I often see depictions of the larger therapod dinosaurs such as T Rex, Allosarus and such with the upper teeth extending over the lower lip and exposed. But I have noticed in photos that there seems to be holes running along the upper edge of the lower jaws. I was woundering if they might have had a lower lip that covered the upper teeth when the mouth was fully closed as in modern lizards. I like to draw animals, including dinosaurs, as accruately as possible.
Therapod mouth morphology
