E. lunensis is known from a nearly complete skull of about 11 cm in length.

It is known from a single 90 millimeter long skull, discovered in Texas in 1908.

Fedexia is known from a single skull found in Pittsburgh, Pennsylvania.

It is only known from an incomplete skull.

It is known from a well preserved skull.

It is known from a nearly complete skull and fragments of pachyosteosclerotic (thick) ribs.

D. elegans is currently known from a single skull about 112 millimetres in length.

It is known from a single skull found in southern Peru.

It is currently known from a partially crushed skull.

It is known from a single incomplete skull from Kenya.