Maxilla

In dinosaurs, the maxilla (plural: maxillae) is the posterior, and usually largest, tooth-bearing bone of the upper jaw. Anteriorly, it connects to the premaxilla and often contributes to the border of the external naris. Over most of its length, the maxilla forms the ventral limits of the antorbital fenestra as well as the depression surrounding this opening, the antorbital fossa, which is deeply recessed within the maxilla. In derived theropods, the maxilla may feature two smaller, additional openings, the promaxillary fenestra and the maxillary fenestra. At its posterior end, the maxilla articulates with the jugal and the lacrimal.