نتایج جستجو برای: paleocene
تعداد نتایج: 1189 فیلتر نتایج به سال:
Temperatures in tropical regions are estimated to have increased by 3° to 5°C, compared with Late Paleocene values, during the Paleocene-Eocene Thermal Maximum (PETM, 56.3 million years ago) event. We investigated the tropical forest response to this rapid warming by evaluating the palynological record of three stratigraphic sections in eastern Colombia and western Venezuela. We observed a rapi...
—The late Paleocene-early Eocene transition was characterized by a long period of global warming that culminated with the highest temperatures of the Cenozoic. This interval is associated with a significant increase in plant diversity in temperate latitudes. However, data from tropical regions remain largely unknown. The record of pollen and spore diversity across the late Paleocene to the earl...
Earliest Paleocene Purgatorius often is regarded as the geologically oldest primate, but it has been known only from fossilized dentitions since it was first described half a century ago. The dentition of Purgatorius is more primitive than those of all known living and fossil primates, leading some researchers to suggest that it lies near the ancestry of all other primates; however, others have...
Dramatic warming and upheaval of the carbon system at the end of the Paleocene Epoch have been linked to massive dissociation of sedimentary methane hydrate. However, testing the Paleocene-Eocene thermal maximum hydrate dissociation hypothesis has been hindered by the inability of available proxy records to resolve the initial sequence of events. The cause of the Paleocene-Eocene thermal maximu...
The Paleocene-Eocene transition in North American land-mammal faunas is well documented on the south side of Polecat Bench and in surrounding badlands of northwestern Wyoming. Here a rich fossil record is known from a stratigraphic section with an established geomagnetic polarity time scale and mediumto high-resolution carbon and oxygen isotope records. The Paleocene-Eocene carbon isotope excur...
The Nanxiong Basin (Guangdong Province, China) preserves the most complete Asian stratigraphic record of the Cretaceous-Paleogene (K/Pg) boundary extinction and the subsequent Paleocene mammalian radiation. Despite extensive study, the precise placement of the K/Pg boundary in the Nanxiong Basin sequence has been controversial, and the timing of subsequent mammalian turnover is poorly constrain...
available online at http://meteoritics.org 1 © Meteoritical Society, 2004. Printed in USA. Is the transition impact to post-impact rock complete? Some remarks based on XRF scanning, electron-microprobe, and thin section analyses of the Yaxcopoil-1 core in the Chicxulub crater J. SMIT,1* S. VAN DER GAAST,2 and W. LUSTENHOUWER1 1Faculty of Earth and Life Sciences, Vrije Universiteit, de Boelaan 1...
A profound faunal reorganization occurred near the Paleocene/Eocene boundary, when several groups of mammals abruptly appeared on the Holarctic continents. To test the hypothesis that this event featured the dispersal of groups from Asia to North America and Europe, we used isotope stratigraphy, magnetostratigraphy, and quantitative biochronology to constrain the relative age of important Asian...
Food web recovery from mass extinction is poorly understood. We analyzed insect-feeding damage on 14,999 angiosperm leaves from 14 latest Cretaceous, Paleocene, and early Eocene sites in the western interior United States. Most Paleocene floras have low richness of plants and of insect damage. However, a low-diversity 64.4-million-year-old flora from southeastern Montana shows extremely high in...
Analyses of leaf megafossil and dispersed leaf cuticle assemblages indicate that major ecologic disruption and high rates of extinction occurred in plant communities at the Cretaceous-Tertiary boundary in the Raton Basin. In diversity increase, the early Paleocene vegetational sequence mimics normal short-term ecologic succession, but on a far longer time scale. No difference can be detected be...
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