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February
7, 2007 The
largest climate change in central The overwhelming
majority of
previous climate-change studies on the 400,000-year transition from the
Eocene
to the Oligocene epochs, about 33.5 million years ago, focus on marine
environments, but The study will be
published
online Feb. 7 in the journal Nature
and will appear in the Feb. 8 print edition. "If a temperature
change of
this magnitude occurred today, The
Eocene-to-Oligocene
transition is known in the fossil record as the Grande Coupure, the
"Big
Cut" in French, because it marks a massive extinction of life in both
marine and land environments. Scientists believe the drop in
temperature was
likely due to changes in oceanic currents, MacFadden said. "Fossil mammals are
archives
of ancient information," MacFadden said. "Their teeth are like little
time capsules that allow us to analyze chemicals captured millions of
years ago
within the animals' skeletons." MacFadden said 49 of
the 68
fossil teeth analyzed came from the "A combined analysis
of the
isotope composition of bones and teeth is a new approach to studying
this
boundary in time," said Alessandro Zanazzi, a doctoral student in
geology
at the Donald R. Prothero,
a professor
of geology at Occidental College and an expert on the
Eocene-to-Oligocene
transition, said, "We have long known that there were some dramatic
climatic changes in the earliest Oligocene based on the record of
marine
plankton and isotopes. But we didn't know how much change there was in
degrees,
although the plant changes suggested it was indeed about 15 degrees." Prothero also said
gaps in the
fossil record from
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