Figure 12 in The characters of Palaeozoic jawed vertebrates

Figure 12. Alternative phylogenetic placements for problematic acanthodian-like taxa and their implications in light of two characters discussed in the text and assumptions of acanthodian monophyly. A, one of the hypotheses implied by placing only Kathemacanthus and Seretolepis on the chondrichthyan stem, independent of other acanthodians. B, equally parsimonious placement of Kathemacanthus and Seretolepis on osteichthyan stem. C, consensus tree showing that resolution of Kathemacanthus and Seretolepis to the chondrichthyan stem collapses if all other acanthodians are placed on the osteichthyan stem (areal scale growth is plesiomorphic). D–F, improvements to parsimony score if some or all acanthodians are moved to the chondrichthyan stem (restoration of areal scale growth as a chondrichthyan synapomorphy). D, hypothesis in which all acanthodians are stem chondrichthyans, but paraphyletic. E, hypothesis in which all acanthodians are stem chondrichthyans but monophyletic. F, hypothesis in which taxa with areally growing scales are stem chondrichthyans, whereas the remaining (assumed monophyletic) Acanthodii are stem osteichthyans. Ambiguities in character state distributions based on a soft polytomy may entail different lengths depending on their resolution. Note that loss of areal scale growth in Acanthodii and Osteichthyes reflects transitions to different, not identical, states and must therefore be treated as separate events. Asterisk indicates values derived from resolving stem chondrichthyan polytomy as a paraphylum with respect to the crown.