نتایج جستجو برای: permian system

تعداد نتایج: 2233955  

2009
LAURA K. SÄILÄ

European Russia has been the source of many procolophonoid taxa from both the Permian and Triassic, and a Permian or− igin for the procolophonoid family Procolophonidae has been based on the Russian taxon Microphon exiguus. Recently, this taxon was reclassified as a seymouriamorph and, in its place, the taxa Nyctiphruretus, Suchonosaurus, and Kinelia from the Middle and Upper Permian of Russia ...

Journal: :PLoS ONE 2008
Jörg Fröbisch

The end-Permian biotic crisis (~252.5 Ma) represents the most severe extinction event in Earth's history. This paper investigates diversity patterns in Anomodontia, an extinct group of therapsid synapsids ('mammal-like reptiles'), through time and in particular across this event. As herbivores and the dominant terrestrial tetrapods of their time, anomodonts play a central role in assessing the ...

Journal: :Science 2004
Jonathan L Payne Daniel J Lehrmann Jiayong Wei Michael J Orchard Daniel P Schrag Andrew H Knoll

High-resolution carbon isotope measurements of multiple stratigraphic sections in south China demonstrate that the pronounced carbon isotopic excursion at the Permian-Triassic boundary was not an isolated event but the first in a series of large fluctuations that continued throughout the Early Triassic before ending abruptly early in the Middle Triassic. The unusual behavior of the carbon cycle...

2004
E. S. KRULL

Carbon isotopic studies from marine organic matter of the Permian-Triassic Maitai Group, New Zealand, reveal a significant 5Corg shift toward more negative values within the Little Ben Sandstone Formation. These isotopic data chemostratigraphically define the previously debated position of the Permian-Triassic boundary in the Maitai Group. The Permian-Triassic record of the Maitai Group is also...

Journal: :Science 2005
Peter D Ward Jennifer Botha Roger Buick Michiel O De Kock Douglas H Erwin Geoffrey H Garrison Joseph L Kirschvink Roger Smith

The Karoo basin of South Africa exposes a succession of Upper Permian to Lower Triassic terrestrial strata containing abundant terrestrial vertebrate fossils. Paleomagnetic/magnetostratigraphic and carbon-isotope data allow sections to be correlated across the basin. With this stratigraphy, the vertebrate fossil data show a gradual extinction in the Upper Permian punctuated by an enhanced extin...

2006
Wayne R. Wright

Morrowan-age units in the Permian Basin appear to show a “second-order” transgression from siliciclastic fluvial-deltaic to shallow-marine and subsequently to carbonate deposition. In general, Morrowan-age siliciclastics dominate deposition in the west of the Permian Basin, while carbonate deposition dominates in the east. The predominance of carbonate facies in the east is due to a lack of sil...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1981
R M Garrels A Lerman

A reservoir model of a Recent steady-state sedimentary system in which the reduced sulfur and oxidized sulfur reservoirs were coupled with the oxidized carbon and reduced carbon reservoirs was constructed. The time curve of the sulfur isotope ratios of the sedimentary sulfate reservoir was used to drive the model back to the beginning of Cambrian time (600 million years ago), producing the rese...

2009
Ian Metcalfe Yukio Isozaki

The end-Permian mass extinction is now robustly dated at 252.6 ± 0.2 Ma (U–Pb) and the Permian–Triassic (P–T) GSSP level is dated by interpolation at 252.5 Ma. An isotopic geochronological timescale for the Late Permian–Early Triassic, based on recent accurate high-precision U–Pb single zircon dating of volcanic ashes, together with calibrated conodont zonation schemes, is presented. The durati...

2015
Massimo Bernardi Hendrik Klein Fabio Massimo Petti Martín D. Ezcurra David Carrier

We present a holistic approach to the study of early archosauriform evolution by integrating body and track records. The ichnological record supports a Late Permian-Early Triassic radiation of archosauriforms not well documented by skeletal material, and new footprints from the Upper Permian of the southern Alps (Italy) provide evidence for a diversity not yet sampled by body fossils. The integ...

2005
G. J. RETALLACK A. H. JAHREN N. D. SHELDON R. CHAKRABARTI C. A. METZGER R. M. H. SMITH

The Permian ended with the largest of known mass extinctions in the history of life. This signal event has been difficult to recognize in Antarctic non-marine rocks, because the boundary with the Triassic is defined by marine fossils at a stratotype section in China. Late Permian leaves (Glossopteris) and roots Vertebraria), and Early Triassic leaves (Dicroidium) and vertebrates (Lystrosaurus) ...

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