A Palynological Survey of Neogene Strata in Xiaolongtan Basin,Yunnan Province of South China

A palynological investigation of 24 samples from the representative Neogene strata of the Xiaolongtan Basin (23°48′N, 103°ll′E) were novelly carried out. Pollen samples were collected from the strata of N1 (clay, sandstone and conglomerate), N2 (clay intercalated with thin bedded lignite at the lower part, and coal bed at the upper part), N3 (marl), and N4 (clay intercalated with thin bedded lignite) in ascending order respectively. Pollen flora was characterized by the predominant appearance of angiospermous elements, representing the parent plants of evergreen broad-leafed types. Variations in the pollen flora were recognized between sample 15 and 16, as more herbaceous pollen of the Compositae types increasing upward in the strata, while certain woody types were minimized or even disappeared, thus dividing the pollen flora into two subzones. According to the current study, the geological age of the flora was suggested to be Middle-Late Miocene (Subzone A) to Early Pliocene (Subzone B), and the inferred vegetational type was evergreen broad-leafed forest, accompanied by a few deciduous elements.     

Astronomical dating of the Xiantai, Donggutuo and Maliang Paleolithic sites in the Nihewan Basin (North China) and implications for early human evolution in East Asia

Magnetostratigraphic studies have established a first-order chronological framework for the Paleolithic sites in the Nihewan Basin (North China), which enabled tracking early human evolution in East Asia. However, to fully understand how well early humans were adapted to climate change, a truly precise dating of the Paleolithic sites is required. Here, we established a high-resolution astronomical timescale for the Xiantai and Donggutuo fluvio-lacustrine successions at the eastern margin of the Nihewan Basin employing low-field magnetic susceptibility (χ) as a climatic indicator, aiming to further refine the ages of the Xiantai, Donggutuo and Maliang Paleolithic sites. Starting from an initial age model constrained by geomagnetic reversals, larger-scale χ cycles were firstly tuned to orbital obliquity using an automatic orbital tuning method. This first-order tuning was followed by simultaneously tuning χ to both obliquity and precession. The finally tuned χ records can be correlated almost cycle-by-cycle with the quartz grain-size record of the Chinese loess sequence and the marine δ¹⁸O record. The astronomically estimated age of the Xiantai Paleolithic site is ca. 1.48 Ma, corresponding to paleosol layer S₂₀ of the Chinese loess sequences or marine oxygen isotope stage (MIS) 49, an interglacial period. The astronomical estimate for the Donggutuo Paleolithic site ranges from ~ 1.06 Ma to 1.12 Ma, corresponding to paleosol/loess layers S₁₁-S₁₂ or MIS 31-33, spanning both interglacial and glacial periods. The astronomically estimated age of the Maliang Paleolithic site is ~ 0.79 Ma, corresponding to loess layer L₈ or MIS 20, a glacial period. This astronomical finding further implies that early humans may have permanently occupied China as far north as 40^oN since at least 1.1 Ma, and before this time the occupation may be intermittent.     

围封对内蒙古锡林河流域羊草草原主要构成植物个体、枯落物及群落热值的影响

2010年8月,对中国科学院内蒙古草原生态系统定位站1979、1999和2004年围封的羊草样地进行取样,测定植物个体、枯落物及群落的热值,探讨不同围封时间对羊草草原主要构成植物、枯落物、群落热值及单位面积能量积累量的影响.结果表明:围封对羊草草原主要植物个体、枯落物、群落热值及单位面积能量积累量均具有显著影响.1979和1999年围封的羊草草原单位面积能量积累量显著高于2004年围封,2004年围封群落和枯落物的热值均显著高于1979和1999年围封,而1979和1999年之间无显著差异.在不同围封时间下,同种植物的热值差异显著,而不同种植物的热值则表现出一定差异;群落热值高低取决于构成植物,而单位面积能量积累量主要由草地的生物产量决定,二者的变化趋势均为短期内有一定波动,长期围封之后基本维持在一个较稳定的水平,最终达到生态能量平衡.     

1975-2020年疏勒河流域绿洲时空变化研究

掌握内陆河流域绿洲时空动态是内陆河流域实现水资源优化配置和动态管理的基本前提。基于Landsat系列数据,结合面向对象随机森林和目视解译方法,分析了1975-2020年疏勒河流域绿洲的时空格局、结构变化及其成因,并探讨了人工/天然绿洲比例变化对生态环境的影响。结果表明：（1）2020年疏勒河流域绿洲面积为5790.24km²,占流域面积比例的4.65%,其中人工绿洲、自然绿洲和过渡带分别占绿洲总面积比例为45.29%、51.07%和3.64%;（2）疏勒河流域绿洲分布模式主要为内陆河沙漠区模式和干流模式;（3）1975-2020年疏勒河流域绿洲面积整体上呈扩张趋势,且绿洲变化以人工绿洲扩张、天然绿洲和荒漠-绿洲过渡带减少为主要特征,土地类型的主要变化为草地和荒漠被开垦,绿洲变化可分为1975-2000年缓慢扩张和2000-2020年迅速扩张2个阶段,主要原因为流域径流量增加和外来移民输入;（4）随着人工与天然绿洲面积之比由3：7（1975年）增加到5：5（2020年）,流域绿洲生态环境质量呈现先上升后下降趋势,2005年达到最高。研究可为疏勒河流域绿洲生态系统稳定发展提供数据支撑和科学依据。     

A new egg with avian egg shape from the Upper Cretaceous of Zhejiang Province,China

A new egg is described from the Upper Cretaceous lacustrine deposit of the Chichengshan Formation in the Tiantai Basin, Zhejiang Province, southeast China. The new specimen shares eggshell micro-features with members of the oofamily Stalicoolithidae, Paraspheroolithus of the oofamily Spheroolithidae and Mosaicoolithus (oofamily indet.), with barrel-shaped cones, prolatocanaliculate pore system, horizontal accretion lines and light stripes throughout the eggshell. However, the new egg differs from the aforementioned ootaxa by its small size and asymmetrical shape, revealing new morphological variation among eggs with microstructure similar to that of Paraspheroolithus, Mosaicoolithus and Stalicoolithidae. We refer the new egg to a new oogenus and oospecies, thus increasing the diversity of the Tiantai Basin oofauna. The Tiantai Basin has yielded a variety of dinosaur eggs and one turtle clutch. Comparatively, the new egg is surprisingly small and ovoid, a morphology usually associated with avian eggs, although the absence of a squamatic layer excludes the egg from being referred to this group.     

Palynostratigraphical dating of the Lower Cretaceous Peñaferruz Formation,San Pedro de Antromero Beach (Asturias Region,northwestern Iberian Peninsula)

A palynological assemblage of five Lower Cretaceous stratigraphic levels corresponding to the Peñaferruz Formation in San Pedro de Antromero Beach, has been studied to determine the exact age of this formation. An age no older than the Aptian is suggested on the basis of the palynoflora, based on the presence of Trilobosporites hannonicus, Cicatricosisporites venustus, Cicatricosisporites berouensis, Ephedripites dudarensis, and Reticulisporites semireticulatus. This age assignment implies a new relationship between the Peñaferruz and Antromero formations, the Peñaferruz Formation being younger than previously thought. This possibly makes both formations contemporaneous, at least at the San Pedro de Antromero Beach section, suggesting a lateral change of facies between these deposits.     

柴达木盆地上新世伍氏献文鱼(Cyprinidae:Schizothoracinae)形态学再研究

柴达木盆地是研究青藏高原古环境和动物演化历史的一个关键区域。为了适应上新世时期柴达木盆地环境的干旱化,化石裂腹鱼类伍氏献文鱼(Hsianwenia wui)演化出了异常粗大的骨骼。然而,人们对于这种骨骼增粗现象(pachyostosis)的性质仍知之甚少。为了进一步认识这一特征及其生理学机制,对伍氏献文鱼进行了详尽的形态解剖学工作,并识别出了一些新的信息:脑腔前部分叉的嗅束通道、韦伯氏器上发达的第3髓上骨、第5尾前椎支持众多尾鳍短鳍条以及第2尾前椎上一个附加的髓弓(棘)。此外,发现献文鱼骨骼的增粗存在差异性:该现象仅见于内骨骼,外骨骼(膜质骨)一般未见增粗;在成组增粗的内骨骼(如肌间骨:上髓弓小骨和上肋小骨)中,腹侧骨骼较背侧增粗更为明显。伍氏献文鱼匙骨后缘有一个显著而独特的位于胸鳍上方的"肩突"(humeral process),对比现生鲤科鱼类咀嚼活动中相关肌肉和骨骼的联动关系,认为这个"肩突"的出现与伍氏献文鱼咽颌骨骼(第五角鳃骨)增粗以及研磨坚硬的食物有关。     

Immigrant and native? The case of the swamp foxtail Cenchrus purpurascens in Australia

Aim

Spring wetlands in arid regions of Australia provide habitat for many highly endemic organisms, including fish, molluscs, crustaceans and plants, but these unique ecosystems have been under pressure since the arrival of Europeans about 250 years ago. Arguments over whether particular plant species are long‐term spring inhabitants or recent immigrants are confounding efforts to conserve spring flora. One such example is the swamp foxtail, Cenchrus purpurascens, a grass that is variably listed in the literature as being native to Australian wetlands or as being an introduced weedy species from Asia.

Location

Australia, China and Korea.

Methods

We use DNA sequences of the nuclear ITS and the chloroplast DNA regions trnL‐F and matK, complemented with newly designed simple sequence repeat (SSR) markers, to assess the native status of C. purpurascens in Australia and determine whether there is genetic differentiation among spring populations.

Results

We find that, although there has been gene flow between Asia and Australia in the geological past, the populations are now strongly differentiated: C. purpurascens has probably been present in Australia through the Pleistocene. In Australia, there is also strong genetic differentiation among populations from different springs, and between springs and non‐springs populations, indicating long‐term occupancy of some springs sites.

Main conclusions

Cenchrus purpurascens was present in Australia well before European colonization of the continent. The level of genetic differentiation among populations enhances the existing conservation values of Elizabeth Springs, Edgbaston, Doongmabulla and Carnarvon Gorge springs complexes within the Great Artesian Basin.