14: Phanerozoic Eon - Cenozoic Era
- Page ID
- 33590
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Here is the the simplified geologic time scale used in the Geologic Time chapter of this book. The Cenozoic Era is highlighted at the top.
Figure \(\PageIndex{1}\): The geological time scale. (Creative Commons License. This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License; Edited. Original image by Jonathan R. Hendricks.)
The Cenozoic, meaning “new life,” is known as the Age of Mammals because it was during this era that mammals became a dominant group, including human ancestors. Birds, too, flourished through adaptive radiation after the demise of the dinosaurs. Most of the Cenozoic Era has been relatively warm, with the main exception being the ice age that began approximately 2.558 million years ago and continues to this day. The East Coast of North America remained a passive continental margin, whereas in the West, tectonic activity led to volcanism and, eventually, the long-standing subduction zone evolved into a transform boundary.
Figure \(\PageIndex{2}\): Paraceratherium, seen in this reconstruction, was a massive (15-20 ton, 15 foot tall) ancestor of rhinos.