Data from: Evolutionary relationships among bullhead sharks (Chondrichthyes: Heterodontiformes)

The evolution of modern sharks, skates and rays (Elasmobranchii) is
largely enigmatic due to their possession of a labile cartilaginous
skeleton; consequently, taxonomic assignment often depends on isolated
teeth. Bullhead sharks (Heterodontiformes) are a group of basal
neoselachians, thus their remains and relationships are integral to
understanding elasmobranch evolution. Here we fully describe
†Paracestracion danieli – a bullhead shark from the Late Jurassic
plattenkalks of Eichstätt, Germany (150–154 Ma) – for its inclusion in
cladistic analyses (employing parsimonious principles) using morphological
characters from complete †Paracestracion and Heterodontus fossil specimens
as well as extant forms of the latter. Results confirm the presence of two
separate monophyletic clades within Heterodontiformes based on
predominantly non-dental characters, which show a strong divergence in
body morphology between †Paracestracion and Heterodontus (the latter
possessing a first dorsal fin and pectoral fins that are placed more
anterior and pelvic fins that are placed more posterior). This study
emphasizes the importance of including non-dental features in
heterodontiform systematics (as compared to the use of dental characters
alone) and supports the erection of the family †Paracestracionidae.
Further, phylogenetic analysis of molecular data from five extant species
suggests that crown heterodontiforms arose from a diversification event
42.58 Ma off the west coast of the Americas.