نتایج جستجو برای: cambrian
تعداد نتایج: 2615 فیلتر نتایج به سال:
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...
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...
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...
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 ...
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...
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