Whizbang Dustyboots
Gnometown Hero
I'm guessing the Isle of Dread -- which is crazy big, once you start counting hexes -- could probably handle one pack of T. Rexes. Still, that would be enough. I imagine their territory would be picked clean pretty quickly, requiring them to move in search of new prey periodically. The human tribes would likely have the migration timeline down to a near-science, as it would make hunting beyond the wall untenable while the pack was in the area.