نتایج جستجو برای: cenozoic

تعداد نتایج: 2977  

2002
F. FLORINDO G. S. WILSON A. P. ROBERTS L. SAGNOTTI K. L. VEROSUB

The Cape Roberts Project was successfully completed in the austral spring of 1999 with drilling of the 939.42-m CRP-3 drillhole, located 2-km west of the CRP-2/2A drillhole. The CRP-3 core comprises a 790-m Cenozoic (glacio-) marine sequence separated from underlying Devonian basement rocks by a c. 30-mthick dolerite conglomerate of undetermined age. Here, we present the results of a palaeomagn...

Journal: :Systematic biology 1999
J Alroy

Paleontologists long have argued that the most important evolutionary radiation of mammals occurred during the early Cenozoic, if not that all eutherians originated from a single common post-Cretaceous ancestor. Nonetheless, several recent molecular analyses claim to show that because several interordinal splits occurred during the Cretaceous, a major therian radiation was then underway. This c...

2012
Sindia M. Sosdian Caroline H. Lear Ethan L. Grossman Aaron O’Dea Yair Rosenthal

[1] Records of seawater chemistry help constrain temporal variations in geochemical processes that impact the global carbon cycle and climate through Earth’s history. Here we reconstruct Cenozoic seawater Sr/Ca (Sr/Casw) using fossil Conus and turritellid gastropod Sr/Ca. Combined with an oxygen isotope paleotemperature record from the same samples, the gastropod record suggests that Sr/Casw wa...

2016
Nicholas D Pyenson Geerat J Vermeij

Large consumers have ecological influence disproportionate to their abundance, although this influence in food webs depends directly on productivity. Evolutionary patterns at geologic timescales inform expectations about the relationship between consumers and productivity, but it is very difficult to track productivity through time with direct, quantitative measures. Based on previous work that...

2006
Alexandra V. Turchyn Daniel P. Schrag

We report new data on oxygen isotopes in marine sulfate (d18OSO4), measured in marine barite (BaSO4), over the Cenozoic. The d18OSO4 varies by 6x over the Cenozoic, with major peaks 3, 15, 30 and 55 Ma. The d 18OSO4 does not co-vary with the d 34SSO4, emphasizing that different processes control the oxygen and sulfur isotopic composition of sulfate. This indicates that temporal changes in the d...

2009
Jan Backman Kathryn Moran

The Arctic Coring Expedition (ACEX) proved to be one of the most transformational missions in almost 40 year of scientific ocean drilling. ACEX recovered the first Cenozoic sedimentary sequence from the Arctic Ocean and extended earlier piston core records from ∼1.5 Ma back to ∼56 Ma. The results have had a major impact in paleoceanography even though the recovered sediments represents only 29%...

Journal: :Memorias do Instituto Oswaldo Cruz 2000
C B Cox

The marsupial and placental mammals originated at a time when the pattern of geographical barriers (oceans, shallow seas and mountains) was very different from that of today, and climates were warmer. The sequence of changes in these barriers, and their effects on the dispersal of the mammal families and on the faunas of mammals in the different continents, are reviewed. The mammal fauna of Sou...

Journal: :Science 2003
David Jablonski Kaustuv Roy James W Valentine Rebecca M Price Philip S Anderson

Up to 50% of the increase in marine animal biodiversity through the Cenozoic at the genus level has been attributed to a sampling bias termed "the Pull of the Recent," the extension of stratigraphic ranges of fossil taxa by the relatively complete sampling of the Recent biota. However, 906 of 958 living genera and subgenera of bivalve mollusks having a fossil record occur in the Pliocene or Ple...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2006
Gene Hunt Kaustuv Roy

Causes of macroevolutionary trends in body size, such as Cope's Rule, the tendency of body size to increase over time, remain poorly understood. We used size measurements from Cenozoic populations of the ostracode genus Poseidonamicus, in conjunction with phylogeny and paleotemperature estimates, to show that climatic cooling leads to significant increases in body size, both overall and within ...

2018
Junsheng Nie Alex Pullen Carmala N Garzione Wenbin Peng Zhao Wang

Theories of late Cenozoic climate cooling assume that central Asian aridification and high dust accumulation rates in the Chinese Loess Plateau and the North Pacific Ocean are genetically related. On the basis of detailed sediment provenance analysis, we show that high dust accumulation rates in the Chinese Loess Plateau and the North Pacific Ocean during the late Miocene-Pliocene were mainly c...

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