نتایج جستجو برای: cambrian

تعداد نتایج: 2615  

2017
James D. Schiffbauer John Warren Huntley David A. Fike Matthew Jarrell Jeffrey Jay M. Gregg Kevin L. Shelton

Several positive carbon isotope excursions in Lower Paleozoic rocks, including the prominent Upper Cambrian Steptoean Positive Carbon Isotope Excursion (SPICE), are thought to reflect intermittent perturbations in the hydrosphere-biosphere system. Models explaining these secular changes are abundant, but the synchronicity and regional variation of the isotope signals are not well understood. Ex...

Journal: :Zootaxa 2014
I Wesley Gapp Bruce S Lieberman

The Olenelloidea are a superfamily of early Cambrian trilobites, which have been the subject of several phylogenetic analyses and also used to address macroevolutionary questions regarding the nature and timing of the Cambrian radiation. The Sekwi Formation of the Mackenzie Mountains, Northwest Territories, Canada, has yielded numerous species from this clade, and here we present new informatio...

Journal: :Science 2011
Douglas H Erwin Marc Laflamme Sarah M Tweedt Erik A Sperling Davide Pisani Kevin J Peterson

Diverse bilaterian clades emerged apparently within a few million years during the early Cambrian, and various environmental, developmental, and ecological causes have been proposed to explain this abrupt appearance. A compilation of the patterns of fossil and molecular diversification, comparative developmental data, and information on ecological feeding strategies indicate that the major anim...

Journal: :Geological Magazine 1951

Journal: :Economic Geology 1913

Journal: :Proceedings of the United States National Museum 1905

Journal: :International Geology Review 2022

Detrital zircon populations of the South Qiangtang terrane (SQT) provide vital information for reconstructing Tethyan evolution Tibetan Plateau but are obscured by undefined affiliation detrital samples and superimposition multiple tectonothermal events. We outlined SQT based on geological mapping collated Cambrian-Triassic to investigate representative populations. Although diachronous strata ...

Journal: :Geological Society of America Bulletin 2022

The Ediacaran−Cambrian boundary strata in the Great Basin of southwestern United States record biological, geochemical, and tectonic change during transformative interval Earth history which metazoans diversified. Here, we integrate new compiled chemostratigraphic, paleontological, sedimentological, stratigraphic data sets from Death Valley region, White-Inyo Ranges, Esmeralda County Nevada Cal...

Journal: :Geological Society of America Bulletin 1899

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