نتایج جستجو برای: trace fossil

تعداد نتایج: 91986  

2014
Biplab Bhattacharya Sudipto Banerjee

Rhythmic sandstone-mudstone-coal succession of the Barakar Formation (early Permian) manifests a transition from lower braided-fluvial to upper tide-wave influenced, estuarine setting. Monospecific assemblage of marine trace fossil Chondrites isp. in contemporaneous claystone beds in the upper Barakar succession from two Gondwana basins (namely, the Raniganj Basin and the Talchir Basin) in east...

Journal: :Biology letters 2013
S Blair Hedges

Genetic and fossil data often lack the spatial and temporal precision for tracing the recent biogeographic history of species. Data with finer resolution are needed for studying distributional changes during modern human history. Here, I show that printed wormholes in rare books and artwork are trace fossils of wood-boring species with unusually accurate locations and dates. Analyses of wormhol...

2011
Priska Gisler Mike Michael

In this paper we present a particular history of Limulus polyphemus, the horseshoe crab, as a means of expanding on Haraway’s notion of companion species. Drawing on accounts of the horseshoe crab’s role, on the one hand, in work of the Serological Museum at Rutgers University that spanned the 1940s to the 1970s, and, on the other, in the development of the limulus amebocyte lysate test, we tra...

2003
T. M. Demko

Deposition of marine strata associated with the Lower Pennsylvanian Mary Lee coal zone (Pottsville Formation) was controlled by the allocyclic mechanism of eustatic sea-level change. The vertical stacking of marine, marginal marine, and terrestrial facies indicates that this interval was deposited during a single transgression-regression-transgression cycle. Ravinement surfaces, and associated ...

2013
Daniel J. Field Liliana D’Alba Jakob Vinther Samuel M. Webb William Gearty Matthew D. Shawkey

In birds and feathered non-avian dinosaurs, within-feather pigmentation patterns range from discrete spots and stripes to more subtle patterns, but the latter remain largely unstudied. A ∼55 million year old fossil contour feather with a dark distal tip grading into a lighter base was recovered from the Fur Formation in Denmark. SEM and synchrotron-based trace metal mapping confirmed that this ...

Journal: :Current Biology 2016
Johan Lindgren

Johan Lindgren introduces fossil pigments.

2016
Steven T. Petsch J. J Cole P. Raymond J. E Bauer N. Caraco NINA CARACO JAMES E. BAUER JONATHAN J. COLE STEVEN PETSCH PETER RAYMOND

Recent studies indicate that highly aged material is a major component of organic matter transported by most rivers. However, few studies have used natural C to trace the potential entry of this aged material into modern river food webs. Here we use natural abundance C, C, and deuterium (H) to trace the contribution of aged and contemporary organic matter to an important group of consumers, cru...

Journal: :Biomedical and environmental sciences : BES 1997
A D Lemly

Selenium is a naturally occurring trace element that is nutritionally required in small amounts but it can become toxic at concentrations only twice those required. The narrow margin between beneficial and harmful levels has important implications for human activities that increase the amount of selenium in the environment. Two of these activities, disposal of fossil fuel wastes and agricultura...

Journal: :Journal of hazardous materials 2011
Siyue Li Quanfa Zhang

Water samples were collected for determination of dissolved trace metals in 56 sampling sites throughout the upper Han River, China. Multivariate statistical analyses including correlation analysis, stepwise multiple linear regression models, and principal component and factor analysis (PCA/FA) were employed to examine the land use influences on trace metals, and a receptor model of factor anal...

Journal: :Ecology 2010
Nina Caraco James E Bauer Jonathan J Cole Steven Petsch Peter Raymond

Recent studies indicate that highly aged material is a major component of organic matter transported by most rivers. However, few studies have used natural 14C to trace the potential entry of this aged material into modern river food webs. Here we use natural abundance 14C, 13C, and deuterium (2H) to trace the contribution of aged and contemporary organic matter to an important group of consume...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید