The Tertiary time period lasted from 65 to 1.8 million
years ago, a time span of 63 million years. The Tertiary Period is the
first part of the Cenozoic Era. The term Tertiary was first used in the
1760s to describe the uppermost of a three part division of the rocks
in the mountains of northern Italy. These Tertiary rocks were defined
based on a particular type of fossil assemblage contained within them.
They are located above the rocks of the Cretaceous
System and below the rocks of the Quaternary