Fig. 2 in A microanatomical and histological study of the postcranial dermal skeleton in the Devonian sarcopterygian Eusthenopteron foordi

Fig. 2. Enlarged scales of the sarcopterygian Eusthenopteron foordi Whiteaves, 1881 (MNHM 06−342) from the Late Devonian, Escumenac Bay, Quebec, Canada. A. SEM. Ornamentation of the outer surface of an enlarged dermal scale. B. SEM. Detail of the ornamentation of the outer surface of an enlarged dermal scale. The holes (arrows) correspond with the aperture of vascular canals. C. Vertical section of an enlarged dermal scale in transmitted natural light (C1) and in polarised light (C2). The outer layer composed of superficial parallel−fibered bone covers a discontinuous layer of woven−fibered bone containing primary and secondary osteons. Sharpey's fibres (white arrows) cross the superficial parallel−fibered bone. The basal plate is characterised by the presence of lamellar bone. D. Transmitted natural light (detail of C). The outer layer of an enlarged dermal scale. The secondary osteon is separated by a resorption line (black arrowhead) from the surrounding primary bone where Sharpey's fibres (white arrow) are abundant. Insert: the primary osteon, showing the absence of a resorption line (black arrowheads). Abbreviations: lb, lamellar bone; pf, parallel−fibered bone; post, primary osteon; sost, secondary osteon; vc, vascular canal; wf, woven−fibered bone.