antediluvial vs prehistoric

antediluvial

adj
  • Of or pertaining to a time before Noah's flood. 

  • Antiquated. 

prehistoric

adj
  • Of or relating to the epoch before written record. 

  • Ancient; very old, outdated, etc. 

How often have the words antediluvial and prehistoric occurred in a corpus of books? (source: Google Ngram Viewer )