What use are these items?

molten claws, mursaat tokens, mahgo claws, jade mandible, seared ribcage

All collector items. Certain vendors exchange them for armor parts or weapons and off hand items.

I can't seem to find the collectors for each of the items...anyone know where they're?

their not implemented yet.

I think (in the update info) it's been stated that they are going to be implemented. (read the sorrows/grenth update info again.)

If I remember right, doesn`t one of the collectors in the Desert take Jade Mandibles.

he added jade mads.
+there is a collector for murs tokens already. (you can search for it in this forum).

*I was only referring to the fire island monster items.

ok thx

there is a collector for jade mandibles near the portal between salt flats and diviners assent in the desert.