earless seal vs pinniped

earless seal

noun
  • Any of the seals in the taxonomic family Phocidae characterized by lacking external ear flaps; true seals. 

pinniped

noun
  • Any of various large marine mammals belonging to the superfamily (formerly considered a suborder) Pinnipedia comprising walruses, eared seals and earless seals. 

adj
  • Pertaining to or similar to such a mammal. 

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