histiodella属5个种之区别。     

海南岛早志留世晚期腕足类Xinanospirifer的发现--兼论南好组

海南岛保亭县毛感乡南兵至南好公路边南好组以往被确认为下石炭统岩关阶 ,并认为与其下的上志留统足赛岭组呈角度不整合接触。著者最近在该剖面南好组中发现兰多维列世特里奇期晚期 (LateTelychian)Xi nanospirifer腕足动物群和三叶虫Latiproetuscf.latilimbatus,证明久归于下石炭统岩关阶南好组的地质时代应改归于早志留世 (Llandoverian) ;海南岛地区在早志留世明显属于扬子地台区的范畴 ;从地质时间上还暗示南好组与其下伏的足赛岭组不可能存在角度不整合接触 ;     

A proposed new global stratotype for Aeronian Stage of the Silurian System: Hlásná Třebaň section,Czech Republic

The current Global Stratotype Section and Point (GSSP ) for the Aeronian Stage (Llandovery Series, Silurian System), on Trefawr track in the Llandovery area of Wales, is an inadequate marker for precise, global, correlation. The International Subcommission on Silurian Stratigraphy has, therefore, undertaken the selection of a new GSSP for this level. The lowest occurrence of the graptolite Demirastrites triangulatus , 1.38 m above the base of the black‐shale succession of the ?elkovice Formation at the Hlásná T?ebaň section in Central Bohemia, is proposed to mark the base of the Aeronian Stage. The section, which fulfils all formal requirements for stratotype of a chronostratigraphical unit, should be considered as a candidate for the new GSSP . An abundant, well‐preserved, diverse graptolite fauna occurs through the section along with common chitinozoans, which indicate that the Spinachitina maennili Biozone spans the boundary interval. The section comprises the lower–middle Aeronian (D. triangulatus–Lituigraptus convolutus graptolite biozones) along with underlying Rhuddanian (Akidograptus ascensus–Coronograptus cyphus biozones) and Hirnantian strata. Several graptolite genera of primary importance in global correlation (Demirastrites , Petalolithus , Rastrites and Campograptus ) first appear in the lower part of the triangulatus Biozone. The structurally simple section is somewhat condensed, but there is a uniform succession of black shale without any evidence of disconformity in the broad boundary interval. The C_org isotope record exhibits a minor positive excursion just above the base of the triangulatus Biozone, whereas TOC and N isotope and elemental geochemical records provide evidence for uninterrupted sedimentation under stable, anoxic conditions.     

江苏泗洪北部两个晚新生代的地层剖面及所含脊椎动物化石

本文描述了泗洪北部两个晚新生代的地层剖面及其所含脊椎动物,确立了泗洪北部广泛分布的砂砾层的层序和时代.含 "Diceratherium" cf. minus 的重岗山的砂砾层的时代为晚中新世早期,含有 Proboscidipparion、Stegodon orientalis 和 Palaeoloxodon naumanni 等化石的归仁砂砾层的时代则为早更新世.     

The Ordovician-Silurian boundary: new data, new concerns

Despite International Union of the Geological Sciences (IUGS) ratification of the International Commission on Stratigraphy recommendation that the base of the Parakidograptus acuminatus zone be the base of the Silurian and that the boundary stratotype be at Dob's Linn, Scotland, numerous concerns continue to be expressed over the timing of the selection as well as the boundary and its stratotype. The richness of both graptolite and non-graptolite biostratigraphic data in numerous stratigraphic sections from many areas in China published at about the same time that the boundary and stratotype were approved formally and shortly after approval suggest the possibility that boundary designation may have been somewhat premature. The new data from China document clearly the major extinction of characteristic Late Ordovician taxa significantly below the presently accepted System boundary. The new data indicate that the re-radiation of graptolites after the extinction took place in the Glyptograptus persculptus zone, the graptolite zone subjacent to the P. acuminatus zone. New geochemical data from Dob's Linn reveal a change in chemistry in strata subjacent to the base of the G. persculptus zone that could be used as an aid in correlation. The new data suggest the possibility that the base of the G. persculptus zone, the relatively traditional base of the Silurian, could be as appropriate a System boundary as the base of the P. acuminatus zone.     

湖南益阳早、中奥陶世的叶笔石属(Phyllograptus)

报道湖南益阳早、中奥陶世的叶笔石1属5种,包括Phyllograptus anna Hall,1865,Phyllograptus anna longus Ruedemann,1947,Phyllograptus anna ultimus Ruedemann,1904,Phyllograptus claviger Monsen,1937,Phyllograptus claviger acuminatus(Chen and Xia),1979。研究表明,该属主要产出于弗洛晚期至大坪中期,在早、中奥陶世笔石多样性演变事件第一阶段的后期(Corymbograptus deflexus带),叶笔石所代表的上攀伸展类型就已萌芽,且在第二阶段(Pseudophyllograptus angustifolius elongatus带-Isograptus victoriae divergens带)于均分笔石动物群中占据优势地位,对该动物群内部类群的演替起着承前启后的作用,同时也验证了笔石动物群自身的演替对于其多样性演变具有重要影响。