Observing the Cheek Bones of Panoplosaurus mirus

This is the case for Panoplosaurus mirus, in which not only do the dental rows seem strongly inset (they are not) but lateral expansion of the nasopharyngeal sinuses (forming extreme loops; Witmer & Ridgely, 2008) causes the lateral margins of the skull to expand beyond the lateral extend of the mandible at the same part. This has led to a subjective impression that there was a distinctive, broad cheeky overhang. The main culprit is the presence of thin, vertically oriented bones in the “buccal cavity” of the skull, in this species and in others. If there was no “cheek,” what is this thing doing in the skull? What is it attached to? And precisely, what is its relation to extra-oral tissues surrounding the jaw? Interestingly, these ossicles support a full buccal tissue that expands from the skull to the mandible. This homologue tissue exists in mammals and a few (very few) birds, namely parrots (which have a unique muscle, m.pseudomasseter).