Fourier Analysis Applied to Mimomys (Arvicolidae, Rodentia, Mammalia) First Lower Molars – Biochronological Implications

Fourier analysis was used in this study to help a specific determination of some Mimomys (Arvicolidae, Rodentia, Mammalia) species. Several Pliocene and Pleistocene Central and Western European Mimomys species first lower molar contours have been decomposed by Complex Discrete Fourier Transform. Inter- and intra-specific comparisons have been performed on the harmonics obtained from the decomposition and some problematic specimens have been classified.     

Integrated Radiolaria,benthic foraminifera and conodont biochronology of the pelagic Permian blocks/tectonic slices and geochemistry of associated volcanic rocks from the Mersin Mélange,southern Turkey: Implications for the Permian evolution of the northern Neotethys

Blocks and tectonic slices within the Mersin Mélange (southern Turkey), which are of Northern Neotethyan origin (Izmir–Ankara–Erzincan Ocean (IAE)), were studied in detail by using radiolarian, conodont, and foraminiferal assemblages on six different stratigraphic sections with well‐preserved Permian succesions. The basal part of the Permian sequence, composed of alternating chert and mudstone with basic volcanics, is assigned to the late Asselian (Early Permian) based on radiolarians. The next basaltic interval in the sequence is dated as Kungurian. The highly alkaline basic volcanics in the sequence are extremely enriched, similar to kimberlitic/lamprophyric magmas generated at continental intraplate settings. Trace element systematics suggest that these lavas were generated in a continental margin involving a metasomatized subcontinental lithospheric mantle source (SCLM). The middle part of the Permian sequences, dated by benthic foraminifera and conodont assemblages, includes detrital limestones with chert interlayers and neptunian dykes of middle Wordian to earliest Wuchiapingian age. Higher in the sequence, detrital limestones are overlain by alternating chert and mudstone with intermittent microbrecciated beds of early Wuchiapingian to middle Changhsingian (Late Permian) age based on the radiolarians. A large negative shift at the base of the Lopingian at the upper part of section is correlated to negative shifts at the Guadalupian/Lopingian boundary associated with the end‐Guadalupian mass extinction event. All these findings indicate that a continental rift system associated with a possible mantle plume existed during the late Early to Late Permian period. This event was responsible for the rupturing of the northern Gondwanan margin related to the opening of the IAE Ocean. When the deep basinal features of the Early Permian volcano‐sedimentary sequence are considered, the proto IAE oceanic crust formed possibly before the end of the Permian. This, in turn, suggests that the opening of the IAE Ocean dates back to as early as the Permian.     

中国新近纪大型植食性哺乳动物演化和生物地层

中国新近纪大型植食性哺乳动物包括长鼻目、蹄兔目、奇蹄目、偶蹄目4个目至少32科,超过300种。它们在全球的演化和迁徙受到新近纪全球气候改变的驱动以及海陆分布的影响,各门类组成和地理分布由古近纪的古老面貌向第四纪的现代面貌转变。长鼻目和蹄兔目是非洲起源的类群;中国蹄兔目的种类和地史分布非常局限,但非常特化;中国的长鼻目则相当繁盛,成为长鼻类的第二演化中心和跨洲交流的十字路口。奇蹄目和偶蹄目是欧亚大陆起源的类群;相比古近纪,奇蹄类在新近纪持续衰落,但马科和犀科的多样性高,演化速率快,成为地层对比的标志性类群;偶蹄类则呈持续繁荣的状态,特别是反刍的优势使鹿科和牛科达到非常高的多样性,成为新近纪大型植食性哺乳动物中占优势的类群。中国新近纪大型植食性哺乳动物各门类中的现代类型均在山旺阶开始适应辐射,时间上对应于中中新气候适宜期,到通古尔阶中中新气候转型期开始多样性下降,在通古尔和灞河阶界线上发生了大型哺乳动物的灭绝和重组事件,90 % 的类群灭绝;至灞河阶下部,开阔生态系统成为中国北方的主导,产生了早期适应开阔环境的哺乳动物群,并逐渐扩散到全球;保德阶上部气候转湿润,诱发了南方哺乳动物群的北迁事件,并持续到高庄阶;至麻则沟阶开始出现了大量的现生属。青藏高原的隆升使当地在上新世时产生了适应寒冷气候的高原动物群,成为第四纪冰期动物群的先声。

     

中国东北、韩国东南和日本西南部早白垩世非海相与海相地层对比,非海相软体动物的生物年代学和古地理意义

根据非海相与海相,特别是共同的海相和非海相软体动物化石的对比,并结合放射性同位素测年,中国东北黑龙江东部和辽宁西部,韩国东南部庆尚盆地,日本西南部内带岐阜县北部牧户/庄川地区和外带四国德岛和物部地区早白垩世地层得到了对比,产自这些地层的非海相软体动物的时代也因此受到了约束。著名的中国东北含煤地层龙爪沟和鸡西群,盛产热河生物群/动物群的热河群的时代均为欧特里沃期/巴列姆期阿普特期,它们的上覆地层桦山群和孙家湾组为阿尔必期。韩国西南部新洞群和除金洞组以外的河阳群为阿普特期阿尔必期,不整合于新洞群之下的卯谷组主要为欧特里沃期。日本西南部内带的牧户/庄川地区的手取群和外带德岛和物部地区的物部川群均为欧特里沃期阿尔必期。Cuniopsis kihongi,Nakamuranaia leei,Koreanaia cheongi和Trigonioides(Wakinoa)tetoriensis的时代为欧特里沃期早巴列姆期。Viviparus onogoensis,Unio ogamigoensis,Myrene(Mesocorbicular)tetoriensis及Tetoria(Tetoria)yokoyami为欧特里沃期阿普特期。Arguniella cf.quadrata,A.cf.ventricosa,Sphaerium(Sphaerium)anderssoni,Probaicalia vitimensis和Pr.gerassimovi为欧特里沃期/巴列姆期阿普特期。Nakamuranaia chingshanensis,Plicatounio(Plicatounio)multiplicatus,Sphaerium(Sphaerium)coreanicum和Micromelania?katoensis为阿普特期阿尔必期。Nippononaia sinensis,Nip.tetoriensis,Nip.ryosekiana和Trigo-nioides(Wakinoa)wakinoensis是阿普特期的标志。Trigonioides(Trigonioides)quadratus,T.(T.)heilongjiangensis,Plicatounio(Plicatounio)naktongensis,Unio longus与Sphaerium(Sphaerium)chintaoense为晚阿普特期阿尔必期或阿尔必期的标志化石。我国东北、韩国东南和日本西南部非海相,特别是淡水软体动物接近的相似性表明这三地区在早白垩世时相连,并处于同一水系。但是,在欧特里沃期阿尔必期期间,这一陆块的东部,即频临古太平洋的日本西南部的外带因地势低而多被海水覆盖,在牧户/庄川和黑龙江东部存有遭受海侵的浅而窄的海湾,凡兰吟期,特别是欧特里沃期/巴列姆期之前,中国东北韩国东南部日本西南部陆块为受造山运动引起的隆起和沉降活动影响的高低不平的高原,经受了广泛而长期的剥蚀。多数含有包括熔岩和凝灰岩在内的火山岩,并与北东北北东方向的断裂带近于平行分布的非海相白垩纪盆地直至欧特里沃期/早巴列期(有些地区可能稍早(凡兰吟期))(134～126Ma),即华北克拉通破坏的高峰期(130～120Ma)才形成。这一现象表明,这些盆地受断裂,特别是伴随有强烈火山喷发和时而局部海侵的沿着古太平洋西北缘和郯庐断裂带的构造运动的控制。     

更新世代表性哺乳动物群的生物年代排序及与测年值的对比

哺乳动物随着环境的变化不断演化出与原来不同的特征, 因此可以根据化石标本的形态特征判断它们在系统演化中的位置, 并根据动物群中各个种类的演化程度判断不同动物群之间的生物年代顺序。本项研究在传统的绝灭率、共有属种、二元相似性系数等方法的基础上尝试拓展了二元共有度和排序梯度等共9种方法, 对选自中国境内有代表性的15个更新世哺乳动物群进行了生物年代排序。自老至新的动物群以其产地为名的生物年代合意顺序及推测的绝对年龄为: 泥河湾下沙沟(1.75~2.2 Ma)-繁昌人字洞(1.7~2.1 Ma)-巫山龙骨坡(1.5~1.9 Ma)-元谋人遗址(1.4~1.8 Ma)-建始龙骨洞(1.3~1.6 Ma)-柳城巨猿洞(1.15~1.5 Ma)-蓝田公王岭(1.1~1.3 Ma)-崇左三合大洞(0.6~1.2 Ma)-和县人遗址龙潭洞(490~800 ka)-周口店第一地点下部(460~770 ka)-周口店第一地点上部(230~450 ka)-海城小孤山(30~80 ka)-本溪山城子(约30 ka)-大连古龙山(27~30 ka)-周口店山顶洞(18~27 ka)。研究表明, 使用不同的方法对不同的动物群进行生物年代排序的结果在大尺度范围内是一致的, 但在小尺度范围内会出现一些差异, 这与排序标准和统计计算方法有关。一旦化石标本的分类鉴定结果和生物年代排序的方法确定下来, 动物群的生物年代序列就基本上是固定的, 不会随研究者的更换而改变, 因此可以用来检验绝对年龄的测年结果。由于组成各个动物群的种类可能会因鉴定人员的不同而有差别, 造成生物年代排序结果与测年结果差异较大。因此有必要组织同一团队的研究人员核对各个地点的化石种类鉴定结果, 并与测年工作配合进行。和县人遗址的龙潭洞动物群在本项研究的生物年代排序中早于周口店第一地点, 这个动物群的化石标本以及产出地层值得重新观察和测年。根据本项研究的实践, 这类数字化排序的方法还有细化的发展空间。

     

Magnetostratigraphy and revised chronology of the late Miocene mammal localities of Samos,Greece

The late Miocene mammalian record in Samos Island, Greece, is extremely important for the Eurasian Neogene mammalian history and chronology. However, due to the mixed nature of old fossil collections and controversies on the stratigraphic position of fossil quarries, great confusion has arisen concerning the recognition of distinct faunal assemblages, their age(s) and biostratigraphic significance. This paper presents the magnetostratigraphy of the late Miocene continental deposits of the fossiliferous Mytilinii Basin, Samos Island, Greece. Old and new sites are stratigraphically controlled with accuracy and correlated with each other. The magnetostratigraphy of seven individual sections, covering the entire Mytilinii Formation, provides good correlation with the Geomagnetic Polarity Time Scale (GPTS). These results, as well as the relocation and precise litho- and magnetostratigraphic correlation of the old and new mammal localities, combined with new and reviewed paleontological data and thorough studying of the numerous radiometric dates, allowed us to define five biostratigraphic horizons. Their correlation with, and implications to the European Neogene mammal chronology ages and zones make up the following discussion and provides a modified determination of the middle Turolian (MN 12) boundaries.Abbreviations GPTS Geomagnetic Polarity Time Scale - IPGP Institute de Physic du Globe de Paris - MGL Musée Cantonal de Géologie, Lausanne - MNHA Museum of Natural History of the Aegean, Samos - BMNH Natural History Museum of London - Q quarries - Fm Formation     

宁夏同心丁家二沟哺乳动物群生物地层学研究进展及青藏高原隆升背景

宁夏同心丁家二沟哺乳动物群是中国中中新世早期最具代表性的地方动物群,但长期以来,对这一动物群产出层位的认识处于模糊和混乱的状态。本文通过对丁家二沟一带新生界地层的划分和对比,将出产丁家二沟动物群的彰恩堡组划分为下、中、上3个层位,其中下部和中部的层位分别产出两个时代不同的动物群：下部的印子岭动物群以Alloptox gobiensis-Protanancus tobieni-Caementodon tongxinensis-Turcocerus sp.1组合为代表,时代对应于欧洲陆相哺乳动物分期的MN5;中部的马二嘴子沟动物群则以Alloptox gobiensis-Platybelodon tongxinensis-Hispanotherium matritense-Turcocerus sp.2组合为代表,时代对应于欧洲陆相哺乳动物分期的MN6;而上部的地层则需要进一步研究划分。同时,丁家二沟地区彰恩堡组的下部层位的时代约为17~15Ma,跨越了中中新统的下界,可以考虑在这一地区重新建立中国陆相通古尔阶下界,使其与中中新统的下界相一致。此外,丁家二沟地区北部彰恩堡组与下伏清水营组成不整合接触,南部干河沟组中发育了生长断层,可能代表了这一地区对约20Ma和10Ma青藏高原两次强烈构造事件在东北部的远程响应。     

Maeotian mammalian localities of Eastern Paratethys: Magnetochronology and position in European continental scales

The Maeotian of Eastern Paratethys corresponds to the interval of the magnetochronological scale from the base of the subchron C4Ar2n to upper parts of the Chron C4n (9.6–7.5 Ma). Fission-track dates of Maeotian deposits are in general agreement with paleomagnetic chronology. In the continental stratigraphic scale of Western Europe this interval corresponds to zones MN10 (save the lowermost parts), MN11, and MN12 (upper part). Taking into account age estimates of MN zones boundaries established in Western Europe, the East European mammalian localities of Ukraine and Moldova can be stratified as follows: MN10, Raspopeni, Grebeniki, Novaya Emetovka 1, ?lower bed of Ciobruci; MN11, Novaya Emetovka 2; MN12, Cimislia, Ciobruci upper bed, Cherevichnoe, Tudorovo, Dzedzvtakhevi, and sites in the lower Pontian deposits. The faunal criteria used to distinguish MN zones in Western Europe cannot be completely applied to sites of the Eastern Paratethys because of paleozoogeographic distinctions between West and East European provinces. Specific criteria of zone boundaries definitions should be developed for the East European province.     

Character, Age and Ecology of the Hezheng Biota from Northwestern China

1 Introduction In recent years, field works in the Hezheng area resulted in an explosive growth of new knowledge of Chinese mammalian faunas of the Late Cenozoic. A continuous sedimentary sequence from the Oligocene to the Pleistocene is developed and exposed in the Linxia Basin, Gansu Province, which contains a large number of mammal fossils. The Hezheng area comprises almost the whole Hezheng County, the western half of Guanghe County, the southern half of Dongxiang County, Linxia C…