The Cenozoic Era

The Cenozoic, meaning “new life,” is known as the age of mammals because it was in this era that mammals became a dominant and significant life form, including human ancestors. Birds also flourished in the open niches left by the dinosaur’s demise. Most of the Cenozoic has been relatively warm, with the main exception being the ice age that started about 2.558 million years ago and (despite recent warming) continues today. Tectonic shifts in the west caused volcanism but eventually changed the long-standing subduction zone into a transform boundary.