Remember it is only the lower jaw (mandibula) that moves.    From Wordnik.com.  [Stabroek News] Reference

The upper mandibula is much longer than the lower, overhanging it considerably.    From Wordnik.com.  [Expedition into Central Australia] Reference

Illius mandibula.    From Wordnik.com.  [The Youth of Jefferson A Chronicle of College Scrapes at Williamsburg, in Virginia, A.D. 1764] Reference