The Cretaceous -LRB- -LSB- pronkrᵻˈteɪʃəs -RSB- , -RRB- is a geologic period and system that spans 79 million years from the end of the Jurassic Period million years ago -LRB- Mya -RRB- to the beginning of the Paleogene Period Mya .
The Cretaceous is a Paleogene extinction event .