Troodon (Currie 1985, 1987 a)

has an elongate, triangular frontal with a long orbital rim (Figs. 1a, 2). A prefrontal has not been identified with certainty in troodontids, although a small, slender bone along the orbital rim of the frontal may be that bone (Currie, 1985). The lacrimal suture encroaches onto the dorsal surface of the frontal, and ends caudally in a wall of bone. The dorsal surface of the frontal is concave in cross-section in the interorbital region, raised on both the midline and the orbital rim. A well defined ridge running from the medial edge of the frontoparietal suture to the deep, pit-like suture for the postorbital marks the anterior boundary of the supratemporal fenestra. As in ornithomimids, NMC 12355 and dromaeosaurids, the frontal provides very little area of bone for muscle attachment within the supratemporal fenestra.