Third Level; Former Term for Part of the Cenozoic

This page is the CodyCross answer for the clue below from Space Exploration, Group 914, Puzzle 1 (Unpiloted Probes).

Question is: Third Level; Former Term for Part of the Cenozoic

and the answer is: TERTIARY

Word Meaning:

TERTIARY — Of third rank or order; subsequent.

Definitions from Wiktionary.