Scientific papers and news reports about new fossils so regularly come with estimates of age that it’s easy forget how hard-won such data can be.I asked John Hawks, a biologist at the University of Wisconsin and one of the heads of the Rising Star expedition, to talk me through the various available methods—and why they have been difficult to apply to the latest finds.
Over time, volcanoes dotting the island spewed magma that cooled and turned to igneous rock, forming steep mountains.
Rainwater flowed down the mountains, and, as that runoff reached the Mahaulepu Valley on the island’s southeast coast, it encountered fossilized sand dunes, where, through a process called dissolution, a network of caves was formed.
As temperatures increased in the transition between the Pleistocene and Holocene eras, the glaciers melted and the oceans rose, turning big islands into small islands and shrinking animals’ habitats. Angel Soto-Centeno of the American Museum of Natural History and David Steadman, a University of Florida ornithologist, set out to unravel this story.
If extinctions were driven by climate change, they would expect to see radiocarbon-dated fossils of extinct bats from the era known as the Pleistocene-Holocene Transition, and paleoclimate evidence should clearly show changes in available habitat — like the submergence of caves.
The Mladeč samples date to around 31,000 years ago, reports Eva Maria Wild from the VERA (Vienna Environmental Research Accelerator) Laboratory at University of Vienna, where the radiocarbon dating has been performed.
Ideal conditions within an ancient cave system are revealing a rich history that reaches back to a time before humans settled the island and extends to the present day By ANDREW LAWLER Friday, April 03, 2015 Some six million years ago, in the middle of the North Pacific Ocean, volcanic activity bubbling up from deep beneath the Earth’s crust formed Kauai, the most ancient of Hawaii’s major islands.
The dating results document that these samples are as old as we thought they should be, agree Maria Teschler-Nicola from the Natural History Museum in Vienna and Erik Trinkaus from the Washington University in St.
Louis, the two anthropologists involved in this study.
Without good radiocarbon-dating evidence, it’s been difficult to peg just when these die-offs occurred, which makes it harder to pin down what caused them. This challenges previous research that suggests natural climate changes were a culprit.
Earth 25,000 years ago was a cooler place, with huge amounts of water locked up in glaciers.
They excavated bat wing bones from a cave on Great Abaco, an island in the Bahamas, and dated them along with more than 2,000 bat fossils from 20 different sites in the Caribbean.