Diplocaulidae

The Diplocaulidae ("double cauls") is an extinctfamily of "nectridean" tetrapodomorphs that arose during the Late Carboniferous and died out in the Late Permian. They are distinguished by the presence of strange, horn-like protrusions jutting out from the rear of their skulls; in some genera said protrusions gave their heads an almost boomerang-like outline.