[Neoselachii] Compagno, 1977 - modern sharks and rays see Cohort Neoselachii Compagno, 1977 Order Heterodontiformes Compagno, 1973 [monotypic] - bullhead sharks Family Heterodontidae Gray, 1851 [monotypic] - bullhead and horn sharks Genus Heterodontus Blainville, 1816 Heterodontus mexicanus Taylor & Castro-Aguirre, 1972 - Mexican hornshark