Algal fossils from a late precambrian, hypersaline lagoon

Organically preserved algal microfossils from the Ringwood evaporite deposit in the Gillen Member of the Bitter Springs Formation (late Precambrian of central Australia) are of small size, low diversity, and probable prokaryotic affinities. These rather primitive characteristics appear to reflect the stressful conditions that prevailed in a periodically stagnant, hypersaline lagoon. This assemblage (especially in comparison with the much more diverse assemblages preserved in the Loves Creek Member of the same formation) illustrates the potential utility of Proterozoic microbiotas for basin analysis and local stratigraphic correlation and demonstrates the need to base evolutionary considerations and Precambrian intercontinental biostratigraphy on biotas that inhabited less restricted environments.     

Alga-like fossils from the early precambrian of South Africa

Micropaleontological studies of carbonaceouis chert from the Fig Tree Series of South Africa (> 3.1 x 10(9) years old) revealed the presence of spheroidal microfossils, here designated Archaeosphaeroides barbertonensis, interpreted as probably representing the remnants of unicellular alga-like organisms. The presumed photosynthetic nature of these primitive microorganisms seems corroborated by organic geochemical and carbon isotopic studies of the Fig Tree organic matter, and is consistent with the geologically and mineralogically indicated Early Precambrian environment. These alga-like spheroids, together with a bacterium-like organism previously described from the Fig Tree chert, are the oldest fossil orgisms now known.     

Trace fossils from the athabasca oil sands, alberta, Canada

A diverse and well-preserved ichnofossil suite has been identified from surface exposures of the middle and upper parts of the Lower Cretaceous McMurray Formation. The suite, consisting of representatives of at least ten ichnogenera, is one of the few clues to the original biotic component of the deposit. The distribution and abundance of these biogenic structures present strong evidence that the deep channel complex in which the sediments were deposited was closely associated with a nearby marine shoreline.     

Zircon ages of felsic volcanic rocks in the upper precambrian of the blue ridge, appalachian mountains

Five Zirconi samples from Pennsylvania, Virginia, and North Carolina yield discordant uranium-lead ages which suggest an original age of 820 million years and an episodic lead loss at 240 million years. The indicated age of lead loss is interpreted as the age of movement of the Blue Ridge thrust sheet.     

Allerod--younger dryas lake temperatures from midge fossils in atlantic Canada

Remains of freshwater midges are abundant in lake sediments, and their species distributions are closely related to the surface-water temperature of lakes; their distributions thus provide a powerful tool for paleoclimatology. The distribution of species in a core from Splan Pond in Atlantic Canada indicates that there were abrupt transitions in late-glacial temperatures between warm and cold states. The transitions are correlative with the well-known warm Aller?d and cold Younger Dryas events in Europe. These data thus confirm the inference from palynological data that these events affected regions on both sides of the Atlantic.     

Microorganisms from the late precambrian of the grand canyon, Arizona

An assemblage of cellularly well-preserved, filamentous and spheroidal plant microfossils has been detected in a cherty pisolite bed of the late Precambrian Chuar Group from the eastern Grand Canyon of the Colorado River. This newly discovered microflora, probably among the youngest Precambrian biological communities now known, appears to be of both evolutionary and biostratigraphic significance.     

Chitinozoans from the late precambrian chuar group of the grand canyon, Arizona

Carbonaceous shales of the late Precambrian Chuar Group of the Grand Canyon, Arizona, contain abundant and well-preserved chitinozoans. The occurrence of these distinctive, tear- and flask-shaped microfossils, the oldest chitinozoans now known and the first to be reported from the Precambrian, seems to suggest that heterotrophic protists (or primitive metaozoans) were extant at least as early as about 750 +/- 100 million years ago.     

Microorganisms three billion years old from the precambrian of South Africa

A minute, bacterium-like, rod-shaped organism, Eobacterium isolatum, has been found organically and structurally preserved in black chert from the Fig Tree Series (3.1 x 10(9) years old) of South Africa. Filamentous organic structures of probable biological origin, and complex alkanes, which apparently contain small amounts of the isoprenoid hydrocarbons pristane and phytane, are also indigenous to this Early Precambrian sediment. These organic remnants comprise the oldest known evidence of biological organization in the geologic record.     

History of atmospheric lead deposition since 12,370 (14)C yr BP from a peat bog, jura mountains, switzerland

A continuous record of atmospheric lead since 12,370 carbon-14 years before the present (14C yr BP) is preserved in a Swiss peat bog. Enhanced fluxes caused by climate changes reached their maxima 10, 590 (14)C yr BP (Younger Dryas) and 8230 (14)C yr BP. Soil erosion caused by forest clearing and agricultural tillage increased lead deposition after 5320 (14)C yr BP. Increasing lead/scandium and decreasing lead-206/lead-207 beginning 3000 (14)C yr BP indicate the beginning of lead pollution from mining and smelting, and anthropogenic sources have dominated lead emissions ever since. The greatest lead flux (15.7 milligrams per square meter per year in A.D. 1979) was 1570 times the natural, background value (0.01 milligram per square meter per year from 8030 to 5320 (14)C yr BP).     

Carbon isotope composition of carbonaceous matter from the precambrian of the witwatersrand system

Polymerized hydrocarbons occurring in the gold-uranium conglomerates of the Witwatersrand System (South Africa) show deltaC(13) values between -22.4 and -32.8 per mille, their isotopic composition thus falling into the range of sedimentary organic carbon. Accordingly, organic derivation of the material seems very probable. This conclusion is consistent with a model of the existence of organic evolution and biologic activity in times certainly older than 2.15 x 10(9) years.     

Evidence for lignin-like constituents in early silurian (llandoverian) plant fossils

Chemical evidence is presented with previously reported morphological features for banded-tube cell types in the earliest known plant fossils associated with stream-deposited sediments. Phenolic aldehydes (p-hydroxybenzaldehyde, vanillin) and aromatic compounds from pyrolysis (2-methoxy-4-hydroxybenzaldehyde, methylsyringaldehyde) derived from cellular remains are interpreted as evidence for lignin or lignin-like degradation products. The presence of parallel-aligned banded tubes, with annular to spiral thickenings and occasional end walls, in conjunction with lignin-like constituents fulfill most of the morphological and chemical criteria for cell types that could have functioned as water-conducting cells.     

Microfossils in conophyton from the soviet union and their bearing on precambrian biostratigraphy

Silicified specimens of the Vendian (late Precambrian) "index fossil" Conophyton gaubitza from South Kazakstan contain a diverse assemblage of well-preserved cyanophytic and apparently eukaryotic algae, the first stromatolitic microbiota to be reported from the Soviet Union. Unlike the stromatolites in which they occur, the microorganisms that apparently built this form of Conophyton did not become extinct at the end of the Precambrian.     

黑龙江完达山地区狍子冬季生境选择

2007和2008年11—12月在黑龙江省完达山东部林区的五泡林场和河口林场对狍子冬季生境选择进行了研究。通过在野外布设110条样线,每条样线长5km,样线间间距2km的方法收集生境数据,利用资源选择指数(RSI)和资源选择函数(RSF)分析狍子冬季生境选择。结果表明:狍子偏向于选择针阔混交林(资源选择指数Si=0.37)和阔叶林(Si=0.19)、隐蔽度在35%～70%(Si=0.46)、郁闭度在35%～70%(Si=0.61)、盖度为10%～20%(Si=0.27)、坡度25°(Si=0.18)、乔木密度0.06株/m2(Si=0.59)、乔木胸径15cm(Si=0.66)、人为干扰距离500m(Si=0.12,Si=0.30)、中坡位(Si=0.14)、阳坡(Si=0.44)的生境;狍子对灌丛(Si=-0.05)、郁闭度35%(Si=-0.03)、盖度10%(Si=0.04)的生境表现出随机选择;不喜欢选择针叶混交林(Si=-0.56),不选择农田生境(Si=-1.00)。狍子在完达山东部林区的生境资源选择函数为logit(P)=-11.17+0.71×隐蔽度+3.24×坡向+0.59×食物丰富度-0.62×干扰距离-0.25×乔木胸径+0.01×灌木密度+0.07×坡位,狍子对生境的选择概率为P=elogit(P)/(1+elogit(P))。     

长白山区野生木本观赏树木调查

依据野外调查结果和有关文献资料,运用统计和比较的方法,评价和分析了长白山区野生观赏树木种类的多样性、观赏特性,生长类型的多样性,调查了在不同景观带野生观赏树木垂直分布的种类和数量及珍稀濒危野生观赏树木的现状和园林用途.调查发现长白山区有野生观赏树木39科、92属、202种.根据观赏特性划分,有观形树木18科、26属、51种,观叶树木 23科、34属、59种,观花树木23科、50属、103种,观果树木29科、51属、105种,观干枝树木8科、8属、21种;按生长类型划分,有乔木25科、44属、96种,灌木21科、46属、94种,藤本6科、9属、12种.野生观赏树木在夏绿阔叶蒙古栎林带里有36科、76属、156种,红松针阔混交林带里有38科、89属、188种,针叶林带里有25科、53属、86种,岳桦林带里有10科、20属、23种,高山苔原带里有7科、10属、13种,高山荒漠带里有3科、4属、7种.国家级野生珍稀濒危观赏树木13科、17属、19种,省级15科、20属、25种.这些野生观赏树木可以在园林绿化中作为行道树或庭荫树栽培,也可做园景树在园林中孤植或片植,用作垂直绿化和制作桩景.本文还就长白山区野生观赏树木资源的保护、利用与引种驯化提出了具体建议.     

Stratigraphy of the wisconsin range, horlick mountains, antarctica

The Wisconsin Range consists of a basement complex of granitic and metamorphic rocks unconformably overlain by about 550 meters of Upper Paleozoic sedimentary rocks. The base of the Upper Paleozoic succession is composed of the Buckeye formation, a tillite, which varies in thickness from 80 to more than 140 meters. Overlying the Buckeye formation are the Weaver and Queen Maud formations, with a combined thickness of about 455 meters, characterized by a prolific Glossopteris flora, indicative of a Permian age.     

Prehistoric rock avalanches in the olympic mountains, washington

Rock avalanches blocked streams in the Olympic Mountains southwest of Puget Sound during the past few thousand years. Limiting radiocarbon ages indicated that three or four of six avalanches occurred from 1000 to 1300 years ago or shortly thereafter. Most of the dates were from the outer preserved rings of trees drowned behind avalanche dams. These three or four avalanches may be coeval not only with one another but also with abrupt tectonic deformation in western Washington. No rock avalanches in the Olympic Mountains are known to have resulted from storms or earthquakes during the past century. The avalanches strengthen the case that a large prehistoric earthquake occurred in the Puget Sound region.     

The initial domestication of goats (Capra hircus) in the Zagros mountains 10,000 years ago

Initial goat domestication is documented in the highlands of western Iran at 10,000 calibrated calendar years ago. Metrical analyses of patterns of sexual dimorphism in modern wild goat skeletons (Capra hircus aegagrus) allow sex-specific age curves to be computed for archaeofaunal assemblages. A distinct shift to selective harvesting of subadult males marks initial human management and the transition from hunting to herding of the species. Direct accelerator mass spectrometry radiocarbon dates on skeletal elements provide a tight temporal context for the transition.     

Small bilaterian fossils from 40 to 55 million years before the cambrian

Ten phosphatized specimens of a small (<180 micrometers) animal displaying clear bilaterian features have been recovered from the Doushantuo Formation, China, dating from 40 to 55 million years before the Cambrian. Seen in sections, this animal (Vernanimalcula guizhouena gen. et sp. nov.) had paired coeloms extending the length of the gut; paired external pits that could be sense organs; bilateral, anterior-posterior organization; a ventrally directed anterior mouth with thick walled pharynx; and a triploblastic structure. The structural complexity is that of an adult rather than a larval form. These fossils provide the first evidence confirming the phylogenetic inference that Bilateria arose well before the Cambrian.