In terms of where those little tusks/fangs were seated in the skull we are talking about the caudal body of the premaxilla. The bone itself is adjusted so that the teeth sit comfortably into the notch, or diastema, that is formed by this adaptation of the bone. The maxilla itself joins the premaxilla in a way that forms the caudal wall of the diastema where the tusks are situated. The skull is actually, despite the images shared showing the skull earlier in the week, not as exaggerated as we have assumed. Reconstructed in three dimensions, this formation in the skull that houses the tusks is really little more than a narrowing of the solid oral cavity in the area where the teeth are pronounced upward into the mouth. See below:
|From The Dinosauria|
Weishampel, D. B. and Witmer, L. M. (1990). Heterodontosauridae. in Weishampel, D. B., Dodson, P., & Osmólska, H. (Eds.). Pgs. 486-497. The Dinosauria. Univ of California Press.