The Cenozoic or Cainozoicera (sometimes Caenozoic Era) is the most recent of the four classic geological eras. It covers the 64 million years since the extinction event at the end of the Cretaceous that marked the demise of the last dinosaurs and the end of the Mesozoic Era. The Cenozoic era is still ongoing.
The Cenozoic is the age of mammals. During the Cenozoic, mammals diverged from a few small, simple, generalized forms into a diverse collection of terrestrial, marine, and flying animals. Flowering plants and birds also evolved substantially in the Cenozoic.
In the late Cenozoic, the Cascade Range of volcanoes extended from southern British Columbia to N California, and represented a new volcanic arc superimposed on older structures.
The animal life of the Cenozoic was dominated by mammals, which were most numerous in the Tertiaryperiod and declined, with the exception of a few specialized types, in the Quaternaryperiod.
Cenozoic land mammals were never as large as the Mesozoicdinosaurs, but many were larger than today's mammals, and included beavers that grew to lengths of more than 7 ft (2 m), sloths as large as elephants, and birds up to 7 ft (2 m) in height.