Undergraduate Bursary Report: Sharks with question marks - impacts of a new fossil on interrelationships of early bullhead sharks
Introduction
Bullhead sharks (Heterodontiformes) represent a monophyletic group that occupies a basal position within modern sharks, rays, and skates (Neoselachii) (Carvalho 1996). Remains of Heterodontiformes are among the oldest in the fossil record for Neoselachii (Kriwet 2008). Three genera are known from the Jurassic as a result of their rapid diversification: Proheterodontus and Paracestracion, which disappear from the fossil record before the Cretaceous, and the extant Heterodontus, which underwent further radiation in the Cretaceous.