long in the tooth vs septuagenarian

long in the tooth

adj

  • Old; aged. 

septuagenarian

adj

  • Of or related to seventysomethings. 

noun

  • Synonym of seventysomething: a person between 70 and 79 years old. 

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