晚上新世南海北部底栖有孔虫Bulimina alazanensis含量变化及其原因探讨

南海北部大洋钻探184航次1146站晚上新世以来的研究发现, 底栖有孔虫Bulimina alazanensis 的含量3.2～2.0 Ma BP逐渐减少, 并在2.1 Ma BP前后发生锐减, 其变化幅度达90%. 其他底栖有孔虫属种如Globobulimina subglobosa和Cibicidoides wuellerstorfi的含量则是在2.1 Ma BP之前较低, 而2.1 Ma BP之后增加. 对比浮游、底栖有孔虫的氧、碳同位素变化, 发现 B. alazanensis 的含量变化与氧、碳同位素的波动相对应: 当氧同位素值较轻, 即暖期时, 该种的含量处于峰值; 而当氧同位素值变重时, 该种含量也降低. 与碳同位素变化对比, 该种的高峰值分别与底栖有孔虫碳同位素的高值、浮游有孔虫碳同位素的低值对应. 结合北极冰盖扩张、东亚冬季风加强、表层生产力增加等诸多因素, 认为晚上新世由巴士海峡进入南海的深层水由较暖、溶解氧含量较高的西太平洋深层水团, 在2.1 Ma BP前后, 变为溶解氧含量较低的中层水团, 同时随着北极冰盖的扩张, 东亚季风的加强, 南海表层海水生产力增 加, 底层海水逐渐富营养且缺氧, 逐渐对B. alazanensis的生产形成压力, 导致该种自3.2 Ma BP开始含量逐渐降低, 并在2.1 Ma BP前后达到最低.     

追寻人类的足迹

自从达尔文提出进化论以来，人们对于自身的起源的研究就不曾间断过。近一个半世纪过去了，学术界对于人类起源与演化过程已经构建了一个粗略的轮廓。近年来，分子生物学方法的兴起加速了人类起源与演化的研究，但化石仍然是研究人类起源与演化最直接的证据。[编者按]     

Precambrian phosphatized embryos and larvae from the Doushantuo Formation and their affinities, Guizhou （SW China）

Weng＇an phosphates of the Precambrian Doushantuo Formation, Guizhou （southwestern China） preserve a large number of exquisite biological structures, which are mostly micro-spherical and represent seaweeds, acritarchs and developing eggs related to various groups of metazoans. Here is a report of a variety of developing eggs and larvae, which are most probably of Cnidarian affinity. The eggs examined in the study are composed of early cleavage embryos and two-layered gastrulae. The early cleavage embryos are radial and total cleavage with equal-size blastomeres. The gastrulae mostly bear a large archenteron, which is filled with yolk-degrading organic matter. Ovoid to fusiform planula-like larvae identified in thin sections under light microscope are mostly mouthless and their gastrovascular cavity is filled with possible yolk-degrading organic matter. They are likely representatives of non-feeding larva. The uncommon planula-like structures are hollow, with each having a mouth-like structure on its narrow end. We interpret them as feeding larva. Study of these embryos with possible Cnidarian affinities shed new insight on the origin of metazoans.     

热力洼地与沙尘暴的形成

沙尘天气自古以来就有,而且影响范围很广.我国长江以北几乎所有的地区都不同程度遭受沙尘天气的影响.     

Magnetic records of Core MD77-181 in the Bay of Bengal and their paleoenvironmental implications

Located in the low latitude region of the northeastern Indian Ocean, the Bay of Bengal represents one of the largest marginal seas in the world. The Bengal Fan hosts erosional products mostly from Himalayas and is under the influence of the Indian monsoon system. The Bengal Fan has thus been one of the ideal places for studying the uplift of the Tibet Plateau and the history of the Indian monsoon[1―8]. The intensity of the Indian monsoon is controlled by secular variations in insola- ti…     

A subfossil chironomid-total phosphorus inference model for lakes in the middle and lower reaches of the Yangtze River

Quantitative environmental reconstruction using subfossil chironomid has attracted much attention in recent years[1]. Consisting of about 400 genera, chi- ronomids (Diptera: Chironomidae) are found in nearly all freshwater bodies[2]. They are holometabolo…     

Microtubular metazoan fossils with multi-branches in Weng’an Biota

Microtubular metazoan fossils with multibranches are found at least 4 times from the Sinian （Ediacarian） Doushantuo Formation at Weng＇an, Guizhou, China. Their living mode should be the benthonic colony with higher ability of asexual reproduction. The inner of the tube with cross-walls and chamber shows that these fossils are basal or stemgroup cnidarians, similar to extinct tabulates. The multi-branching microtubular fossils are real metazoan found from Weng＇an biota, which is very important for studying the origin and evolvement of metazoan.     

中生代哺乳动物吞食小恐龙的化石证据

人们通常认为中生代的哺乳动物(生活在大约2亿年至6千5百万年前)都是像老鼠一样大的小动物,它们昼伏夜出,以昆虫为食,委屈地生活在恐龙的阴影下。由于世界各地发现的中生代哺乳动物化石零散、稀少,对于它们的形态特征、演化关系以及相关问题的了解也非常有限。因此,中生代哺乳动物一直是古生物学研究的热点之一。近年来,在中国辽宁西部早白垩世地层中发现了三尖齿兽类、对齿兽类、多瘤齿兽类、后兽类和真兽类等五大类哺乳动物的多具完整骨架,为研究哺乳动物早期演化与分异、探讨它们的系统发育关系提供了可靠的化石证据,也使得辽西成为研究…     

中国南方古瓷窑遗址保护实践的探索--记大窑龙泉窑遗址保护工程设计

瓷器是中国文化的象征之一。我国制瓷史的发展从未间断，窑址古迹的遗存极为丰厚。由于窑遗址中残存的历史信息最为丰富，是文物研究者们考察古代制瓷技术最可信赖的资料。窑遗址的历电价值和科学价值极为突出，是研究我国陶瓷相关研究的重要实证。保护窑遗址有助于促进我国陶瓷相关科学研究的深入。     

Tingia unita sp. nov. （Noeggerathiales） with strobilus from the Lower Permian of Wuda, Inner Mongolia, China

A number of specimens recently collected from the Early Permian Shanxi Formation of Wuda, Inner Mongolia demonstrate that the leafy shoot and strobilus of Tingia unita sp. nov. are both sprouting from a common stem, and consequently improve our understanding of the whole plant mor- phology of this enigmatic taxon of the Cathaysian flora. The strobili are cylinder-like, 1.7-2.5 cm in diameter and over 20 cm in length, with a basal stalk 7―8 mm in width and about 7 cm long. Sporophylls are verticillate, with approximately 8-10 in a whorl. On the adaxial side of each sporophyll a sporangium is attached. The strobilus is heterosporous and the microspores are of the Punctatisporites type. Large leaves vary from linear to oblong with entire lateral margins but are slightly lobed at the apex. Small leaves are generally the same as the large leaves but much narrower. The whole plant is probably a small arborescent tree with leafy shoots and strobili forming a crown, rather than a water plant with larger leaves floating on the surface of the water as previously understood. Features of the new species are in favor of the close affinity between Tingia Halle and Noeg- gerathiales, and accordingly the affinity of Noeg- gerathiales to Progymnospermophyta.