dewlap vs lower jaw

dewlap

noun
  • The sagging flesh on the throat of an elderly human. 

  • The pendulous skin under the neck of an ox, or a similar feature on any other animal. 

lower jaw

noun
  • The part of the face below the mouth; the jaw. 

  • Specifically, the bone therein; the mandible of humans and other vertebrates that, with the cranium, composes the skull. 

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