Figure 3 in The histology and affinities of sinacanthid fishes: primitive gnathostomes from the Silurian of China

Figure 3. Hypothesis of phylogenetic relationships of lower vertebrates based upon the cladograms of Donoghue et al. (2000) for the lower vertebrates and Coates & Sequeira (2001b) for the chondrichthyans. Taxa underlined (e.g. Eriptychius) are known to have possessed globular calcified cartilage, whilst those in bold and asterisked (e.g. chondrichthyans*) possessed spines composed from single units. The distribution of these two characters, coupled with the growth model suggested in the main text for sinacanthid spines, suggest that they occupy a position close to the chondrichthyan node; either as a highly derived component of the gnathostome stem-group (crownward of the placoderms) (dashed line 1), or plesiomorphic or basal crown-group chondrichthyans (dashed line 2).