The status of the shark genus Lissodus Brough, 1935, and the position of nominal Lissodus species within the Hybodontoidea (Selachii)

The hybodont form genus Lissodus is taken under revision and found to comprise a number of lineages. Twelve species, stratigraphically extended from the Scythian, Lower Triassic to the Albian, Lower Cretaceous, are retained in Lissodus s.s. Thirteen other species can be included in Lonchidion, here considered as a justified genus, ranging from the Ladinian in the Middle Triassic to the Maastrichtian in the Upper Cretaceous. Of the species previously included in Lissodus, two new genera, Vectiselachos, gen. nov. and Parvodus, gen. nov., are described. Vectiselachos is at present a monotypic genus including a single species from the Lower Cretaceous of southern England. Parvodus comprises three species and is known from the Bathonian, Middle Jurassic to the Valanginian, Lower Cretaceous. Another species is placed in Steinbachodus, expanding the stratigraphical range of the genus from the Rhaetian in the Upper Triassic to the Cenomanian in the Upper Cretaceous. Palaeozoic small-toothed hybodonts are extremely poorly known and alleged Lissodus species fall into two genera, but these are at present kept in open nomenclature. The family Lonchidiidae is considered justified and includes the genera Lissodus, Lonchidion, Vectiselachos, Hylaeobatis and Parvodus