cretaceous period is a noun meaning "from 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants". It carries one recorded sense.
from 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants
Definitions, synonyms and semantic relations for cretaceous period come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.