Figure 3. Acanthodian fin spines and scapulocoracoid. A-C in Acanthodian fauna from the Early Devonian (Emsian) of Death Valley, California

Figure 3. Acanthodian fin spines and scapulocoracoid. A-C, Bryantonchus peracutus: A, B complete spine FMNH-PF14564; C, proximal end of spine FMNH-PF14568. D, E, Machaeracanthus sp.: D, incomplete spine FMNH-PF14573, lateral view; E, abraded spine FMNH-PF14574, dorsoventrally compressed. F-H, acanthodian indet. scapulocoracoid: F, counterpart FMNH-PF14575; G, part FMNH-PF14576; H, outline sketch. Abbreviations: IEB, insertion-exsertion boundary; k/w, worn keel or wing; plac, placoderm plate; le, leading edge; te, trailing edge; teg, trailing edge groove. Scale bars=0.5 mm in A, C–E, 0.1 mm in B, F–H.