Use Elmers to attach loose parts or teeth.Sometimes you may need to use some strips of tape to hold parts while glue is drying.Sometimes a rubber band can be used around the nasal area to keep those bones from spreading.
Elmers can be thinned with water and used as a satin sealer for the skull as well.Epoxies and many other glues will yellow,Elmers will not,plus it is cheap,available and easy to clean up.
I normally use Future floor finish and water,mixed 50/50 as a skull sealer and it is a great finish for antlers as well.It really brings out the color on antlers.Mixed right,it should give the antlers a mild sheen.If you get too much sheen on antlers,wipe them down with some Windex on a rag.Some leather workers recommend the same Future mixture as a leather finish after oiling sheaths,holsters etc..It's good stuff and smells nice too.Also non-yellowing.