PATTERNS OF EVOLUTION AND EXTINCTION IN THE LAST HARPETID TRILOBITES DURING THE LATE DEVONIAN (FRASNIAN)

Abstract: Late Devonian (Frasnian) harpetid trilobites have hitherto only been described from the western side of the Protethys Ocean, in what is now Europe and North Africa, as well as from Gondwana‐derived northwestern Kazakhstan (Mugodjar). However, late Frasnian strata in the Canning Basin, Western Australia, that were deposited on the eastern side of this ocean, contain a rich harpetid fauna. Described herein are two new harpetids: Eskoharpes gen. nov. and Globoharpes gen. nov., within which are placed six species: E. palanasus sp. nov., E. wandjina sp. nov., E. boltoni sp. nov., E. guthae sp. nov., G. teicherti sp. nov. and G. friendi sp. nov. The ontogenetic development of E. palanasus, E. wandjina and G. teicherti are described, including the first unequivocal harpetid protaspis. Globoharpes exhibits evidence of sexual dimorphism in the development of a pronounced preglabellar boss in some specimens. This structure is thought to have functioned as a brood pouch. Such structures have previously only been described in Cambrian and Ordovician trilobites, and never before in harpetids. It is suggested that the characteristic harpetid fringe functioned as a secondary respiratory structure. The Eskoharpes lineage shows evolutionary trends that mirror changes seen in ontogenetic development of the youngest species, suggesting the operation of peramorphic processes. This is the first record of heterochrony in harpetids and the first documented example of peramorphosis in Devonian trilobites. These harpetids demonstrate a stepped pattern of extinction during the late Frasnian, probably related to the effects of the two Kellwasser biocrises that have been well documented in European Frasnian sections. Highly vaulted species of Eskoharpes and the strongly vaulted Globoharpes became extinct at the Lower Kellwasser Event. The flatter species of Eskoharpes became extinct at the base of the Upper Kellwasser Event shortly prior to the Frasnian/Famennian boundary. The extinction of these harpetids, along with contemporaneous forms from Europe, which are also discussed herein, marks the end of the trilobite order Harpetida worldwide.     

新疆巴里坤三塘湖志留纪三叶虫

新疆巴里坤三塘湖晚志留世阿苏山组三叶虫包括Ananaspis fecunda Barrande,Cheirurus barkolensis sp.nov.和Pacificurus sp.,与准噶尔盆地西北部乌图布拉格,哈萨克斯坦及捷克波西米亚的晚志留世三叶虫关系密切。另外对中国5个地区晚志留世三叶虫地层作了对比。Ananaspis,Pacificurus二属在中国是初次发现。     

湖南的一些泥盆纪竹节石

描述湖南中部中、上泥盆统的薄壳竹节石8属27种(或亚种),其中4新种,将它们划分为3个类群:中泥盆统类群以 Nowakia, Viriatellina和Costulatostyliolina 为主,弗拉斯阶下部类群为Homoctenus tenuicinctus tenuicinctus组合,弗拉斯阶上部类群为H.ultimus ultimus组合.     

THE EURYPTERID ADELOPHTHALMUS SIEVERTSI (CHELICERATA: EURYPTERIDA) FROM THE LOWER DEVONIAN (EMSIAN) KLERF FORMATION OF WILLWERATH, GERMANY

Abstract: The eurypterid Rhenopterus sievertsi Størmer from the Lower Devonian of Germany is redescribed. Based on new morphological data, including the possession of prosomal limbs of Adelophthalmus‐type and spatulae on the genital operculum, the species is transferred to Adelophthalmus Jordan, in Jordan and von Meyer and thus is the oldest representative of this geographically and stratigraphically widespread genus. Eurypterus? trapezoides Størmer is recognized as a junior synonym of A. sievertsi.     

广西早泥盆世一新型胴甲鱼化石并初步探讨其系统分类位置

本文描述的胴甲鱼化石标本,采自广西象州大乐早泥盆世地层.化石系内、外模,但保存非常完整,包括自然连接的头部、躯干、胸鳍及躯甲后的尾部.头甲、躯甲的特征较为接近星鳞鱼 (Asterolepis) 的特征,而某些特征又与云南鱼 (Yunnanolepis) 类似.胸鳍分为近节和远节,鳍片排列近似欧洲的翼甲鱼 (Pterichthyodes) 型的胸鳍.根据头甲、躯甲及胸鳍的特征,笔者建立了一新属、新种——Liujiangolepis suni gen. et sp. nov.,代表胴甲鱼类中—新科——Liujiangolepidae fam. nov..文中对新属种的胸鳍结构和新属种在胴甲鱼类中的分类位置做了初步探讨.     

中国泥盆纪珊瑚的生物地理及其群落生态

中国泥盆纪可识别出６个珊瑚生物地理区：南天山区、古特提斯区、华南区、华北北缘区、准噶尔－兴安区和保山区。其中,前４４个区均处于当时赤道两侧的低纬度地区,属于老世界大区;而后２个区则可能分别位于北温带和南温带区域内,不在老世界大区范围内。中国泥盆纪珊瑚群大多数都是生活在温暖浅海近南栅上富氧透光带中的群落,其分异度,丰度和密度各有不同,大致属于海浪底栖生物组合ＢＡ３－ＢＡ４;但也有的生活在远岸大陆斜坡     

记利沃鱼(Livosteus)—新种

详细记述了发现于云南武定早泥盆世晚期利沃鱼(Livosteus)的新材料.依据其特征,建立一个新种.这是该属除在拉脱维亚以外在世界上的第二个种,因此具有重要的古生物地理意义.     

南天山西部泥盆纪Zdimir腕足动物群的发现

新疆乌恰县西部斯木哈纳边境口岸北侧边境线附近含Zdimir腕足动物群的中厚层灰黑色生物碎屑灰岩一直被视为中泥盆统托格买提组。作为一个岩石地层单位,托格买提组的含义应该是分布在托格买提东一带及阿赖山东部以片岩、千枚岩、石英砂岩或以厚层灰岩为主、含腕足动物Stringocephalus,Bornhardtina和珊瑚Temnophyllum,Neospongophyllum等化石群的地层,主体时代为Givetian期。斯木哈纳边境口岸北侧边境线附近中厚层灰黑色生物碎屑灰岩与托格买提组的岩性差异较大,应另建新组名。对Zdimir动物群详细研究后证实,这套地层的时代大致为早泥盆世晚期(Emsian期)。     

湖南晚泥盆世短胸节甲鱼类一新属

本报道的鱼类化石产自湖南石门大京州的上泥盆统写经寺组。在中国泥盆纪地层分区上,化石产地属于华南区的湘、鄂、川交界分区(侯鸿飞等,1988)。该分区泥盆系为一套厚度不超过500m的近岸海相碎屑岩沉积,仅发育中泥盆统上部至上泥盆统(图1),并普遍超覆在志留系温洛克统之上,以角度不整合伏于石炭系或二叠系之下。上泥盆统分两个组,从下而上分别为黄家磴组和写经寺组。黄家磴组系杨敬之、穆恩之(1953)创立,标准地点在湖北长阳马鞍山东端的黄家磴。岩性为砂岩夹少量页岩,植物化石丰富,并含有误订为植物化石的湖北长阳鱼(Changyanophyton hupeiense Sze,1952)。根据植物化石组合面貌,黄家磴组的时代被认为是晚泥盆世早期。写经寺组是谢家荣、刘季辰(1927)创立的。岩性分为二段：下段以泥灰岩为主,含Yunnanella abrupta、Yunnanellina triplicata等腕足类化石;上段以砂页岩为主,含植物化石,其组合面貌除大致与黄家磴组相似外,还有一些新的分子,如Leptophloeum guanzhuangense、Cyclostigma hunanense等。根据动、植物化石群的性质,写经寺组的时代大致与法门期早期相当。多年来,在这一分区的泥盆纪地层里,很少鱼类化石。杨敬之、穆恩之(1953)曾提及在湖北长阳写经寺组底部发现的鱼化石,这些鱼化石与腕足类Yunnanella、Tenticospirifer等共生,但种属并未定出。已记述过的鱼化石只有湖北长阳黄家磴组的长阳鱼(潘江,1962)。     

广西象州中泥盆世晚期的海星

在广西象州中泥盆统东岗岭组壳相含泥质石灰岩中发现一个海星口面化石 ,定名为Devonasterguangxiensissp .nov .。该种中盘较大 ,腕长且直 ,下缘板发育 ,口角板肥大 ,略尖 ,与美国标本Devonastereucharis(Hall)相比 ,有一定的区别。海星化石与东岗岭组常见化石Actinopteria(双壳类 )和Atrypa(腕足类 )     

贵州早泥盆世刺镰蕨的新观察

刺镰蕨在早泥盆世是一种广布于世界的植物,尽管报道自许多地点,但远未完全地了解它,其主要原因是能育材料罕见。我们观察的标本采自贵州早泥盆世的丹林组。它显示具柄的孢子囊侧生于靠近叶腋的轴上,我们的标本近似球形的孢子囊和它的形态略小于雷诺的肾形孢子囊外,其它方面如：带状的营养轴上具有疏螺旋排列的镰刀状叶,具短柄的孢子囊侧生于轴上以及管胞具穿孔壁等性状与雷诺修订后的刺镰蕨完全一致。我们同意雷诺的观点,将镰蕨目升为纲,与工蕨纲和石松纲并列。它的系统位置是介于工蕨纲和石松纲之间。其下包含一目、一科三个属——镰蕨属、巴拉格瓦纳彻属和星木属。这种植物的生殖部分在中国尚属首次报道。     

塔里木盆地北部晚泥盆世孢子组合

塔里木盆地北部草２井东河塘组产丰富的、保存完好的孢子化石,计３７属７３种,据此建立Ａｐｉｃｕｌｉｒｅ－ｔｕｓｉｓｐｏｒａ ｈｕｎａｎｅｎｓｉｓ－Ａｎｃｙｒｏｓｐｏｒａ ｆｕｒｃｕｌａ（ＨＦ）孢子组合带。对一些孢子的已知地质分布记录及其与西欧和塔西南晚泥盆世孢子组合带序列的对比讨论,表明ＨＦ孢子带的时代为晚泥盆世法门期,大致与爱尔兰晚泥盆世ＬＬ＋ＬＥ孢子带时代相当。描述孢子３新种,图示孢子６１种。     

A HEXAPOD FROM THE EARLY DEVONIAN WINDYFIELD CHERT, RHYNIE, SCOTLAND

Abstract: New diagnostic morphological features discovered following a re‐examination and further preparation of the holotype of Leverhulmia mariae Anderson and Trewin from the Early Devonian (Pragian) Windyfield chert are described and discussed here. The discovery of anterior (thoracic?) leg appendages with attached pretarsal elements comprising a fixed median unguis, a pair of articulated lateral ungues and possible unguitractor plate has allowed us to reclassify this enigmatic fossil as Hexapoda incertae sedis. We interpret the holotype as part of an abdomen bearing at least five pairs of segmented leglets. The condition of the ungues on the anterior appendages is strongly reminiscent of Archaeognatha and Zygentoma (= Thysanura s.s.), and the segmented leglets on the abdomen show similarities with certain fossil ‘apterygotes’ known from the Carboniferous. Leverhulmia is the third hexapod species found in the cherts at Rhynie, the other forms being the collembolan Rhyniella praecursor Hirst and Maulik, and the pterygote insect Rhyniognatha hirsti Tillyard. Showing closer affinities with Archaeognatha and Zygentoma, Leverhulmia may well represent the earliest fossil apterous insect known to date.     

桂林上泥盆统的串管海绵

串管海绵的Amblysiphonella属在桂林地区融县组的发现,填补该属在晚泥盆世地质历程中的空白。在此之前,国内、外已出版地质文献中未记载该属在泥盆系发现的种。     

A NEW DIPNOAN FISH FROM THE MIDDLE DEVONIAN (EIFELIAN) OF SCOTLAND

Abstract:  A new dipnoan fish, Pinnalongus saxoni gen. et sp. nov., is described from a suite of recently discovered specimens from Caithness and East Sutherland, northern Scotland. The stratum where Pinnalongus occurs is within the middle Eifelian of the Middle Devonian. Pinnalongus has a skull roof consisting of a mosaic of small bones at the anterior end, a feature more typically found in Early Devonian dipnoans. The posterior part of the skull roof is more typical of later advanced Middle Devonian dipnoans with the B-bone separating the I-bones. The postcranial body is now considered not to be so important with respect to the classification of dipnoans as originally proposed by Dollo in 1895, who thought there was an evolutionary transformation series. Nevertheless, the postcranial body of Pinnalongus has more in common with later Middle and Late Devonian dipnoans such as Scaumenacia , with a very long second dorsal fin. Based on the skull morphology, Pinnalongus is most closely related to Tarachomylax from the Lower Devonian of Severnaya Zemlya, Russia. Pinnalongus represents the earliest known complete articulated dipnoan with tooth plates.     

湖南湘乡上泥盆统佘田桥组介形类

本文首次报道了湖南湘乡上泥盆统佘田桥组介形类化石,共有１８属３５种及未定种,其中包括１１新种。通过与国内外泥盆纪和早石炭世介形类进行比较表明,它们与下伏的中泥盆统棋梓桥组介形类组合和上覆的上泥盆统锡矿山组介形类组合均有明显的差别,该介形类动物群的发现,为佘田桥组的地质时代的确定及地层的划分对比提供了新的古生物依据,并对研究介形类动物群的演化增加了新的资料。     

EARLY VERTEBRATE FOSSILS FROM THE EARLY DEVONIAN OF ZHAOTONG DISTRICT, NORTHEASTERN YUNNAN

Astothegaleaspids,thePosongchongFormationofZhaotongDistrictismostsimilartothePingyipoFormationofJiangyou,Sichuan.BothLungmenshanaspisandSanqiaspisareexclusivelyfoundinthesetworegions,indicatingthepresenceofbiogeographicconnection.PaleontologicStudiesSubclassGaleaspidaTarlo,1967orderHuananaspiformesJanvier,l975FamiIySanqiaspididaeLiu,l975GenusSanqiasPisLiu,l975TyPespeciesSanqiasPisrostrataLiul975.ReferredspeciesSanqiasPiszhaotongensisLiul97iEmendeddiagnosisCephalicshieldnarrow,rou…     

新疆南天山早泥盆世阿尔皮什麦布拉克组床板型珊瑚群及其生物地理意义

对床板珊瑚化石群的分析表明,南天山阿尔皮什表布拉克组的地质时代为早泥盆世早期,所含珊瑚群与滇西北,西秦岭,内蒙古达尔罕茂明安联合旗,吉林二道沟的珊瑚群面貌相似,明确属于古特提斯生物地理区内,而与北天山,淮噶尔,北山,大,小兴安岭等地区同期地层所产者存在明显差异。