The Antarctic Dry Valleys are among the most extreme environments anywhere, so dry and windswept and barren that they are thought to be the closest analog to the surface of Mars.
So imagine the surprise when, several years ago, Adam R. Lewis, a glacial geologist, and a colleague found what Dr. Lewis described as “freeze-dried fossils sticking out of the ground.”
Those fossils now form the basis for further understanding the global cooling that occurred during the mid-Miocene epoch, some 14 million years ago. In a paper in The Proceedings of the National Academy of Sciences, Dr. Lewis, now at North Dakota State University, and colleagues show that the Antarctic cooled by at least 14 degrees Fahrenheit over about 200,000 years.
The fossils were found at sites that had been small lakes, in sediments that were 14.07 million years old. So that must have been a period of “wet glaciation,” when it was warm enough for glaciers to melt .
Then, at sediments that are 13.85 million years old, there are no fossils at all, Dr. Lewis said. By then, conditions must have been so cold that the glaciers did not melt at all .
Previously, most knowledge of mid-Miocene cooling came from marine records. “But nobody knew particularly what was Antarctica’s role,” he added. “That’s where the fossils come in.”

HENRY FOUNTAIN