Fossils show puzzling lack of evolution during last Ice Age peak

Studies of tens of thousands of fossils from the La Brea tar pits in California have found no clear evidence of any of the species evolving in response to falling temperatures as ice sheets spread across the continent, or to the later warming when the glacial period ended.

“They’re not fluctuating with climate change like so many biologists believe that everything must do,” says Donald Prothero at California State Polytechnic University in Pomona. “They’re static, despite obvious evidence of climate change at 20,000 years ago.”