earbone

ear +‎ bone

earbone (plural earbones)

1. (anatomy) Any bone in the ear.
   • 2009 May 15, Edward Rothstein, “Come Meet Your Folks: Warm Blood Is Required”, in New York Times‎:

     This earbone criterion may seem esoteric — until we learn that the evolution of that bone structure is related to the development of a single lower jaw, which in turn, is associated with the fact that mammals, unlike, say, lizards, have differentiated teeth that allow for different kinds of chewing.