云南禄丰石灰坝地点的三趾马(Hipparion)化石

描述了产自禄丰石灰坝古猿化石地点的三趾马化石,分别归入两个种。其中一个种个体大、上颊齿窝内褶皱复杂且珐琅质厚、马刺呈不对称的多分叉状、次尖呈颈状收缩。根据上述特征组合将其归为西氏三趾马(Hipparion theobaldi (Lydekker, 1877)), 该种在南亚的西瓦里克地区也有分布。另一个种个体小、上颊齿褶皱复杂且珐琅质厚、下颊齿外谷窄而且浅。禄丰这一种与欧亚大陆、非洲和北美的三趾马均有明显差异,故将其定为禄丰三趾马(新种)(Hipparion (Hipparion) lufengense sp. nov.), 该种在西瓦里克地区亦有分布。根据这两种三趾马的齿冠高度及褶皱情况判断,两个种均向适应粗硬食物的方向发展。在这两个种生活的时期里,禄丰以森林环境为主,而西瓦里克地区则向草原化方向发展。因此推断这两个种在积极适应当地环境变化的同时也在为寻求更加适宜的环境进行长距离的迁徙。     

内蒙古东南部开鲁盆地晚白垩世嫩江组孢粉植物群

开鲁盆地白垩系发育,至今已有200余口探井钻遇到上白垩统,其中嫩江组滨浅湖相沉积地层厚度稳定,分布广泛,含较丰富的孢粉化石。通过对嫩江组孢粉化石的系统研究,建立了以Schizaeoisporites-BeaupreaiditesLythraites为代表的孢粉组合。孢粉组合和岩石组合的对比表明,开鲁盆地缺失松辽盆地嫩江组中上部地层。根据沉积特征和孢粉植物群面貌,对古植被、古气候和古环境进行了讨论,认为本区晚白垩世处于东北中生孢粉植物区南缘,孢粉植物群具有过渡性质,反应了偏干的暖温带—亚热带气候特征。     

Late miocene ostracodes (Ostracoda,Crustacea) from the Enikal Strait (Eastern Paratethys) as indicators of salinity changes

The species composition of ostracodes from the upper Maeotian and lower Pontian deposits of the Kerch-Taman Depression (Enikal Strait, Eastern Paratethys) is reported. The sedimentological and paleoenvironmental study shows that mass ostracode occurrences were controlled by hydrological changes in the Late Miocene brackish-water basins under consideration.     

"指示曲线"及其在恢复陆相古环境中的应用

在一定条件下,选择一些能够反映一定古环境的指示性化石类型,对其百分含量经过简单的算术运算,就可以绘制出一条能够反映一定环境变化的曲线。即指示曲线。它的优点是直接利用资料、计算方法简单,因此在制作曲线时减少了可能形成新的误差的因素。结果直观、可靠,能够比较准确地进行半定量的环境解释。它的缺点是应用范围局限,只有在满足沉积连续,化石丰富和足够的采样精度的条件下、选择出正确的指示分子,得出的结论才是可靠的。     

华北泥河湾盆地植被、气候与早期人类生存环境研究进展

中国北方泥河湾盆地可以与非洲奥杜威峡谷相媲美,它们具有十分相似的地质演化过程,这里河湖相沉积发育,并且蕴藏着丰富的古生物化石和大量古人类遗迹,是研究东亚早期人类生存环境变化的重要区域。基于前人积累的晚上新世以来植被、气候及早期人类生存环境的大量研究资料,经分析发现在大约2.6Ma(百万年),泥河湾盆地的植被由阔叶林转变为以针叶林为主;大约1.92 Ma以后,植被以温带森林-草原(主要是松属、蒿属及藜科)/温带草原(主要是蒿属和禾本科等)为主。通过对比发现,晚上新世以来中国北方从西部到中部,由森林转变为以森林-草原为主的植被类型出现的时段呈现明显的阶梯型。此外,泥河湾盆地气候出现了13个冷暖旋回, 15个干湿旋回,显著的冷干事件发生在2.8 Ma、2.6 Ma、1.92 Ma及143.8 ka (千年),湿润事件发生在43、32和6.6 ka。早期人类生活在森林-草原或以草原为主的植被环境中,气候冷暖干湿波动较大,水源丰富,大量哺乳动物共存。建议在建立泥河湾人类遗址更为精细地层的年代框架下,开展古气候温度与降水参数的定量化研究,将有助于精准重建古人类生存环境及揭示其变化规律。     

川西昌台地区上三叠统勉戈组的双壳类Pergamidia-Halobia群落特征及古环境分析

川西昌台地区上三叠统勉戈组上部为一套直接覆盖在流纹质火山岩之上的板岩,该板岩富集双壳类化石。化石保存完整,以食悬浮物质的外栖足丝型双壳类动物为主．根据优势属和常见属可建立一群落,即Pergamidia—Halobia群落。以根隆剖面为例．该群落的发展可分为3个阶段：第一阶段,群落中只出现了Halobia和Parapergamidia两个属．具有个体较小、数量较少的特点;第二阶段．群落中出现了12个属,以底栖双壳类Pergamidia为优势分子．Halobia仍是常见属,该时期群落具有个体较大、数量较多的特点;第三阶段。该时期群落组成分子相对第二阶段发生衰退,只剩下3个属,其中Halobia是常见属。岩石地层特征表明,该化石群落所在层位的沉积环境为火山活动末期的较深水环境。地球化学特征表明化石群落所在层位的岩石具有热水沉积的特点：常量元素的三元投点落人热水区域内及其附近;锰的含量较高;微量元素Si／Ba比值均小于1;铅、锌、钡、铷等金属元素含量明显高于地壳含量。综合分析表明．流纹质火山活动后期的热水活动是导致Pergamidia-Halobia群落发展的外界因素。     

Tetrapod Track Assemblage in the Hettangian of Sołtyków,Poland, and its Paleoenvironmental Background

Large theropod and sauropod footprints predominated in the continental Zagaje Formation (early Hettangian) exposed in the So?tyków outcrop. Geological and paleobotanical data indicate an inland seasonal habitat with low and high growing vegetation on the flood plain. The theropod-sauropod ichnofauna also contains occasional footprints of small ornithischians and mammals. The So?tyków track assemblage, together with other similar assemblages, suggests a wide range of habitats occupied by sauropods.     

Benthic foraminifers and paleoecology of a Holocene shelly concentration, Salado Basin, Argentina

Foraminiferal fossil assemblages of the shelly concentration, which represents the type section of Cerro de la Gloria Member of Las Escobas Formation, were analyzed for the first time. Taxonomic, quantitative and taphonomical analyses were made in order to obtain paleoenvironmental (physical as well biological) information. The complexity of the internal structure of the taphocoenoses was analyzed to infer the history of the final concentration process. The shell bed of Channel 15 corresponds to a shoreface longshore bar deposited in a brackish, unstable, wave-dominate coast. Shoreface and beach (foreshore) regressive facies were recognized. Taphonomic processes have modified the paleobiocoenoses by the selective preservation of autochthonous elements and by the addition of parautochthonous fauna from relict beachs and lagoons. Thus, the taphocoenoses is a within-habitat time-averaged assemblage composed of species that inhabit shallow shelf marine environments. Discrimination of autochthonous and parautochthonous fauna was possible based on taphonomic signatures of tests. The addition of the parautochthonous elements was related with longshore currents and littoral drift, and with high-energy events, probably with storm-waves, when erosion of the Pre-Mid Holocene substrate was more intense. Thus, the contribution of parautochthonous fauna is directly related with lithology and therefore, with dynamic of the paleoenvironment: in the shoreface, autochthonous fauna dominates in clastic sands with lamination and parallel stratification, whereas parautochthonous elements dominate in shoreface shelly gravels and in the foreshore sands. In the upper part of the section (beach facies), mainly parautochthonous elements related with erosion of the Pre-Mid Holocene substrate was recognized, since the shoreface was only periodically affected by marine processes, i.e., during storms.     

Organic-walled dinoflagellate cysts as paleoenvironmental indicators in the Paleogene; a synopsis of concepts

The organic-walled, hypnozygotic cysts of dinoflagellates (“dinocysts”) provide a rich, albeit incomplete, history of this eukaryotic plankton group in ancient sediments. Building on pioneering studies of the late 1970s and 1980s, recent ocean drilling and more detailed, integrated studies of surface sections have provided a wealth of dino-cyst data spanning the entire Paleogene. Based on multidisciplinary approaches, these studies have been instrumental in refining existing and furnishing new concepts of Paleogene paleoenvironmental and paleoclimatic reconstructions by means of dinocysts. Since dinocysts typically exhibit high abundances in neritic settings, the dinoeyst-based environmental and paleoclimatic information is complementary to that derived from typically more offshore groups such as planktonic foraminifera, coccolithophorids, diatoms, and radiolaria. While in a recent paper we gave a broad overview of case studies from around the globe (Sluijs et al. 2005), here we focus on a summary of these analyses and present a synopsis of applied paleoecological concepts in Paleogene (65–24 ma) dinocyst studies. Representing Earth’s greenhouse-icehouse transition, this episode holds the key to the understanding of extreme transient climatic change. The present paper offers guidelines for the application of dinocyst palaeoecology to the reconstruction of Paleogene sea-surface productivity, temperature, salinity, stratification, and paleo-oxygenation as well as their application in sequence stratigraphy, oceanic circulation and general watermass reconstructions.      

Benthic foraminiferal turnover across the Cretaceous/Paleogene boundary at Agost (southeastern Spain): paleoenvironmental inferences

We studied Upper Cretaceous and Lower Paleogene benthic foraminifera from the Agost section (southeastern Spain) to infer paleobathymetrical changes and paleoenvironmental turnover across the Cretaceous/Paleogene (K/P) transition. Benthic foraminifera indicate uppermost bathyal depths at Agost during the Abathomphalus mayaroensis Biochron (from about 400 kyr before the K/P boundary) through the early Plummerita hantkeninoides Biochron (about 120–150 kyr before that boundary). The depth increased to middle bathyal for the remainder of the Cretaceous, and remained so for the Danian part of the studied section (Parasubbotina pseudobulloides Biochron, at least 200 kyr after the K/P boundary). There were no perceivable bathymetrical changes at the K/P boundary, where 5% of the species became extinct, and the species composition of the benthic foraminiferal fauna changed considerably. Below the boundary, infaunal morphogroups constitute up to 65–73% of the faunas. Directly above the boundary, in the black clays of the lower Guembelitria cretacea Biozone, benthic foraminifera are rare. Several opportunistic taxa (e.g. the agglutinant Haplophragmoides sp.) have short peaks in relative abundance, possibly reflecting low-oxygen conditions as well as environmental instability, with benthos receiving food from short-lived, local blooms of primary producers. Above the clays through the end of the studied interval, epifaunal morphogroups dominate (up to 70% of the assemblages) or there is an even mixture or epifaunal and infaunal morphogroups. Infaunal groups do not recover to pre-extinction relative abundances, indicating that the food supply to the benthos did not recover fully over the studied interval (about 200 kyr after the K/P boundary). The benthic foraminiferal faunal changes are compatible with the direct and indirect effects of an asteroid impact, which severely destabilized primary producers and the oceanic food web that was dependent upon them.