aurochs vs plains buffalo

aurochs

noun
  • The European bison (Bison bonasus, or Europæus). 

  • An extinct European mammal, Bos primigenius, the ancestor of domestic cattle. 

plains buffalo

noun
  • Bison bison bison; Synonym of plains bison 

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