Definitions

1. adjective

relating to or denoting a geological time interval of the late Paleozoic era, roughly from 320 to 250 million years ago, characterized by the rise of the first modern land plants and the development of amphibians.

“During the cryptozoic period, the Earth’s climate began to change significantly.”

2. noun

a geological time interval of the late Paleozoic era.

“The cryptozoic is often referred to as the time of the first modern land plants.”