“…Several examples are given to show the morphological differences in cross-section. Examples are: (b), Lophosteus [ 24 ]; (c), Nostolepis [ 23 , 32 ], (d), Diplacanthus [ 10 ]; (e) ischnacanthid ([ 23 , 32 ]; (f), Ischyodus [ 41 ]; (g) Chimaera [ 41 ]; (h), Callorhinchus [ 16 ]; (i), Orthacanthus [ 42 , 43 ]; (j), Ctenacanthus [ 16 , 22 ]; (k), Squalus [ 15 , 16 ]; (l), Heterodontus [ 15 ]; (m), Etmopterus [ 15 ]; and, (n), Oxynotus [ 15 ]. The question mark indicates extinct taxa that bear fin spines but currently have no histological data and the null sign indicates the loss of dermal fin spines in crown osteichthyans.…”