نتایج جستجو برای: lower eocene

تعداد نتایج: 695634  

2002
Daniel B. Kirk-Davidoff Daniel P. Schrag James G. Anderson

[1] Past climates, such as the Eocene (55 38 Ma), experienced dramatically warmer polar winters. Global climate models run with Eocene-like boundary conditions have under-predicted polar temperatures, a discrepancy which has stimulated a recent hypothesis that polar stratospheric clouds may have been important. We propose that such clouds form in response to higher CO2 via changes in stratosphe...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2001
P Wilf C C Labandeira K R Johnson P D Coley A D Cutter

Insect damage on fossil leaves from the Central Rocky Mountains, United States, documents the response of herbivores to changing regional climates and vegetation during the late Paleocene (humid, warm temperate to subtropical, predominantly deciduous), early Eocene (humid subtropical, mixed deciduous and evergreen), and middle Eocene (seasonally dry, subtropical, mixed deciduous and thick-leave...

2001
Matthew Huber Lisa Cirbus Sloan

For the first time, a coupled general circulation model with interactive and dynamical atmospheric, oceanic, and sea-ice components, is used to simulate an Eocene (∼50 Ma) “greenhouse”climate. We introduce efficient ocean spin-up methods for coupled paleoclimate modeling. Sea surface temperatures (SSTs) and salinities evolve unconstrained, producing the first proxy data-independent estimates fo...

Journal: :Geodiversitas 2022

Rodents from the Eocene locality of Cos (Tarn-et-Garonne, Quercy, France). Comparison with rodents localities transition lower Eocene/middle Eocene. This article describes new fauna Quercy) whose primates were first studied and published (Godinot et al. 2021) Among these poorly diversified rodent assemblage, smallest species is assigned to Eogliravus wildi. All Hartenberger, 1971 are redescribe...

2013
Laurent Marivaux Anusha Ramdarshan El Mabrouk Essid Wissem Marzougui Hayet Khayati Ammar Renaud Lebrun Bernard Marandat Gilles Merzeraud Rodolphe Tabuce Monique Vianey-Liaud

BACKGROUND Molecular clock estimates of crown strepsirhine origins generally advocate an ancient antiquity for Malagasy lemuriforms and Afro-Asian lorisiforms, near the onset of the Tertiary but most often extending back to the Late Cretaceous. Despite their inferred early origin, the subsequent evolutionary histories of both groups (except for the Malagasy aye-aye lineage) exhibit a vacuum of ...

2016
Matthew Huber Henk Brinkhuis Catherine E. Stickley Kristofer Döös Appy Sluijs Jeroen Warnaar Stephen A. Schellenberg Graham L. Williams

[1] Near the Eocene's close ($34 million years ago), the climate system underwent one of the largest shifts in Earth's history: Antarctic terrestrial ice sheets suddenly grew and ocean productivity patterns changed. Previous studies conjectured that poleward penetration of warm, subtropical currents, the East Australian Current (EAC) in particular, caused Eocene Antarctic warmth. Late Eocene op...

2002
Andrea L. Dutton Kyger C Lohmann William J. Zinsmeister

[1] Abundant and well-preserved marine macrofossils on Seymour Island, Antarctica, provide a valuable resource to establish paleoenvironmental conditions at high southern latitudes during the warm Paleogene. Stable isotope, minor element, and Sr/Sr compositions have been measured for the aragonite bivalve Cucullaea from the Eocene La Meseta Formation. The Sr/Sr stratigraphy suggests an early to...

2003
A. Hope Leonel Silveira Lobo Sternberg

Note: MAT—mean annual temperature; CMM—cold month mean temperature; NLR—nearest living relative analogy; CLAMP—climate–leaf analysis multivariate program. ABSTRACT The exquisite preservation of fossilized Metasequoia trees that grew near 808N latitude during the middle Eocene (ca. 45 Ma) in Nunavut, Canada, allowed for dD and d18O analyses of cellulose, techniques previously restricted to wood ...

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