.. there's something wrong with his teeth.. they totally do not need to be that long and stick out everywhere.
also, when doing dinos, lizards, and such you should model and rig the lower jaw and the skull separately, so they're both rigid pieces, and that the lower jaw really opens where it should, and so you don't get the tiny inside of the mouth. they do need their throat mesh, as well as two triangles that are in each corner of the mouth, to look like a bit of skin that does stretch when roaring or otherwise keeping the mouth open