FIGURE 14. Diplacanthus tenuistriatus pectoral fin spines. 1–4 in The diplacanthid fishes (Acanthodii, Diplacanthiformes, Diplacanthidae) from the Middle Devonian of Scotland

FIGURE 14. Diplacanthus tenuistriatus pectoral fin spines. 1–4, spine QM F58024 from Marwick, Orkney: 1, complete spine, dorsal surface; 2, ventral surface of spine; 3, recurved denticles on posterior edges of spine; 4, transverse natural fracture surface of distal part of spine, at point arrowed in (2); 5, NMS G.1901.153.1 from Appat Hill, Caithness; 6, NMS G.1898.163.2 from Birsay, Orkney; 7, NMS G.2014.4.18, from Marwick, Orkney, spine attached to pinnal plate. Scale bars equal 1 cm for 1, 2, 5–7; 1 mm for 3, 4.