娇笔石科的新材料

最近笔者等整理浙江的笔石标本时,发现一些娇笔石科的笔石,这些笔石经鉴定有下列四种:1.中国双线笔石Dinemagraptus sinicus Mu et Qiao(新种)2.美丽娇笔石Abr(?)graptus f(?)rmosus Mu3.三枝拟娇笔石Parabrograptus tribrachiatus Mu et Qiao(新属、新种)4.分枝江山笔石Jiangshanites ramosus Mu et Qiao(新属、新种)这些笔石标本大部分是卢衍豪、穆恩之、侯祐堂、张日东、刘第墉等在浙江江山黄泥岗附近的中奥陶统胡乐页岩组中所采得的;小部分是葛梅钰、景延祥、张德明等在浙江龙游志棠附近的胡乐页岩组中采得的。娇笔石科系笔者之一(穆恩之)于1958年创立的。这一科的特征是,两枝的无轴笔石,除了胎管以外,其体壁均已退化,形成网线结构。在创立该科时包括两个属,即双     

湖北宜昌早志留世笔石

本文着重研究湖北宜昌早志留世笔石的新材料,共描述18属50种,其中有一个新属和一个新亚属,34新种和新亚种,从而对本地区的志留系划分提供了依据,并对早志留世笔石带作了补充。在研究花瓣笔石(Petalolithus)特征和轴囊构造的基础上,认为Petalolithusmirabilis Mu et al.应独立成属,定名为分裂笔石(新属)(Dischidograptus gen.nov.)。根据笔石体胞管口部特征,在耙笔石属(Rastrites)中,建立一新亚属,取名为喇叭笔石(新亚属)Rastrites(Lituigraptus)subgen.nov.。     

贵州遵义高桥奥陶系湄潭组下部的笔石

对贵州遵义高桥大角寺剖面的奥陶系湄潭组下段和中段笔石的研究结果表明,湄潭组下段从下而上可以识别出Didymograptellus eobifidus带、Corymbograptellus deflexus带和Azygograptus suecicus带;中段含有一层笔石,缺少特征属种,根据其总体面貌,可能相当于Expansograptus hirundo带。文章描述其中11属16种:Pseudophyllograptus angustifolius(Hall),Phyllograptus claviger(Monsen),P.annaHall,Didymograptelluseobifidus(Chen and Xia),D.protoindentus(Monsen),Acrograptus kurcki(T rnquist),Corymbograptus vacil-lans(Tullberg,1880),C.deflexus(Elles and Wood),Expansograptus extensus(Hall),E.nitidus(Hall),Xi-phograptus lofuensis(Lee),X.cf.lofuensis(Lee),Azygograptus suecicusMoberg,Dictyonemasp.,Den-drograptussp.,Inocaulis plumulosusHall。这一笔石动物群分异度较低,大多数为上扬子区的常见属种,代表当时黔中古陆北缘近岸海洋环境中的笔石动物群面貌。     

辽宁太子河流域上寒武统树形笔石

1979年秋,笔者作为华北地层队成员和其他同志一起,在辽宁辽阳五顶山和本溪田师付腰堡附近,上寒武统凤山组燕州层,采得不少Dictyonema wutingshanense Mu和其它属、种的笔石。这个笔石群都是上寒武统凤山组Dictyonema wutingshanense带的分子。Dictyonema wutingshanense系穆恩之于1953年创名,产地为辽宁辽阳五顶山上寒武统凤山组,和三叶虫Quadraticephalus共生,根据穆的意见,此一笔石带包括在三叶虫Quadraticephalus带中。     

断笔石科的新材料及其意义

1982年冬,建字734单位在湘西苗族自治州首府吉首城北1.5km(上岩寨东南550m)处的下奥陶统桥亭子组灰绿色板岩内采得一些笔石,经笔者鉴定,其中建立一新属——吉首笔石属(Jishougraptus gen. nov. ),共生的有 Didymograptus of. praenutius T?rnquist,其时代应属早奥陶世,相当 Didymograptus hirundo 带.这一新的笔石属为一单枝、单列的笔石.有意思的是,这种笔石的笔石体形状、始芽发育等特点和断笔石,尤其和起伏断笔石(Azygo-     

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。     

川西汉源-荥经地区下奥陶统大乘寺组的笔石

对川西汉源-荥经地区CYD2井下奥陶统弗洛阶大乘寺组的笔石进行研究,结果表明Baltograptus deflexus笔石带在这一覆盖区发育良好。CYD2井的该带笔石动物群共含2属5种。根据下垂对笔石类的始端发育型式,修正前人对波罗的笔石属(Baltograptus)和巅峰笔石属(Corymbograptus)内一些种的归属,并对CYD2井的5种笔石进行描述。可能受制于钻心标本的限制,该地区的Baltograptus deflexus带笔石动物群分异度较低。川西汉源-荥经-峨眉山地区的大乘寺组与上覆二叠系梁山组呈假整合接触,表明该地区长期遭受沉积间断和剥蚀作用,B.deflexus带的确定,指示了这一长期剥蚀作用的最大深度。     

桂北兴安早奥陶世的Exigraptus和Glyptograptus并论双列有轴笔石的起源

早奥陶世宁国期中期(阿伦尼克晚期)的雕笔石,是最早出现的双列有轴笔石.由于牵涉到双列有轴笔石的起源,历来为各国笔石研究家们所注目.以前,产于我国浙西的Glyptograptus sinodentatus Mu et Lee被认为是最早出现的双列有轴笔石(穆恩之、李积金,1958),当时穆、李提出这类雕笔石的祖先"可能是一个和Cardiograptus相似之物".最近,穆恩之等     

湖南早奥陶世弗洛期的笔石新属——挪威笔石属(Norvegiograptus gen.nov.)

报道产自湖南益阳南坝剖面下奥陶统弗洛阶的笔石新属——挪威笔石属(Norvegiograptus gen.nov.),该属归属于均分笔石科(Dichograptidae)对笔石亚科(Didymograptinae),主要特征是第一个胞管(th11)自胎管中部生出,始端发育型式为artus型,笔石体两枝纤细、下斜至下曲伸展。属内包含两个种:Norvegiograptus liber(Monsen)和Norvegiograptus enshiensis(Ni)。     

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.     

Restudy of some Ordovician–Silurian boundary graptolites from Anticosti Island, Canada, and their biostratigraphic significance

The Ellis Bay Formation on Anticosti Island has long been recognized for the biostratigraphic importance of its latest Ordovician conodont, palynomorph, and shelly fossil assemblages. However, a sparse record of graptolites has made it difficult to correlate these assemblages with the graptolite biozonation. Restudy of some previously described and examination of newly collected normalograptid specimens from the Ellis Bay and lower Becscie formations, however, shows that biostratigraphically important taxa are present and these species provide important constraints on the age of the strata. Normalograptus parvulus and N. minor have been identified in the upper half of the Ellis Bay Formation, suggesting that these strata are late Hirnantian in age ( N. persculptus Biozone). Normalograptus imperfectus and Normalograptus sp. aff. N. acceptus occur in the basal beds of the Becscie Formation, indicating that these strata are earliest Silurian. These graptolite data support the hypothesis that the positive carbon isotope excursion seen in the uppermost strata of the Ellis Bay Formation is isochronous with that seen in the Hirnantian strata at Dob's Linn, Scotland, and does not span much of the lower to mid-Hirnantian, as is the case in Arctic Canada and Nevada, USA.     Anticosti Island , Hirnantian, graptolites, Ordovician, Silurian.     

A relict Ordovician brachiopod fauna from the Parakidograptus acuminatus Biozone (lower Silurian) of the English Lake District

At Yewdale Beck in northern England, a brachiopod fauna dominated by species of Hindella, Kinnella, Mirorthis, Paromalomena and Plectothyrella , occurs interbedded with a graptolite fauna which includes Akidograptus ascensus , Atavograptus ceryx , Persculptograptus parvulus and Normalograptus spp. (including probable examples of N. normalis , N. angustus and N. medius ) within the lower part of the Skelgill Formation. This suggests that taxa of the terminal Ordovician Hirnantia fauna occur within the lower P. acuminatus Biozone, representing the youngest documented occurrence of the Hirnantia brachiopod fauna. Biostratigraphy, brachiopods, graptolites, Ordovician-Silurian boundary.     

HIRNANTIAN (LATEST ORDOVICIAN) GRAPTOLITES FROM THE UPPER YANGTZE REGION, CHINA

Abstract:  The Upper Yangtze region yields a Hirnantian (latest Ordovician) graptolite fauna that includes 41 species assigned to 13 genera. This fauna is particularly important for understanding the Late Ordovician mass extinction event because it is the most diverse known from this interval. In addition, it records the survival, well into the Hirnantian, of many taxa of the Dicranograptidae-Diplograptidae-Orthograptidae (DDO) fauna, which was previously regarded as having gone extinct at the beginning of the Hirnantian. Taxa exhibiting six different astogenetic patterns, including taxa with reclined stipes, scandent, biserial, full-periderm and 'archiretiolitid' rhabdosome forms occur in the lower Normalograptus extraordinarius-N. ojsuensis Biozone. In contrast, in the upper N. persculptus Biozone only four genera remain, all but one of which are Normalograptidae: scandent and biserial taxa with Pattern H astogeny. Normalograptids are the dominant form of the succeeding, lower Rhuddanian, faunas. The Yangtze faunas also document the early expansion of normalograptids coeval with the decline of the DDO fauna. Many previously identified species considered endemic to China have been synonymized; 24 of the 41 species recorded here have been recognized elsewhere. No new taxa are described.     

扬子北缘钟祥地区奥陶系弗洛阶笔石动物群研究

湖北钟祥下奥陶统弗洛阶岩性以灰黑色页岩为主,夹粉砂岩及灰岩透镜体, 化石丰度和分异度高。通过系统的化石采集和鉴定, 于钟祥温峡口剖面识别出笔石7属31种, 大体上为扬子地台区的常见属种。自下而上分为Didymograptellus bifidus带、Corymbograptus deflexus带和Azygograptus suecicus带。该序列与宜昌?南漳地区一致, 但在笔石动物群组成面貌上差异较大,可能与钟祥地区在早奥陶世位于扬子台地边缘, 富集的营养物质和低氧的环境更利于笔石动物群的繁盛和笔石化石的保存有关。     

An Unusually Diverse Llandovery (Silurian) Diplograptid Fauna from the Southern Urals of Russia and Its Evolutionary Significance

This vesiculosus Biozone assemblage of chemically-isolated graptolites from the Orenburg District of Russia was obtained from limestones associated with pillow lavas of the Sakmara Formation of Silurian–Early Devonian age. It comprises 30 species, of which 24 are described. Nine are new, one is a new subspecies, and eight are left under open nomenclature. The assemblage is unique in its diversity of minute biserial graptolites referable to the genera ' Glyptograptus ', Normalograptus , Sudburigraptus , and Metaclimacograptus ; and is unusual in that well-preserved graptolite faunas are rare at this stratigraphical level, which is fixed by the occurrence of Cystograptus vesiculosus (Nicholson) s.l. and Paraclimacograptus innotatus (Nicholson). The following new forms are described: ' Glyptograptus ' tamariscus praecursor subsp. nov., G. mazovoensis sp. nov., G. nikitini sp. nov., G. pavlinovi sp. nov., G. telarius sp. nov., G. zimai sp. nov., Normalograptus legrandi sp. nov., N. melchini sp. nov., N. sobolevskayae sp. nov., and Metaclimacograptus bjerreskovae sp. nov. Five evolutionary lineages are defined within the ' Glyptograptus ' tamariscus (Nicholson) plexus, modifying and extending the pioneer work of Packham (1962). The diverse ' Glyptograptus ' faunas are considered to be a replacement for the Normalograptus fauna which peaked in the late Ordovician and early Silurian. Metaclimacograptus , although reasonably diverse in its speciation, exhibits a conservative style of evolution with little fundamental change throughout the Llandovery. It is suggested that cortical bandages have species-specific dimensions and micro-features. Some problematical micro- and ultrastructural features are described, notably fibrillar textures, parallel to the fusellar margins, in several species.     

Latest Ordovician graptolites from the Mandalay Region,Myanmar

The graptolite fauna of the Mandalay Region, Myanmar, is poorly known. In this paper, 13 species in the genera Avitograptus, Korenograptus, Metabolograptus, Neodiplograptus and Normalograptus are described from the uppermost Ordovician strata of the area. Two of these species, Korenograptus selectus X. Chen n. sp. and Neodiplograptus mandalayensis X. Chen n. sp., are new. On the basis of the graptolite faunas, a biostratigraphic scheme for the uppermost Ordovician (Hirnantian: Metabolograptus extraordinarius Biozone and Metabolograptus? persculptus Biozone?) strata in this area is erected.     

ISOLATED GRAPTOLITES FROM THE LITUIGRAPTUS CONVOLUTUS BIOZONE (SILURIAN, LLANDOVERY) OF DALARNA, SWEDEN

Abstract:  Isolated material of 13 graptolite species from the Aeronian (middle Llandovery) Lituigraptus convolutus Biozone is described. A considerable amount of late astogenetic peridermal thickening is revealed in Normalograptus scalaris and Rivagraptus bellulus . As a result, in the former, thecal morphology is modified from climacograptid to pseudoglyptograptid; in both species, the virgella becomes robust. In Metaclimacograptus minimus and Me. sp., it is shown that the dorsal metathecal wall forms the genicular hood, whereas in N. nikolayevi , the infragenicular wall of the succeeding theca forms the distal thecal apertural margin. Pribylograptus argutus exhibits typical pribylograptid thecae along the length of the available rhabdosome fragments. Characters differentiating Campograptus lobiferus from C. harpago include the greater dorso-ventral width and more rapid increase in dorso-ventral width of the former and the greater recurving of distal thecae and presence of thecal spines/processes on all thecae of the latter. Lituigraptus convolutus has rastritiform thecae proximally; thecal apertures throughout the rhabdosome are crescentic and laterally expanded.     

Integrated Silurian Chitinozoan and Graptolite Biostratigraphy of the Banwy River Section, Wales

The succession of 38 upper Llandovery–lower Wenlock chitinozoan taxa from graptolitic horizons in the Banwy River section (Powys, Wales) is described. Five new species are named: Bursachitina nestorae Conochitina leviscapulae Conochitina mathrafalensis Belonechitina cavei Belonechitina meifodensis . A further ten taxa are described under open nomenclature. Seven chitinozoan biozones are recognized in the Banwy River section, three of which ( Cingulochitina bouniensis Conochitina acuminata Salopochitina bella ) are new. The base of each biozone is correlated with the graptolite biostratigraphical scheme as follows: Angochitina longicollis Biozone — upper spiralis Biozone; Conochitina acuminata Biozone — lowermost lapworthi Biozone; Margachitina banwyensis Biozone — upper lapworthi Biozone; Margachitina margaritana Biozone — lowermost insectus Biozone; Cingulochitina bouniensis Biozone — upper murchisoni Biozone; Salopochitina bella Biozone — upper firmus Biozone. The succession of chitinozoan biozones in the Banwy River section is compared with that in other sections which have graptolite biostratigraphical control. This has highlighted the following: (1) the correlation of the base of the dolioliformis Biozone with the graptolite biozonation is imprecise; (2) E. dolioliformis is recorded only from levels after the first A. longicollis in Sweden (although this may reflect previously unrecognized synonymies); (3) the longicollis Biozone may be diachronous, its base correlating with levels low in the Telychian in Sweden, Norway and Estonia and with the upper Telychian spiralis Biozone in Wales and the Prague Basin; (4) data herein and from the Prague Basin indicate that the base of the margaritana Biozone correlates with a level low in the insectus Biozone.