Term:

Cretaceous Period
Definition:

A geological time period that is part part of the Mesozoic Era beginning about 144 million years ago and ending about 65 million years ago. See the University of California Museum of Paleontaology at http://www.ucmp.berkeley.edu/index.php for more information.
Notes:

This is the first part of the age of dinosaurs even though some groups of dinosaurs entered the fossil record during this period. In addition, fossils of many insects, modern mammals, birds, and flowering plants appear during this time. See the University of California/Berkely Museum of Paleontology at http://www.ucmp.berkeley.edu/index.php for more information.