This is most evident from the climate that existed at the beginning of the Cenozoic. When the era started, there were no glaciers or ice caps on the Earth. Both Polar Regions were too warm for those to exist (17). Today the average Arctic temperature is -14 °C (7 °F) which is warm compared to the average Antarctic temperature which is a stunning -50 °C (-58 °F) (18). When the era started, both regions had average temperatures that were above freezing (19).
