Tetrapod association and palaeoenvironment of the Los Colorados Formation (Argentina): a significant sample from Western Gondwana at the end of the Triassic

The Los Colorados Formation constitutes a continuous continental succession deposited in Western Argentina during the Late Triassic, a time period that is crucial to the record of the faunistic turnover at the Triassic-Jurassic boundary. Many authors have pointed out that its rich tetrapod fauna represents a unique transitional assemblage with elements typical of both Late Triassic and Early Jurassic. However, the possibility that the fauna represented a mixture of Triassic and Jurassic horizons was also proposed. Recently, stratigraphic control of the fossiliferous levels was developed in order to correlate the different localities of the extense Los Colorados outcrops, and a revision of the taxonomic status of most tetrapods recovered is currently undergoing. Preliminary results confirm previous assumptions about the transitional nature of the assemblage where typical Triassic taxa are associated with dinosaur groups known from Early Jurassic levels in other Gondwanan areas. The fossiliferous levels of the upper third of the sequence included several basal archosaurs (aetosaurs, rauisuchids, sphenosuchians), protosuchian crocodiles, dinosaurs (sauropodomorphs, tetanuran theropods), derived therapsids and primitive chelonians. New evidence about tetrapod ichnites of chirotheroid affinities is added to the fossiliferous association.     

Methodological advances in the use of faunal gradient analysis for regional high-resolution correlation in the type Cincinnatian Series (Upper Ordovician)

Historically, strata of the type Cincinnatian Series have not been correlated with precision because of an assumption that individual beds are not regionally persistent. In an effort to establish a regional chronostratigraphic framework for the Cincinnatian, a technique has been developed recently that uses gradient analysis of fossil abundance data to compare vertical trends in biotic composition among five localities that span a distance of 65 km. Using faunal data to establish correlations below the meter-scale has been problematic, because variability in the lateral expression of many beds has made it difficult to sample equivalent fossiliferous strata at all localities.

Here, this correlation technique is modified in an attempt to draw meter-scale correlations of the Kope and lower Fairview Formations. This modification involves grouping fossil census samples into stratigraphic intervals, such that the stratigraphic spacing of samples is identical at all localities. Samples are binned using two protocols: one that groups samples into 0.5 m thick intervals, and another that groups samples by lithologically delineated meter-scale cycles. Gradient analysis of binned samples using both protocols produces curves in which patterns in faunal composition below the meter-scale can be correlated with success only for limited intervals at select localities. The inability to consistently correlate at high resolution might indicate that correcting for regional variations in the expression of strata is not enough. Alternatively, the ability to correlate some intervals below the meter scale suggests that other problems, such as fine-scale lateral variations in biotic composition, might be impeding correlation. In addition, gradient analysis techniques are employed at a new locality to extend the lateral breadth of the existing, broader-scale chronostratigraphic framework by approximately 40 km. Although interpreted to be in an up-ramp direction from previously measured localities, this new locality does not have an overall shallower water faunal assemblage until just below the Kope/Fairview contact.     

Chitinozoan biostratigraphy of the Upper Ordovician Fågelsång GSSP, Scania, southern Sweden

In the Fågelsång section, the new Global Stratotype Section and Point (GSSP) for the base of the Upper Ordovician Series, 22 samples from the E14 (a, b and c) and E15 outcrops have been studied for chitinozoans. They yield rich and rather diverse species assemblages of this microfossil group. The approximately 16-m-thick sampled part of the section can be subdivided, from bottom to top, into two biozones and a subbiozone: the Laufeldochitina stentor zone, the Eisenackitina rhenana subzone and the Lagenochitina dalbyensis zone. The boundary between the lowest biozone and the subzone is situated 1.7 m below the marker “Fågelsång Phosphorite” bed, thus only slightly lower (0.3 m) than the base of the Nemagraptus gracilis graptolite biozone, which defines the base of the Upper Ordovician Series. The base of the L. dalbyensis zone is located just above the Fågelsång Phosphorite, remarkably low compared to the graptolite biostratigraphy. It is evident that the chitinozoan biozonation provides an additional tool to recognise the base of the Upper Ordovician in this section. Furthermore, a distinct faunal change is shown across the phosphorite bed, possibly indicating a hiatus.     

内蒙古上白垩统二连组一长颈的镰刀龙类(英文)

镰刀龙类 (又称“懒龙”)是一类奇特的植食性兽脚类恐龙 ,化石记录主要局限于亚洲白垩纪地层中。由于镰刀龙类极其特化的形态和化石材料的局限性 ,这类恐龙的系统位置存在较多的争议。最近的发现 (RussellandDong ,1 994;Xuetal.,1 999)表明这类恐龙属于虚骨龙类 ,但其更为具体的系统位置依然存在争议 (Sues ,1 997;MakovickyandSues,1 998;Xuetal.,1 999;Sereno,1 999)。新发现于内蒙古苏尼特左旗赛罕高毕上白垩统二连组的镰刀龙类化石材料代表这类恐龙的一个新属种。杨氏内蒙古龙 (Neimongosaurusyangigen .etsp .nov .)的正型标本为一较为完整的骨架 ,是已知镰刀龙类当中第一件在同一个体中保存了大多数脊椎和几乎所有肢骨的标本。依据以下特征将内蒙古龙归入镰刀龙超科 :U形的下颌联合部、齿骨前端向下弯曲、齿骨前部没有牙齿、牙齿有一个收缩的基部、近圆形的齿根和叶形的齿冠、前部颈椎的神经脊低矮而轴向较长、后部颈椎背视呈X形、肱骨近端角状、肱骨有后转子、肱骨的尺骨髁和挠骨髁位于前部并为一狭窄槽分开、肠骨的耻骨柄细长而坐骨柄短以及跖部短。内蒙古龙的以下特征区别于其他镰刀龙类 :前部尾椎的横突下部有一圆形的窝 ,桡骨二头肌结节非常发育 ,后足趾节近端跟部非常发育 ,胫骨的腓骨嵴长     

奥陶纪三叶虫凸面远瞩虫（Telephina convexa Lu）的眼

研究材料系自浙江江山晚奥陶世黄泥岗组硅质结核中的Telephina convexa Lu眼部内模和外模标本。使用SEM二次电子图像把眼部放大,发现其小眼体是透镜体,外形为正八角形的透镜体,正八角形的每一相间的部位为正方形的眼间体（interlens)所占据,它们填充在八角形小眼体顶角和底角外侧的空间。每一正八角形的边长为66．66μm,小眼体之间为四向两组垂直交叉排列。Telephina的眼是介于在叶虫复眼和聚合眼之间的一种特殊类型的眼。从眼的构造和形态来看,Telephina 应属于中远洋悬浮类三叶虫,与Cyclopyge近似。     

The Pleistocene subterranean volesTerricola (Rodentia) of Serbia and Montenegro

A general morphometrical analysis of the M₁ was conducted to identify the subterranean vole species found in Upper Pleistocene localities from Serbia and Montenegro, and to clarify the systematic position and the phylogenetic relationships between the different species in the Balkans. From the different localities studied, we can assign one population toMicrotus (Terricola) thomasi and the others to theM. (T.) subterraneus group. This study suggests thatM. (T.) grafi can be considered as a chronological sub-species ofM. (T.) subterraneus or as a different but phylogenetically very close species.     

GIS支持下岷江上游土壤侵蚀动态研究

利用TM数据,采用3S技术和通用土壤侵蚀方程(RUSLE)研究岷江上游地区3个典型时期的土壤侵蚀动态,并对影响侵蚀的主要因子进行初步分析.结果表明,研究区3个时期侵蚀面积分别占研究区总面积的1.2%、1.4%和1.70%;年平均侵蚀模数分别为32.64、1 04.74和1 362.11 t·km^-2,以微度侵蚀、轻度侵蚀为主,伴有少量的中度侵蚀.侵蚀面积比较小,侵蚀程度比较轻.侵蚀与坡度呈显著正相关,侵蚀大多发生在＞25°的区域,196年占总侵蚀量的93.65%,1995年为93.1%,2000年为92.71%;在海拔上,中山、亚高山、高山以及干旱河谷是侵蚀发生的主要地带,1986年占总侵蚀量的9.21%,1995年为97.63%,2000年为99.27%;不同类型的植被直接影响到侵蚀的发生,灌木林地以及新退耕的疏林地是3个时期侵蚀的主要发生地,过度放牧导致草场退化,也产生了微度侵蚀;侵蚀的发生和土壤类型密切相关,燥褐土、石灰性褐土最易发生侵蚀,是控制侵蚀的重点区域;人口的增长、户数的增加是侵蚀发生的驱动因子,人口与户数增长导致资源需求压力的增大,侵蚀呈线性增加.     

岷江上游不同景观结构小流域水量平衡的比较

研究了1988～2002年岷江上游两个小流域（镇江关流域和黑水河流域）不同景观结构（土地覆盖、海拔、坡度、斑块密度、最大斑块指数等）对水量平衡的影响.基于两个流域土地覆盖类型、1988～2002年多年平均降水量和蒸散量的空间分布、两个流域土地覆盖类型同期多年平均径流深度的数据,得到不同土地覆盖类型的海拔、坡度、坡向与降雨、蒸散、径流的关系.结果表明,两个流域有林地海拔、坡度、坡向的不同导致其降水、蒸散降水比、径流降水比各异;两个流域草地水量平衡对景观格局的响应模式与有林地基本一致;由于黑水河流域的耕地分布在干旱河谷中,其蒸散量远远大于降水量,耕地本身的景观结构（坡向、坡度,斑块密度）并不对其水量平衡产生影响,这一点与镇江关完全不同.     

周口店田园洞古人类化石点地层学研究及与山顶洞的对比

田园洞主体堆积厚度约2.5m,其动物群可分为上、下两个组合:上部组合物种多样性丰富,化石被啮齿类严重啮咬;下部组合化石种类单调,以鹿类和绵羊类为主,但化石丰富,极少有啮齿类咬痕。人类化石发现于下部组合;东洋界动物主要出现在上部组合,例如猕猴、猪獾、果子狸和鬣羚等。而马鹿和绵羊只出现于下部组合。沟齿鼯鼠和豪猪在下部组合开始出现,但主要发现于上部组合。梅花鹿是田园洞的优势种,在各个阶段都出现。通过统计比较,发现山顶洞3个地层单元(上室、下室和下窨)中所含化石属种基本一致,代表同一个动物群。尽管田园洞动物群中尚未发现可靠绝灭种类,但却有10种地区绝灭种,它与现生动物群有一定差异;而在堆积物特征及化石组合方面,与周口店山顶洞的更为接近。在田园洞和山顶洞出现的沟齿鼯鼠、猪獾、果子狸及鬣羚等是各自在华北地区的最早记录,可能代表了更新世末期自南而北的动物迁徙事件。     

萌蘖调控对辽东栎留存萌生株生长与结实的影响

比较了不同调控措施对岷江上游辽东栎萌生灌丛生长与结实的影响.结果表明,人为调控对辽东栎萌生灌丛本生长阶段的高生长与有性繁殖有着显著影响.各调控措施对辽东栎灌丛萌生株的基径增长未产生明显影响;保留2支和3支萌生株的丛高生长优势明显.调控丛的新生枝数量、总长度、总生物量较未调控前有较大增加,保留2支萌生株的丛类型增加得尤为显著;叶片数量、叶片总生物量与未调控前相比增加明显,叶片面积按保留萌生株数量由多到少逐渐变小.调控后,每丛保留3支萌生株的丛产生的种子最多,但自然状态丛种子单粒重最大.