2.23: Cenozoic Era
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The Cenozoic is commonly referred to as the Age of Mammals. The Cenozoic Era began with the mass extinction event associated with the K/T Boundary (discussed above). Highlights of the Cenozoic Era include:
• Dominant large animals: Mammals. Mammals diversified, gradually replacing the niches held by dinosaurs wiped out by the K/T extinction.
• Mountain building continued, especially around the Pacific Ocean; the Himalayan Mountains, the Alps, and mountain ranges throughout southern Eurasia begin to form. The Rocky Mountains and Cordilleran Ranges in western North America continued to form.
• Lots of erosion of existing mountains fed sediments to coastal plains and ocean margin basins.
• The youngest Tejas Sequence began to accumulated in the early Cenozoic Era and continues to the present day, forming the Atlantic and Gulf Coast regions.
|The Cenozoic Era is generally divided into two (or three) periods:|
|Tertiary||Paleogene||66 million to 23 million years ago|
|Neogene||23 million to 2.6 million years ago|
|Quaternary||2.6 million years ago to the present|
The older name, Tertiary Period, in now subdivided into two periods: Paleogene Period and Neogene Period.
The periods of the Cenozoic Era are also subdivided into time periods called epochs.