Original citation: Slater, T.S., Ashbrook, Kate and Kriwet, J. (2020) Evolutionary relationships among bullhead (: Heterodontiformes). Papers in Palaeontology. ISSN 2056-2802 (In Press) https://doi.org/10.1111/ALL.14168

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1 2 3 1 Evolutionary relationships among bullhead sharks (Chondrichthyes: 4 5 2 Heterodontiformes) 6 7 8 3 9 10 4 by TIFFANY S. SLATER1,2*, KATE ASHBROOK1, and JÜRGEN KRIWET3 11 12 5 13 14 1 15 6 School of Science and the Environment, University of Worcester, Worcester WR2 6AJ, UK; 16 17 7 e-mail: [email protected] 18 19 8 2Current address: School of Biological, Earth and Environmental Sciences, University 20 21 22 9 College Cork, Distillery Fields, North Mall, Cork T23 TK30, Ireland; e-mail: 23 24 10 [email protected] 25 26 11 3 University of Vienna, Department of Palaeontology, Althanstraße 14, Wien 1090, Austria; 27 28 12 e-mail: [email protected] 29 30 31 13 32 33 14 *Corresponding author 34 35 15 36 37 38 16 Abstract: The evolution of modern sharks, skates and rays (Elasmobranchii) is largely 39 40 17 enigmatic due to their possession of a labile cartilaginous skeleton; consequently, taxonomic 41 42 18 assignment often depends on isolated teeth. Bullhead sharks (Heterodontiformes) are a group 43 44 45 19 of basal neoselachians, thus their remains and relationships are integral to understanding 46 47 20 elasmobranch evolution. Here we fully describe †Paracestracion danieli – a bullhead 48 49 21 from the Late plattenkalks of Eichstätt, Germany (150–154 Ma) – for its inclusion in 50 51 22 cladistic analyses (employing parsimonious principles) using morphological characters from 52 53 54 23 complete †Paracestracion and Heterodontus fossil specimens as well as extant forms of the 55 56 24 latter. Results confirm the presence of two separate monophyletic clades within 57 58 25 Heterodontiformes based on predominantly non-dental characters, which show a strong 59 60

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1 2 3 26 divergence in body morphology between †Paracestracion and Heterodontus (the latter 4 5 27 possessing a first dorsal