نتایج جستجو برای: lower paleozoic
تعداد نتایج: 693427 فیلتر نتایج به سال:
Because many survivors of mass extinctions do not participate in postrecovery diversifications, and therefore fall into a pattern that can be termed "Dead Clade Walking" (DCW), the effects of mass extinctions extend beyond the losses observed during the event itself. Analyses at two taxonomic levels provide a first-order test of the prevalence of DCWs by using simple and very conservative opera...
The phylogenetic relationships between the different groups of Paleozoic gnathostomes are still debated, mainly because of incomplete datasets on Paleozoic jawed vertebrate fossils and ontogeny of some modern taxa. This issue is illustrated by the condition of the glossopharyngeal nerve relative to the parachordal plate, the otic capsules and the metotic fissure in gnathostomes. Two main condit...
The Mesozoic lacustrine revolution (MLR) represents a major evolutionary event in the continental realm (Cohen 2003 ). The decline in taxic diversity at the family level in lacustrine environments that took place during the late Paleozoic–Middle Triassic was reversed later in the Mesozoic, with diversifi cation seeming to have continued to the Quaternary, although potential biases may have affe...
The Ordos Basin contains abundant coal resources in the Upper Paleozoic strata. They are shallowly buried or exposed periphery of basin, forming recoverable mines and coalbed methane resources. For deeply seams however, due to complex changes difficult mining, less attention was paid before. In recent years, with exploitation tight gas related source rocks, a large amount drilling seismic data ...
The late Paleozoic deglaciation is the vegetated Earth's only recorded icehouse-to-greenhouse transition, yet the climate dynamics remain enigmatic. By using the stable isotopic compositions of soil-formed minerals, fossil-plant matter, and shallow-water brachiopods, we estimated atmospheric partial pressure of carbon dioxide (pCO2) and tropical marine surface temperatures during this climate t...
Abstract The West Kalabsha (WKAL) area is a western extreme exploratory of the Faghur Basin in Western Desert Egypt. study four wells (WKAL; A-1 X, K-1 P-1X, and C-1 X), interpreted with twenty seismic lines, shows that dissected by series normal faults an irregular, E–W strike direction. general trend throw toward south–southeast. most prospective for hydrocarbon (HC) migration north (upthrown...
In the wake of the end-Permian mass extinction, the Early Triassic (~251.9 to 247 million years ago) is portrayed as an environmentally unstable interval characterized by several biotic crises and heavily depauperate marine benthic ecosystems. We describe a new fossil assemblage-the Paris Biota-from the earliest Spathian (middle Olenekian, ~250.6 million years ago) of the Bear Lake area, southe...
Several recent analyses of paleomagnetic data support the concept of Pangea, an assemblage of most of the world’s continents that was mobile in terms of large-scale internal deformation and with respect to paleolatitude. The main feature of internal deformation involved the transformation from a Pangea B–type configuration in the late Paleozoic, with northwestern South America adjacent to easte...
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