FIG. 6. — Machaeracanthus goujeti n in Machaeracanthus goujeti n. sp. (Acanthodii) from the Lower Devonian of Spain and northwest France, with special reference to spine histology

FIG. 6. — Machaeracanthus goujeti n. sp.; Lower Devonian, Iberian Chain. Transverse section of distal part of spine MPZ 2010/955A, juvenile: A, general view; B, C, details of the upper longitudinal ridge. Arrows in C point to distal branches of dentinal tubules. Thin section observed in transmitted ordinary light. Abbreviations: see Material and methods. Scale bars: A, 0.5 mm; B, 0.1 mm; C, 50 μm.