نتایج جستجو برای: fossil

تعداد نتایج: 25461  

2008
Stefano Zibetti Daniele Pierini Gabriel W. Pratt

We study six groups and clusters of galaxies suggested in the literature to be ‘fossil’ systems (i.e. to have luminous diffuse X-ray emission and a magnitude gap of at least 2 mag-R between the first and the second ranked member within half of the virial radius), each having good quality X-ray data and SDSS spectroscopic or photometric coverage out to the virial radius. The poor cluster AWM4 is...

Journal: :Environmental science & technology 2003
Eric Lichtfouse Michel Lichtfouse Anne Jaffrézic

A novel fossil fuel pollution indicator based on the 13C/12C isotopic composition of plants has been designed. This bioindicator is a promising tool for future mapping of the sequestration of fossil fuel CO2 into urban vegetation. Theoretically, plants growing in fossil-fuel-CO2-contaminated areas, such as major cities, industrial centers, and highway borders, should assimilate a mixture of glo...

2018

Acid dissolution is a technique of removing a fossil from the surrounding rock matrix in which it is encased by dissolving that matrix with acid. Fossilized bone, though strong enough to be preserved for thousands or millions of years, is often more delicate than rock. Once a fossil is discovered, scientists must remove the fossil from its surroundings without damaging the fossil itself. Scient...

2008
Jason A. Dunlop

The species-level diversity of fossil Chelicerata is summarized for each order. 1952 valid species of fossil chelicerates are currently recognized, of which 1593 are arachnids. In order of abundance they are: Araneae (979 fossil species), Actinotrichida (283), Eurypterida (241), Scorpiones (111), Xiphosura (96), Trigonotarbida (71), Pseudoscorpiones (38), Phalangiotarbida (30), Opiliones (25), ...

2007
Jerry Bergman

Insects provide a severe challenge for Darwinian evolution. In contrast with the vertebrate fossil record, for example, where only bones are available, evolutionary speculation can run wild, but the exquisite detail of fossil insects has produced virtual silence on this front. A review of the insect fossil record literature reveals a complete lack of evidence for the evolution of insects and ot...

2012
Peter J. Wagner

The fossil record documents over three billion years of evolution. Darwin considered the general succession of morphologies in the fossil record to corroborate the basic idea of evolution by natural selection. However, he also recognized aspects of the fossil record that challenged his ideas. For example, did the sudden appearance of higher taxa reflect a different underlying model of evolution...

2016
Jochen Heinrichs Armin Scheben Julia Bechteler Gaik Ee Lee Alfons Schäfer-Verwimp Lars Hedenäs Hukam Singh Tamás Pócs Paul C. Nascimbene Denilson F. Peralta Matt Renner Alexander R. Schmidt

Cambay amber originates from the warmest period of the Eocene, which is also well known for the appearance of early angiosperm-dominated megathermal forests. The humid climate of these forests may have triggered the evolution of epiphytic lineages of bryophytes; however, early Eocene fossils of bryophytes are rare. Here, we present evidence for lejeuneoid liverworts and pleurocarpous mosses in ...

2018

Acid dissolution is a technique of removing a fossil from the surrounding rock matrix in which it is encased by dissolving that matrix with acid. Fossilized bone, though strong enough to be preserved for thousands or millions of years, is often more delicate than rock. Once a fossil is discovered, scientists must remove the fossil from its surroundings without damaging the fossil itself. Scient...

2016
M. O'Sullivan A. Rap C. L. Reddington D. V. Spracklen M. Gloor W. Buermann

The global terrestrial carbon sink has increased since the start of this century at a time of growing carbon emissions from fossil fuel burning. Here we test the hypothesis that increases in atmospheric aerosols from fossil fuel burning enhanced the diffuse light fraction and the efficiency of plant carbon uptake. Using a combination of models, we estimate that at global scale changes in light ...

2014
Mario dos Reis Philip C. J. Donoghue Ziheng Yang

O'Leary et al. (O'Leary et al. 2013 Science 339, 662-667. (doi:10.1126/science.1229237)) performed a fossil-only dating analysis of mammals, concluding that the ancestor of placentals post-dated the Cretaceous-Palaeogene boundary, contradicting previous palaeontological and molecular studies that placed the ancestor in the Cretaceous. They incorrectly used fossil ages as species divergence time...

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