It includes the bullhead sharks (genus Heterodontus), and several extinct genera.

The earliest known members of the group are from the Early Jurassic (Toarcian), around 175 million years ago.

Several extinct genera are known from the Jurassic, with all except Paracestracion only known from isolated teeth.

Paracestracion exhibits notable anatomical differences from Heterodontus and is placed in its own family, Paracestracionidae within the order.

The oldest known members of Heterodontus appeared during the Late Jurassic.