Rare earth elements and carbon isotope geochemistry of the Doushantuo Formation in South China: Implication for middle Ediacaran shallow marine redox conditions

The middle Ediacaran Shuram excursion, the largest negative δ 13 C carb excursion in Earth history, has been interpreted as indirect evidence for episodic oxidation and remineralization of deep ocean DOC (dissolved organic carbon). It has been hypothesized that such oxidation event may have occurred when anoxic DOC-laden deep water was brought to shallow shelves during oceanic upwelling, which is expected to cause localized anoxia in shallow environments. To test this prediction, we systematically analyzed rare earth elements (REE) and δ 13 C carb of the upper Doushantuo Formation carbonates in the Yangtze Gorges area of South China, which were deposited in an inner shelf environment and record a large negative δ 13 C carb excursion correlated to the Shuram event. The REE data show a significant positive shift in Ce/Ce* values, synchronous with a pronounced negative δ 13 C carb shift. This positive Ce/Ce* shift is interpreted to represent an oceanic anoxia event in shallow shelf environments, which may have been caused by the upwelling or impingement of oxygen-depleted and 12 C-enriched deep water onto shelves. This anoxia event coincides with a sharp decline in the abundance and diversity of Ediacaran acanthomorphic acritarchs, raising the possibility that these two geobiological events may be causally related.     

The Lantian biota: A new window onto the origin and early evolution of multicellular organisms

The Lantian biota at the Lantian Town of Xiuning County,Anhui Province,is preserved in black shales of the Ediacaran Lantian Formation.It yields some of the oldest known complex macroorganisms,including fan-shaped seaweeds and possible animal fossils with tentacles and intestinal-like structures reminiscent of modern coelenterates and bilaterians.The Lantian Lagerst tte sheds new light on the origin and early evolution of multicellular organisms in relatively quiet and deep environments soon after the Neoproterozoic Marinoan glaciation.The morphological complexity and diversity of early multicellular organisms may be closely related to sexual reproduction and alternation of generations.The fluctuation of oceanic redox conditions during this period may have played a role in the ecology and preservation of the Lantian biota.     

Pyrite framboids associated with the Mesozoic Jehol Biota in northeastern China: Implications for microenvironment during early fossilization

Despite of the recent influx of reports describing important fossil specimens from the Mesozoic Jehol Biota, detailed information on the mechanism of fossilization and paleoenvironment in which these fossils were deposited is scanty. We present an analysis of microenvironment based upon scanning electron microscope observations of in situ pyrite framboids and microcrystallines of plant and vertebrate feather fossils in the Jehol Biota. Pyrite microcrystallines and framboids occur extensively inside and on surface of plant fossils.Framboids found on feathers and in sedimentary matrix were in a lower abundance. These framboids have diameters ranging from 6 μm to 31 μm with an average of 20 μm, indicating a dysoxic aqueous condition with free oxygen level less than 30 μmol/L for the microenvironment where these framboids were formed. The outgrowth of framboids inside plant tissues suggests the presence of water molecules and free oxygen at the cellular level during pyritization; the relative timing between tissue decay and framboid formation implies a rapid tissue degradation occurred during the very early stage of fossilization. This line of reasoning is consistent with the observation that cell level structure of plant fossils from these deposits is rarely preserved. We propose a "fossil envelop" model to accommodate the different geochemical conditions between the microenvironment surrounding the fossil material and the macroenvironment of background lake bottom water.     

Correlation between echolocation calls and morphological features among three kinds of bats

The correlation between echolocation sound and morphological features of 18 species of bats, which are subordinated to 3 families including rhinolophidae, hipposideridae and vespertilionidae is studied. Pearson's correlation and regression analysis are adopted to analyze the correlations between noseleaf width (NW) and forearm length (FAL), NW and dominant frequency (DF), FAL and DF. The results show a positive correlation between NW and FAL and a negative correlation between NW and DF in Rhinolophidae. In each family, there is a negative correlation between FAL and DF. Some species have a higher or lower frequency than predicted one according to their body size. There are significant differences of the regression equation of FAL and DF among the three families. For the bats with the same body size, the order in frequency is: hipposiderid bats＞ rhinolophid bats＞ vespertilionid bats. The mechanism of interrelationship between FAL and DF of bats, the reason why these deviations occur in correlativity of the three families and the mechanism of the interaction between morphological, physiological and ecological characteristics are discussed.     

Discovery of the budding phosphatized globular fossils from the Neoproterozoic Doushantuo Formation at Weng’an, Guizhou Province, China

There is much debate on biological affinities of the phosphatized globular fossils from the Neoproterozoic Doushantuo phosphorites at Weng’an, Guizhou Province. Here we report for the first time the budding structures of some of these globular fossils, which have previously been interpreted as the resting eggs and early cleavage embryos of metazoans. The budding structures are similar to the germinating tubes of the spore and zygote of living algae, suggesting that some globular fossils from the Doushantuo phosphorites bear affinity with algae. The present new information indicated various biological affinity of the phosphatized globular fossils from the Doushantuo phosphorites.     

Vermicular fossils in the Early Cambrian Xidashan Formation in the Quruqtagh region of Xinjiang, China

Large amounts of vermicular fossils and a minor amount of sponge animal fossils have been found in the Early Cambrian Xidashan Formation in the region of Quruqtagh, Xinjiang. Vermicular fossils are generally more than 50 mm long and 0.3?1.4 mm wide; their wrinkled lamellae are microfine with 3?10 pieces within the length of every each millimeter. The fossils are considered to be Sabellidites cambriensis Sokolov (1965). The Xidashan Formation is the highest stratum in which Sabellidites occur, as has been so far reported.     

Occurrence of Sciadopitys-like fossil wood （Coniferales） in the Jurassic of western Liaoning and its evolutionary implications

The genus Sciadopitys, containing a single species (S. verticillata), is the only extant representative of the Family Sciadopityaceae (Coniferales), and is a remarkable living fossil. Although some leafy fossils have been ascribed to Sciadopityaceae, fossil xylem material with a close affinity to this family is very rare, and there have been no fossils found showing both pith and primary xylem structures, which are of great importance for wood identification. Thus, it has been difficult to use fossils for the understanding of wood anatomy evolution in the sciadopityaceous plants over geological time. In this note we briefly report on Sciadopitys-like fossil wood found in the Middle Jurassic of western Liaoning, which bears well-preserved Protosciadopityoxylon-type secondary xylem, endarch primary xylem and heterogeneous pith. This is the first report of fossil specimens of the Sciadopityaceae with such detailed preservation of wood structures. The discovery provides precise anatomical evidence for reconstructing the evolu- tionary history and geographical distribution of Sciadopityaceae, as well as contributing to understanding of the fossil diversity of the Jurassic Yanliao Flora in northern China.     

The nonmarine environment of Quaternary foraminifers in Yanghuzhuang, China: Evidence from boron and strontium isotopes

The concentrations and isotopic compositions of boron and strontium of Quaternary foraminifera and bivalve fossils collected in the Yanghuzhuang section of Yanqing, Beijing and of modern gastropods living in the Guishul River and of river water were measured. The concentrations and isotopic compositions of Quaternary foraminifera and bivalve fossils differed from those of modern marine foraminifers and were similar to those of modern terrestrial gastropods from the Guishui Riven These results Indicate that early Quaternary foraminifera in the Yanghuzhuang section inhabited a nonmarine environment and that these foraminifera were not the result of a transgression or sea flooding. The foraminifera were not special halobios and can survive in the terrestrial condition that resembled those of the ocean.     

Lower Cambrian phosphatized Punctatus from southern Shaanxi and their ontogeny sequence

Phosphatized and three-dimensionally preserved embryos and spherical fossils of metazoan recovered from the Kuanchuanpu Member, Dengying Formation in southern Shaanxi, China provide nice devel- opmental sequence for the studies of origination, taxonomy, phylogenic evolution and developmental biology of early animals. Ontogeny of these larva fossils has not been systemically studied mainly due to their poor preservation and limited identification. The Kuanchuanpu Member, predominated by phosphorites and cherts, yields phosphatized animal embryos, particularly those of Olivooides and Punctatus which have high resolution in fine structures and different ontogeny developmental stages. An ontogenetic sequence of the Punctatus is established mainly base on its developmental transitions from body part to oral one, which is perfectly consistent with the embryonic ontogeny sequence pro- posed by Bengtson and Yue (1997). Furthermore, a new genus Quadrapyrgites gen. nov is erected to receive a larva with tetraradial body plan.     

Isotopic compositions of small shelly fossil Anabarites from Lower Cambrian in Yangtze Platform of South China: Implications for palaeocean temperature

Anabarites belong to small shelly fossils (SSF), which occur widely in the Lower Cambrian strata of Yangtze Platform in South China. They are phosphate shell in composition and represent the earliest stage of the Cambrian bioradiation of Bilateria, the so-called "Cambrian Explosion". In this study, we attempted to separate Anabarites fossils from Lower Cambrian dolostones, and we obtained samples of both the fossils (SSF) and the granular phosphates (GP). Isotopic analyses were performed on samples of SSF, GP, and matrix dolostone (DH-23). The results showed that the δ30Si values of the quartz filling in fossils celoms, and the siliceous materials in granular phosphates are -0.6‰ and -0.7‰, which is different from normal sedimentary siliceous rocks from the Lower Cambrian strata (0—0.7‰) as reported by Li et al., but is consistent with the data for siliceous rocks and cherts of submarine hydrothermal origin. It is likely that a later hydrothermal replacement could have taken place in the SSF-bearing sedimentary rocks. The oxygen isotope values of the phosphate of SSF and GP are 16.8‰ and 17.0‰, respectively. These are significantly higher than the Neoproterozoic phosphate ores (10.9‰—13.9‰) as reported by Ling et al., hence, late diagenesis and hydrothermal replacement may not have caused a significant change in the oxygen isotope compositions of the small shelly fossils, and the calculated temperatures (25.4—26.3℃) for palaeo-seawater using a SSF phosphate oxygen isotope thermometer are therefore considered here as the upper limit of seawater temperature in the Early Cambrian ocean of the Yangtze Platform.     

Doushantuo embryos preserved inside diapause egg cysts

Phosphatized microfossils in the Ediacaran (635-542 Myr ago) Doushantuo Formation, south China, have been interpreted as the embryos of early animals. Despite experimental demonstration that embryos can be preserved, microstructural evidence that the Doushantuo remains are embryonic and an unambiguous record of fossil embryos in Lower Cambrian rocks, questions about the phylogenetic relationships of these fossils remain. Most recently, some researchers have proposed that Doushantuo microfossils may be giant sulphur-oxidizing bacteria comparable to extant Thiomargarita sp. Here we report new observations that provide a test of the bacterial hypothesis. The discovery of embryo-like Doushantuo fossils inside large, highly ornamented organic vesicles (acritarchs) indicates that these organisms were eukaryotic, and most probably early cleavage stage embryos preserved within diapause egg cysts. Large acanthomorphic microfossils of the type observed to contain fossil embryos first appear in rocks just above a 632.5 +/- 0.5-Myr-old ash bed, suggesting that at least stem-group animals inhabited shallow seas in the immediate aftermath of global Neoproterozoic glaciation.     

A kind of coccoid dinoflagellates-like fossils gives a new explanation of source of dinosterane in the Early-Middle Cambrian

The coccoid fossils covered with thick gelatinous envelop containing several gametes are discovered in gyps and salt deposits of Cambrian, H₄ well and chert bed of the base of Yuertus Formation (∈¹₁) of Xiaoerbulake Section. The fossils are described and compared with coccoid dinoflagellates. These fossils may be a coccoid life-cycle stage (vegetative cyst) of coccoid dinoflagellates. If this identification is correct, the coccoid dinoflagellates-like fossils could give a reasonable explanation of the dinoflagellate-specific biomarkers from Cambrian, H₄ well, Tarim Basin.     

贵州新元古代瓮安生物群中动物胚胎化石研究进展

 瓮安生物群指产出于贵州瓮安磷矿地区新元古代埃迪卡拉纪陡山沱组（635~551Ma）上磷矿段的一个特殊磷酸盐化微体化石组合,主要由多细胞藻类、大型带刺疑源类和处于不同发育阶段的多种后生动物胚胎组成,并包括少量可能的后生动物幼虫和成体化石。瓮安生物群作为迄今为止世界上最古老的前寒武纪后生动物化石群,为探索后生动物的起源和早期演化历程提供了独一无二的实证记录。10余年来,瓮安生物群中动物胚胎化石的研究取得多项突破性进展,已确认至少5种不同卵裂方式的动物胚胎化石,胚胎化石分类从单纯的形态学分类向生物学分类转变,为揭示瓮安生物群中动物多样性提供了更多线索。同时,相关研究更新了繁盛于埃迪卡拉纪大型带刺疑源类生物属性的传统认识,并将之与有表面装饰的动物休眠卵（滞育胚胎）化石相联系。同步辐射X射线显微CT技术的应用成功解决了胚胎化石三维无损成像难题,为古胚胎学的发展带来了新的机遇。     

甘肃临夏盆地中新世地层及哺乳动物化石

甘肃临夏地区中新世哺乳动物化石引起学术界的重视。经过考察、发掘,哪现了大量的化石标本。由于发表的文章多为单篇,较分散,笔者收集整理,对材料进行了研究,认为甘肃临夏地区在近直余年来是全国发现中新世材料最多的地区,且有极高的研究价值,填补了我国中新世哺乳动物化石中的部分空白。     

恐龙骨骼化石保护材料研究

自贡恐龙化石埋藏丰富、分布广泛、保存完整,具有非常重要的科学价值.为更好保护已出土恐龙化石,本文以甲基丙烯酸甲酯和丙烯酸丁酯为主要原料,采用核壳聚合制备聚合物乳液,与纳米SiO2共混后应用于恐龙化石保护.结果表明:乳液分散均匀、涂层热稳定性高、涂膜附着力好(一级);经乳液涂覆的恐龙化石具有优良耐紫外线、耐酸碱性和耐水性;同时,涂膜透明性好,不影响恐龙化石外观;纳米复合乳液有望在化石保护中广泛应用.     

Application of computed tomography in paleoanthropological research

Hominin fossils are the most important materials for exploring questions about human origins and evolution. Because human fossils are very rare, it is impossible to use highly destructive techniques in order to study their morphology. Traditional analyses can only rely on the information gained from the study of the external morphology of specimens, and these approaches limited the study of human evolution. The application of computed tomography (CT) has facilitated major developments in paleoanthropology. To date, few studies on Chinese hominin fossils have used CT scanning methodology, but this is rapidly changing. In order to better understand the application of CT methodology in paleoanthropology, we review the applications of CT scanning on hominin fossils throughout the world. Studies examined include virtual fossil reconstruction, the use of endocasts to elucidate brain morphology, biomechanical analyses of bone distribution, imaging of mummies and research on early human health, and skeletal and dental microanatomical research.     

Pleistocene Homo sapiens from Middle Awash,Ethiopia

The origin of anatomically modern Homo sapiens and the fate of Neanderthals have been fundamental questions in human evolutionary studies for over a century. A key barrier to the resolution of these questions has been the lack of substantial and accurately dated African hominid fossils from between 100,000 and 300,000 years ago. Here we describe fossilized hominid crania from Herto, Middle Awash, Ethiopia, that fill this gap and provide crucial evidence on the location, timing and contextual circumstances of the emergence of Homo sapiens. Radioisotopically dated to between 160,000 and 154,000 years ago, these new fossils predate classic Neanderthals and lack their derived features. The Herto hominids are morphologically and chronologically intermediate between archaic African fossils and later anatomically modern Late Pleistocene humans. They therefore represent the probable immediate ancestors of anatomically modern humans. Their anatomy and antiquity constitute strong evidence of modern-human emergence in Africa.