Fossils show puzzling lack of evolution during past climate changes

Thousands of fossils from the La Brea tar pits in California show no signs of mammals and birds evolving in response to shifting temperatures over the past 50,000 years

​Thousands of fossils from the La Brea tar pits in California show no signs of mammals and birds evolving in response to shifting temperatures over the past 50,000 years Thousands of fossils from the La Brea tar pits in California show no signs of mammals and birds evolving in response to shifting temperatures over the past 50,000 years