Cretaceous Period

Many of the most famous dinosaurs, such as Tyrannosaurus and Triceratops, first appeared in the Cretaceous (kruh-TAY-shus) Period, which lasted from 144 to 65 million years ago. During this last part of the Mesozoic Era, the first flowering plants evolved, along with bees, wasps, and other insects.

Pronunciation: kruh-TAY-shus
What It Is: a geologic period of time that spanned the last 79 million years of the Mesozoic Era
When: 144 to 65 million years ago
Name Origin: from the Latin Creta, meaning "chalk"
Significance: The Cretaceous Period marked the end of the line for all non-avian dinosaurs. However, fossil evidence indicates that many groups of animals and plants that exist on Earth today evolved during this period.

Image credits: © AMNH/R.Barber.