نتایج جستجو برای: pliocene
تعداد نتایج: 2942 فیلتر نتایج به سال:
The late Pliocene, ~3.3–3.0 Ma, is the most recent interval of sustained global warmth in the geologic past. This window is the focus of climate reconstruction efforts by the U.S. Geological Survey’s Pliocene Research, Interpretation, and Synoptic Mapping (PRISM) Data/Model Cooperative, and may provide a useful climate analog for the coming century. Reconstructions of past surface ocean conditi...
A late Pliocene – early Pleistocene, 2.9–2.0Ma, diatom record from the Antarctic Geological Drilling Program (ANDRILL) MIS drillcore AND-1B is presented. This core, recovered from beneath the Ross Ice Shelf south of Ross Island, comprises multiple diatomaceous-sediment units deposited during interglacial periods with open water over the core site. These represent interglacial phases of orbitall...
The Atacama Desert has experienced a long and protracted period of hyperaridity that has resulted in what may be the most unusual biome on Earth, but the duration of this aridity is poorly constrained. We reconstructed aspects of the fl uvial and geochemical history of this region using integrated landscape features (alluvial fans, hillslope soils, soil chemistry, river profi les) in the southe...
The mid-Pliocene warm period is a recent warm geological period that shares similarities with predictions of future climate. It is generally held the mid-Pliocene Atlantic Meridional Overturning Circulation must have been stronger, to explain a weak Atlantic meridional δ(13)C gradient and large northern high-latitude warming. However, climate models do not simulate such stronger Atlantic Meridi...
The mid-Piacenzian climate represents the most geologically recent interval of long-term average warmth relative to the last million years, and shares similarities with the climate projected for the end of the 21(st) century. As such, it represents a natural experiment from which we can gain insight into potential climate change impacts, enabling more informed policy decisions for mitigation an...
The mid-Pliocene was a global warm period, preceding the onset of Quaternary glaciations. Here we use cosmogenic nuclide dating to show that a fossiliferous terrestrial deposit that includes subfossil trees and the northern-most evidence of Pliocene ice wedge casts in Canada's High Arctic (Ellesmere Island, Nunavut) was deposited during the mid-Pliocene warm period. The age estimates correspond...
We tested different hypotheses related to the origin and evolution of the endemic Iberian fishes Chondrostoma arcasii and Chondrostoma macrolepidotus from northern and central regions of the Iberian Peninsula. We evaluated the monophyly of the populations within each species and sought to determine if diversification of the populations coincided in time with the formation of the Iberian drainag...
The first well defined Pliocene mammalian faunas in the Czech Republic – found at localities Měňany 3 and Vitošov – are reported herein. Pilot samples from the localities have yielded an assemblage of at least 23 taxa of small mammals (Lipotyphla, Chiroptera, Lagomorpha, and Rodentia). The key taxa Mimomys hassiacus, M. cf. gracilis (an advanced form), Baranomys, and Germanomys in the assemblag...
Climate predictions produced by numerical climate models, often referred to as general circulation models (GCMs), suggest that by the end of the twenty-first century global mean annual surface air temperatures will increase by 1.1-6.4 degrees C. Trace gas records from ice cores indicate that atmospheric concentrations of CO2 are already higher than at any time during the last 650000 years. In t...
The Late Miocene-Early Pliocene Hyargas-Nuur formation in Western Mongolia yielded a rich fauna of birds which contributes significantly to our knowledge of the Neogene avian diversity in Asia. A study of new fossil remains, collected during the last 20 years, and a revision of several previously described taxa are presented in this paper. Cygnus pristinus is shown to be clearly separable from ...
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