New gastropod species from the Pleistocene of the Upper Don basin

Two new species of fossil freshwater gastropods, Borysthenia intermedia sp. nov. and Tanousia krasnenkovi sp. nov., from the Tiraspol deposits of the Middle Pleistocene of the Oka-Don Plain are described. Parafossarulus priscillae (Girotti, 1972), Viviparus diluvianus (Künth, 1865), and Lithoglyphus jahni Urbasnski, 1975 are reported from Russia for the first time. The status of some problematic species of freshwater gastropods from the Middle Pleistocene of the region studied is discussed. The chronological and environmental significance of all gastropods studied is given.     

内蒙古高特格上新世三趾马化石及其意义

描述了产自内蒙古高特格上新世地层中的三趾马属化石,分别归入两个种。下部层位的材料因吻部间颌突较高、犬齿粗壮并在其内侧前后缘形成嵴和沟、下颊齿齿冠较低、双叶较圆以及外中谷很深等特征而归入意外(笨重)三趾马(Hipparion(Baryhipparion)insperatum Qiuet al.,1987),其古地磁年龄为4.3Ma;上部层位的标本因下颊齿高冠、双叶贺风型、外中谷宽浅以及下马刺发育等特征而归入黄河(近)三趾马(H.(Plesiohipparion)huangheense Qiu etal.,1987),其年龄约为3.9 Ma。在此之前,这两种三趾马的分布局限,仅发现于山西榆社和陕西蒲城的上新世地层,高特格新材料的发现增加了人们对于其地理和地史分布以及特征演化的了解。此外,还对高特格颊齿标本进行了连续横切,结果显示,随着年龄增加H.insperatum的双叶一直较圆,下后尖逐渐大于下后附尖,但外中谷形态并不随磨蚀加深而有大的改变;H.huangheense的双叶稳定、贺风型,外中谷内端随着磨蚀的加深变得宽圆,下马刺渐弱而下反马刺逐渐显现,下内尖逐渐变得圆钝,其后的凹也逐渐变小。高特格地点相对较低齿冠的H.insperatum向极高齿冠的H.huangheense的转变,指示了内蒙古中部地区在上新世逐步干旱化和草原化的过程。     

Stable carbon isotope composition of bone hydroxylapatite: significance in paleodietary analysis

The stable carbon isotope composition of the structural carbonate derived from animal bone hydroxylapatite (δ¹³C_B-HA) could record an animal’s diet. These records provide critical evidence for different paleontological disciplines, e.g., paleodiet analyses, and paleoclimate reconstructions. Compared to those of other body tissues, such as bone collagen or teeth enamel hydroxylapatite, δ¹³C_B-HA values record information on the whole diet of an animal in its last years. δ¹³C_B-HA can be applied to fossil animals of various body sizes. The δ¹³C analytical instruments available only require that prepared bone samples be approximately 2–5 mg for precise measurement, allowing δ¹³C_B-HA analysis to be feasible on most vertebrate fossils without destructive sampling, especially on small mammals or birds whose teeth are not large enough for sampling or are lost. Moreover, δ¹³C_B-HA can be used from different times or under less than ideal burial environments. For fossils dating back to Devonian or buried in hot and humid regions, dietary information has been completely lost in bone collagen during post-depositional processes but still remained in the δ¹³C_B-HA values because hydroxylapatite is less influenced by diagenetic effects after deposition. In addition, systematic methods such as X-ray diffraction and Fourier transform infrared spectroscopy have been developed to qualitatively or semiquantitatively assess the influence of diagenesis on bone hydroxylapatite to ensure the credibility of the δ¹³C_B-HA values. With the above merits, δ¹³C_B-HA analysis is therefore becoming an increasingly important method in paleodiet-related research. Currently, applications of the δ¹³C_B-HA method on fossil animals are primarily focused on two aspects, namely, paleodietary reconstruction of fossil animals with uncertain diets and paleoenvironmental reconstruction based on the δ¹³C_B-HA values of fossil herbivores. The published researches, combined with our new results from early birds, demonstrate the considerable significance of the δ¹³C_B-HA method in paleontological and paleoenvironmental research. Notably, the δ¹³C_B-HA-based paleodietary analysis of early vertebrates, especially the large number of small birds or mammals discovered in the past decades would be an important work in the near future.     

Benthic foraminiferal ecomarker species of the terminal Cretaceous (late Maastrichtian) deep-sea Tethys

Benthic foraminiferal distribution patterns throughout the late Maastrichtian Tethyan deep sea are analyzed. Many species are ubiquitously distributed throughout this region and therefore it is hard to assess their ecological preferences. However, five species show distribution patterns, which suggest that they may have distinctive paleoenvironmental preferences. These preferences are interpreted from hypothesized surface circulation and upwelling patterns. Additional information comes from Recent benthic foraminiferal ecology and from responses to the Cretaceous/Paleogene (K/Pg) boundary event. This enables us to assess the ecological preferences of these late Maastrichtian taxa, and establish them as ecological-marker (ecomarker) species for paleoenvironmental interpretation of the late Maastrichtian bathyal-abyssal Tethyan realm.(1) Eouvigerina subsculptura is suggested to be indicative of reasonably oxygenated upper-middle bathyal environments, though with high abundance of utilizable organic matter. (2) Sliteria varsoviensis is linked to areas of late Maastrichtian upwelling and seems to have been an epibenthic species with an opportunistic life mode. (3) Gavelinella beccariiformis and (4) Nuttallides truempyi are considered to be indicative of oligotrophic conditions unless they occur with a large proportion of endobenthic morphotypes. (5) Gavelinella pertusa is proposed to indicate neritic-middle bathyal environments of the ‘boreal’ realm, which might be influenced by more seasonal food-fluxes and by higher oxygen levels than similar settings in the (sub)tropics.Finally, the anomalous high abundances of the buliminid species Sitella cf. plana in deep open ocean environments is discussed in terms of possible mechanisms permitting such a (morphologically) opportunistic species to thrive in such an assumedly oligotrophic environment.     

新疆托克逊晚三叠世昆虫

记述了新疆托克逊晚三叠世昆虫化石14属17种。这一昆虫群代表了我国北方三叠纪昆虫的面貌,也是我国最丰富的三叠纪昆虫群之一。从其生态习性分析,这个昆虫群以生活于水中和岸边环境的种类为主,说明当时托克逊地区为一水域环境,气候也很适宜昆虫的生存。     

Reassessment of the paleoenvironment and preservation of hominid fossils from Hadar, Ethiopia.

Samples of paleosols from locality AL-333, known for numerous specimens of Australopithecus afarensis, were analyzed in order to reconstruct the original soils and environment of burial of the associated fossil hominids. The bones were found in swale-like features, within the calcareous and coarse-grained basal portion of a paleosol. This is more like an assemblage of bones buried during a single depositional episode, such as a flood, than an assemblage accumulated on a soil over a long period of time by carnivores or other means of death. What killed the hominids remains unclear, but considering the association of originally disarticulated bones of such hydraulically distinct types as phalanges and maxillae, it is very likely that they died and partially rotted at or very near this site. The paleosols at AL-333, here named the Fo and Go clay paleosols, have calcareous rhizoconcretions, granular surface horizons, prismatic peds, and shallow calcareous nodules and stringers like soils now supporting grassy woodland in semiarid regions. Although this group of hominids was buried in streamside gallery woodland, there is evidence from Laetoli, Tanzania, that A. afarensis ventured out into open wooded grassland as well. Evidence for this should be sought from other paleosols at Hadar.     

盐碱胁迫下羊草植硅体的形态变化

对6个不同盐碱度梯度环境的羊草(Leymus chinensis)群落中生长状况良好的羊草进行人工筛选, 选取其中长势相近、叶片大小一致的羊草叶片, 用湿式灰化法提取植硅体并对其进行分类和命名, 共统计植硅体3387粒, 鉴定出植硅体类型10类, 分别是平顶帽型、尖顶帽型、刺帽型、光滑棒型、刺棒型、似牛角棒型、尖型、板型、蜂窝状和其他类型。随着盐碱浓度的增加, 帽型、棒型、尖型、板型和蜂窝型都有不同程度的变化。帽型植硅体的百分含量都有不同程度的增加, 6组样品中同种形态植硅体的大小有一定差别, 植硅体的大小随着盐碱度的升高呈现出不同程度的变化, 总体上有增大的趋势。     

鄂尔多斯盆地三叠系延长组葡萄藻形态特征

鄂尔多斯盆地西南部西峰地区三叠系延长组主要烃源岩层长7^3-长7^2段发现大量藻类化石,丰度高,但分异度很低,属种单凋．主要由极其丰富的光球型疑源类（Leiosphaeridia）和丰富的葡萄藻（Botryococcus）组成。其中,葡萄藻形态各异．多为团块状,也有串珠状、云朵状的群体。团块状化石又可区分为球形、心形、三瓣形、品字形、菊花形等多种形态。透光镜下化石多为桔黄、棕红色。反射荧光强烈．大多呈黄色、浅黄褐色。葡萄藻化石可明显区分为淡水和做成水两种生态类型．前者群体及单个细胞较小,群体边缘呈波状或锯齿状,细胞放射状排列明显。后者群体及单个细胞较大．群体轮廓线较光滑,细胞放射状不十分明显。对葡萄藻生态环境分析和古环境对比研究认为．西峰地区中、晚三叠世葡萄藻繁盛的延长组长7段沉积时期．恰好是湖盆水域扩大,并逐步达到最大湖泛面的湖进期,气候温暖适宜．雨量充沛。两种生态类型葡萄藻化石的出现表明,延长组长7段沉积时期,湖水的盐度有一定的波动。通过对该层位共生疑源类和其他反映盐度地球化学指标的研究,认为中、晚三叠世鄂尔多斯湖盆正处于逐渐淡化过程．盐度的变化范围比较有限,为典型的淡水湖泊。延长组长8-长7段发现的孢粉组合的生态类型与我国云贵高原抚仙湖中与葡萄藻伴生的孢粉组合较为相似．表明鄂尔多斯盆地中、晚三叠世古湖泊处于较低地理纬度的暖温带-亚热带气候区。