The Diplocaulidae ("double cauls") is an extinct family of "nectridean" tetrapodomorphs that arose during the Late Carboniferous and died out in the Late Permian. [1] 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.
Below is a cladogram modified from Germain (2010):[1]