نتایج جستجو برای: lower eocene

تعداد نتایج: 695634  

Journal: :Science 2006
Andreas Mulch Stephan A Graham C Page Chamberlain

We determine paleoelevation of the Sierra Nevada, California, by tracking the effect of topography on precipitation, as recorded in hydrogen isotopes of kaolinite exposed in gold-bearing river deposits from the Eocene Yuba River. The data, compared with the modern isotopic composition of precipitation, show that about 40 to 50 million years ago the Sierra Nevada stood tall (>/=2200 meters), a r...

2015
Yunfa Chen Steven R. Manchester William Oki Wong

Deviacer guangxiensis Chen & Manchester sp. nov. is described based on asymmetric samaras from the Oligocene Ningming Formation in Guangxi, South China, representing the first documentation of Deviacer fossils in Asia. The Oligocene species, with relatively large fruits, represents the youngest record of the genus so far known; all other records are from the Paleocene and Eocene, or late Eocene...

Journal: :Sedimentary Geology 2021

The Eocene continental sequence investigated in this study belongs to the Salta Group; it was deposited an intracontinental rift, Basin (NW Argentina) that evolved from Lower Cretaceous middle Paleogene. Group contains Maíz Gordo and Lumbrera Fms, spans Paleocene-early Eocene, shows excellent exposures region of Valles Calchaquíes. This research is focused on facies Fm, which correspond early E...

Journal: :Current Biology 2014
Bo Wang Jes Rust Michael S. Engel Jacek Szwedo Suryendu Dutta André Nel Yong Fan Fanwei Meng Gongle Shi Edmund A. Jarzembowski Torsten Wappler Frauke Stebner Yan Fang Limi Mao Daran Zheng Haichun Zhang

Paleogene arthropod biotas have proved important for tracing the faunal turnover and intercontinental faunal interchange driven by climatic warming and geodynamic events [1-5]. Despite the large number of Paleogene fossil arthropods in Europe and North America [5-8], little is known about the typical Asian (Laurasia-originated) arthropod biota. Here, we report a unique amber biota (50-53 millio...

شب افروز, روح اله , محبوبی, اسداله, موسوی حرمی, رضا,

The Sachun Formation (Paleocene-Lower Eocene) is mainly composed of carbonates and evaporates that were deposited in shallow-marine evaporitic mudflat environments. The Sachun Formation in the study area has been divided into three units including: lower evaporate; middle bioclastic limestone and upper evaporate. It is mainly composed of diagenetic gypsum, which originated from dehydration of a...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2001
M S Engel

Advanced eusociality sometimes is given credit for the ecological success of termites, ants, some wasps, and some bees. Comprehensive study of bees fossilized in Baltic amber has revealed an unsuspected middle Eocene (ca. 45 million years ago) diversity of eusocial bee lineages. Advanced eusociality arose once in the bees with significant post-Eocene losses in diversity, leaving today only two ...

2018
Giuseppe Marramà Giorgio Carnevale

Fishes of the family Clupeidae are extremely abundant in the Eocene fossiliferous limestone of Monte Bolca representing the most common group from this celebrated locality. A new clupeid from the Pesciara site, Eoalosa janvieri gen. et sp. nov., is described. The new taxon exhibits a unique combination of characters supporting its recognition as a new genus and species of clupeid fish that is t...

2006
D. Soudry C. R. Glenn Y. Nathan I. Segal D. VonderHaar

The evolution of Tethyan phosphogenesis during the Cretaceous–Eocene is examined to try to explain fluctuations of phosphogenesis through time, and whether or not they reflect long-term changes in ocean circulation or in continental weathering. Twenty-seven time-stratigraphic phosphate levels in various Tethyan sites, covering a time span of about 90 Myr from the Hauterivian to the Eocene, were...

2016
Andrzej Pisera Renata Manconi Peter A Siver Alexander P Wolfe

The freshwater sponge species Ephydatia cf. facunda Weltner, 1895 (Spongillida, Spongillidae) is reported for the first time as a fossil from middle Eocene lake sediments of the Giraffe kimberlite maar in northern Canada. The sponge is represented by birotule gemmuloscleres as well as oxea megascleres. Today, E. facunda inhabits warm-water bodies, so its presence in the Giraffe locality provide...

Journal: :Science 2002
Gabriel J Bowen William C Clyde Paul L Koch Suyin Ting John Alroy Takehisa Tsubamoto Yuanqing Wang Yuan Wang

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...

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