Crinoid localities of the Devonian of the British Isles

Who collects the Devonian crinoids of south-west England? Since the nineteenth century, almost nobody. Few palaeontologists pursue these fossils, undoubtedly handsome in life, but indifferently preserved. Herein, we make a survey of four of the most important crinoid sites, all of which have the potential to produce new specimens.     

New Devonian plant fossil occurrences on the New South Wales South Coast: geological implications

Devonian fossil localities are summarised for coastal southeastern Australia, including both marine invertebrates representing a major late Frasnian (Late Devonian) transgression, and plant remains of Middle–Late Devonian age in associated non-marine strata. Lycopsid plant specimens (Leptophloeum) from near Majors Creek, NSW, first documented by Edgeworth David and E. F. Pittman in association with marine fossils to demonstrate a Late Devonian age, are illustrated for the first time. Lycopsid plants of presumed Middle Devonian age are illustrated from three new localities: Yowrie River inland from Cape Dromedary, Tuross River northwest of Narooma and Charlies Forest Road northeast of Braidwood. The Yowrie River occurrence (in float) indicates probable Middle Devonian strata upstream that are not shown on published maps. The Tuross River occurrence is in sheared and folded strata previously mapped as Ordovician, and the Braidwood occurrence demonstrates Devonian black shales adjacent to previously mapped Ordovician. Evidence supporting alternative thrust or simple fold interpretations for the Budawang Synclinorium is discussed, and relevant Ordovician fossil localities are listed.     

甘肃省重要古植物化石产地区划及保护利用

古植物化石是地质历史时期各类植物实体或遗迹的残留.对古植物化石产地进行系统的调查和区划研究是开展古生物化石保护和利用工作的基础.在资料研究和实地调查的基础上,对甘肃省24处重要古植物化石产地进行了评价和区划研究.甘肃省古植物化石产地可划分为北山地区、祁连山——河西走廊地区、鄂尔多斯和秦岭地区4个古生物化石大区以及6个古...     

中国现代人类起源:来自南方化石地点的年代学证据

现代人类起源的时间和地点是当前古人类学研究和争议的热点。文中评述了 2 0多年来第四纪测年技术取得的进展及其对现代人类起源研究的影响。基于新生碳酸盐岩铀系测年 ,研究了中国南方柳江人洞等多个晚期人类化石地点的年代 ,结果远大于原认为的 2 0～ 30ka。晚期智人在中国出现的时间很可能不晚于西亚和南非 ,中国 4 0～ 1 0 0ka间人类化石的“缺环” ,很可能只是测年技术系统误差造成的假象。上述年代学新证据不支持中国现代人类全部来自非洲的假说。对岩溶洞穴遗址进一步的综合研究 ,有可能为破解有关现代人类起源的诸多疑点提供重要的以至一锤定音的证据     

甘肃省重要古植物化石产地区划及保护利用

古植物化石是地质历史时期各类植物实体或遗迹的残留。对古植物化石产地进行系统的调查和区划研究是开展古生物化石保护和利用工作的基础。在资料研究和实地调查的基础上,对甘肃省24处重要古植物化石产地进行了评价和区划研究。甘肃省古植物化石产地可划分为北山地区、祁连山——河西走廊地区、鄂尔多斯和秦岭地区4个古生物化石大区以及6个古植物化石产地集中区。根据古植物化石产地的科学价值和美学价值,具体从科学性、稀有性、完整性、保存程度、可保护性5个单因素分别对24处重要古植物化石产地进行了评价。在单因素评价基础上进行了综合鉴评,共鉴评出世界级化石产地1处,国家级化石产地7处,省级化石产地16处。根据产地自然区划、行政区划等要素划分了古植物化石产地集中保护区6个。根据保护区内古植物化石产地级别及重要程度,划分出特级保护区2个,重点保护区2个和一般保护区2个。提出对重要古植物化石产地实行化石标本保护加原产地保护的建议。     

陕西北部发现多个新近纪哺乳动物化石新地点及其意义

在陕北黄土高原下部的红土堆积中新发现29个新近纪哺乳动物化石地点,自北向南包括神木、榆阳、佳县、横山、子洲、志丹、安塞、甘泉等地,基本覆盖整个陕北黄土高原,填补了中新世时期中国哺乳动物地理格局中东西分界线附近的大片空白。动物组合以新近纪中国北方常见的三趾马动物群成员为主,包含有三趾马(Hipparion)、大唇犀(Chilotherium)、萨摩麟(Samotherium)、巨鬣狗(Dinocrocuta)、弓颌猪(Chleuastochoerus)、羚羊(Gazella)等,其组合特点类似于府谷老高川中部动物群。新发现的、多地点的化石材料进一步表明,在陕西北部晚中新世约6.7 Ma左右,森林-草原混合型三趾马动物群的分布可能相当广泛,而约7.8 Ma和约5.7 Ma两期的哺乳动物群的分布可能相对局限。

     

中国几个主要哺乳动物地点的晚上新世—早更新世界线

<正> 中国的第三系—第四系界线的讨论和第三系、第四系剖面的研究,历史悠久,发表过不少论文。30多年来的工作大致在几个方面较多:1.黄土沉积剖面;2.河湖相沉积剖面;3.洞穴沉积剖面;4.海相沉积及滨海相平原沉积剖面。在磁性地层学方面研究及划分第四纪下限,有三种不同的划分:1.地层段的下限与奥特威亚时底界一致,大致是190万年;2.以松山/高斯转换的位置,约248万年;3.上限同高斯顶界一致(248万年),下限在300万年左右。     

四川宝兴灵关─金台山飞来峰泥盆纪地层古生物

首次详细地描述了灵关一金台山飞来峰泥盆纪地层剖面，将泥盆系划分为平驿铺组、甘溪组、养马坝组和观雾山组４个岩石地层单位，建立了４个腕足类组合带和２个珊瑚类组合带，并与邻区进行了对比。通过年代地层界线的讨论，初步认为该飞来峰内仅有下泥盆统和中泥盆统中下部地层。     

四川宝兴灵关─金台山飞来峰泥盆纪地层古生物

首次详细地描述了灵关一金台山飞来峰泥盆纪地层剖面，将泥盆系划分为平驿铺组、甘溪组、养马坝组和观雾山组４个岩石地层单位，建立了４个腕足类组合带和２个珊瑚类组合带，并与邻区进行了对比。通过年代地层界线的讨论，初步认为该飞来峰内仅有下泥盆统和中泥盆统中下部地层。     

Hypersaline and anoxia in the Devonian Frasnian-Famennian transition :Molecular fossil and mineralogical evidence from Guangxi ,South China

Abundant normal alkanes, isoprenoid hydrocarbons, terpanes and steranes were detected in 23 samples taken from the carbonate platform to basin facies in the Devonian Frasnian-Famennian (F-F) transition of Guangxi, South China. They were mainly derived from the phytoplankton or bacteria and algae. Molecular stratigraphic parameters, abundant micron gypsums and pyrite framboids show that hypersaline and anoxia prevailed in the F-F transition, the highly stressed environments occurred near the F-F boundary. Orbital cyclostratigraphic studies indicate that the hypersaline and anoxia prevailed in the F-F transition spanned an interval at least from the Palmatolepis linguiformis conodont Zone to the Middle Palmatolepis triangularis conodont Zone and lasted about 1.2 Ma. The Devonian marine ecosystem underwent Early Devonian gradual optimization, Middle Devonian to the F-F transitional stepwise deterioration and late Famennian recovery. A positive feedback among higher surface ocean temperatures, hypersaline, water column anoxia, enhanced nutrient regeneration, phytoplankton productivity and eutrophication was probably substantial in the F-F transition in Guangxi, South China, even in other regions of the world, such as Holy Cross Mountains of Poland, Montagne Noire in southern France, Alberta in Canada. The point that should be emphasized is that the decisive and direct causes of the F-F transitional mass extinction would be the stepwise deterioration of the marine ecosystem since the Middle Devonian other than a bolide impact on the earth. The hypersaline and anoxia prevailed in the F-F transition favor the formation and preservation of hydrocarbon source rocks in South China.     

吉林省泥盆系层序的新划分

<正> 吉林省泥盆系露头比较零星,地层资料也比较少。1966年李东津等在永吉县黄榆屯西王家街发现泥盆纪珊瑚,长春地质学院等命名为王家街组。分布在磐石县呼兰镇至黑石镇一带的变质岩系呼兰群经郭鸿俊的研究被划为志留—泥盆系,但至今仍有争议。笔者通过珊瑚化石的研究,肯定了原定为志留系的二道沟灰岩为早泥盆世早期地层,又在王家     

Devonian volcanics in the New England Orogen: tectonic setting and polarity

The tectonic setting of the Devonian rocks in the New England Orogen has been the subject of considerable debate and controversy for many years. Our studies reveal that they have formed in intra-oceanic island arc and back arc basin (BAB) settings based on Th/Yb, Nb/Yb, Ba/La and Zr/Y ratios. Further, many of the samples that formed in a BAB have a mixture of MORB and arc-like characteristics, a few are almost entirely MORB-like. The arc-like features are believed to be due to the presence of a subduction component in the basaltic magma, the amount of which is controlled by the distance from the arc. Those samples with MORB-like compositions are thought to have originated at spreading centres. The compositions of Late Devonian basalts become more arc-like to the west suggesting a west facing polarity. Based on the tectonic setting and spatial relationship of Late Devonian sequences, we propose that two subduction zones existed during the Late Devonian, one dipping west beneath the Lachlan Orogen, the other dipping east beneath a rifted intra oceanic arc. Obduction of this intra oceanic arc over the continental margin of the Lachlan Orogen in the latest Devonian at approximately 375 Ma led to the development of a new west dipping subduction zone oceanward and commencement of continental, arc magmatism.     

Recent and fossil resins from New Zealand and Australia

The carbon-13 nuclear magnetic resonance spectra of fossil resins from New Zealand and Australia have been compared with those of modern and semifossilized materials. The great majority of the fossilized samples have strong spectral similarities to modern Agathis resins and to North American fossil resins, which have been attributed to Agathis. The Agathis-related spectra are different from those of modern Hymenaea and Araucaria. A small subgroup of Late Cretaceous resins from Australia and Papua New Guinea appears to derive from a different botanical source and shows strong resemblances to Claiborne amber from Arkansas. The spectral resonances of the exomethylene carbons degrade over time and on average provide an approximate measure of the geological age of Agathis-related fossil resins. © 1993 John Wiley & Sons, Inc.     

华东白垩纪暴龙类恐龙蛋化石的新发现

华东地区虽然迄今没有发现可靠的暴龙类恐龙骨骼化石,但近年在浙江天台白垩纪赤城山组地层中发现了白垩纪巨型暴龙类恐龙产的西峡巨型长形蛋（Macroelongatoolithus xixiaensis）化石。因暴龙类恐龙目前在系统分类上被归入兽足亚目（Theropoda）暴龙超科（Tyrannosauroidea）暴龙科（Tyrannosauridae）,建议巨型长形蛋化石也可采用相应分类方法,归入长形蛋化石亚目（Elongatoolithineae）巨型长形蛋化石超科（Macroelongatoolithoidea）巨型长形蛋化石科（Macroelongatoolithidae）,以便对应研究。这些蛋究竟是哪一种暴龙类恐龙所产？从目前掌握资料分析,在东亚的暴龙类恐龙属种中,冠龙和帝龙个体较小,成年体长分别仅约3m和1．6m,年代更早,分别为约160Ma和130Ma,基本上可以排除在外。鹰龙和分支龙成年体长5m～6m,还不能算巨型暴龙类恐龙。只有体长达10m,甚至更大的特暴龙,似乎最有可能产下这样的巨型长形蛋。但特暴龙迄今已知的化石层位时代为晚白垩世末期的Maastrichtian期（71Ma～65Ma）,而浙江的巨型长形蛋的年代则是晚白垩世早期的Turonian期（约92Ma）。这样就存在两种可能,或许是特暴龙的生存年代要上溯到约92Ma,或许这种巨型长形蛋是另一种目前尚不为人知的,生存年代在约92Ma的巨型暴龙类恐龙所产。此外,根据这些蛋化石的外形特征及其在巢穴里的分布方式可以推测,这种暴龙类恐龙,具有功能双输卵管系统,每次产卵2枚,蛋在巢穴里呈2个一组放射状排列。其蛋壳并非刚性的硬壳,而是具有一定韧性的厚牛皮纸状外壳,在重力作用下变形呈扁的长椭球形。     

西准噶尔晚泥盆世新建岩石地层单位:塔克台组

西准噶尔塔克台高原周围一套碎屑岩地层曾被划为下石炭统和布克河组(洪古勒楞组的晚出异名),但其岩性组合、沉积环境与化石面貌均与和布克河组或洪古勒楞组的定义不符,也难以归纳到区域上其他已知地层单元中,故以此建立一个新的岩石地层单位:塔克台组,并分为上、下2段:下段为火山碎屑岩夹火山岩,上段为正常碎屑岩、火山碎屑岩、钙质碎屑岩夹少量灰岩、火山岩和薄煤层.该组与下伏文洛克统沙尔布尔组呈角度不整合接触,上未见顶,多门类动植物化石的发现限定了该组的时代为晚泥盆世,形成于水体逐渐变浅的滨、浅海至沼泽环境.塔克台组与邻区同期的朱鲁木特组、洪古勒楞组为同时异相关系,晚泥盆世研究区海水从西向东侵入并退出是造成这种同时异相关系的主要原因.      

澄江化石库中的双胚层动物新知

作为观察寒武纪大爆发主幕奥秘的最佳科学窗口,澄江化石库展示了三胚层动物(即两侧对称动物)首次全面大辐射的历史产物,让学术界终于看到了已知最古老的同时包括原口类和后口类两大支系的动物谱系庞大“树冠”的主体轮廓,从而给许多较高级动物类群的起源和早期演化研究提供了十分重要的信息。然而,该化石宝库中却很少见到作为“树干”的双胚层动物(即辐射动物)的化石记录,这给“真动物”的源头探秘蒙上了阴影。尽管广布于前寒武纪末期全球浅海域的“文德生物群”一直被认为是动物界早期一次“失败的演化试验”的牺牲品,但其中一支成功延续到早寒武世的春光虫(Stromatoveris)具有叠覆状梳齿构造,很可能代表着栉水母类的一类原始祖先。文中描述新的羽毛状动物王氏澄江海笔(Chengjiangopennawangii)不同于春光虫,前者具有彼此分离的羽枝,且羽枝上保存了排列规整的珊瑚个体虫室,因而与现代八射珊瑚中海笔类的形态学特征十分一致;新的谱系分析显示,它应该代表刺胞动物门中的一个原始类群。     

New records of temperate mollusks in two Late Pleistocene terrestrial localities from northeastern Oaxaca,Southern Mexico

The Mixteca Alta Oaxaqueña is in the state of Oaxaca, southern Mexico. This region is characterized by numerous Pleistocene fossiliferous localities. The objective of this study is to describe a diverse assemblage of Late Pleistocene freshwater and terrestrial mollusks in two localities from northeastern Oaxaca, Coixtlahuaca District. We identified 10 taxa of gastropods and one of bivalves. By the sedimentological characteristics and the mollusks assemblage, it is possible to relate the first locality with meandriform river deposits, without vegetation. The second locality was associated with a floodplain with short-lived associated vegetation. Five identified species constitute the most austral records of these taxa in Neartic Realm. In all the taxa, the Late Pleistocene occurrences constitute the last records of the identified mollusks in the study zone.