NOSTOLEPIS MATUKHINI VALIUKEVIČIUS, 1994

(FIG. 4Q–T; TABLE 1)

Nostolepis matukhini Valiukevičius 1994, 157, 158, figs. 68.2–68.5, 69.1, 69.2, pl. 20.9, 20.10.

Type material — Holotype LIGG 30-1627; Uryum beds, Taimyr, Russia (Lower Devonian, Lochkovian).

Referred specimens —Scales assigned to this species occur at levels 527.25’ (160.7 m) and 562.6’ (170.1 m) and include UCR 5443-2, -5 (level 562.6’= 170.1 m): Roberts Mountains Formation.

Description —Scales with a distinctively ornamented crown, with 5–7 strong, smooth subparallel or radial ridges that bifurcate towards the anterior margin. Posterolateral edges of the crown are straight and smooth, converging at a slightly obtuse angle at the posterior corner (Fig. 4Q–T). The base is moderately convex, and the neck has only small pore openings. Scarcity of material precluded thin sectioning to examine histology.

Comparison —The crown ornament on N. matukhini scales is very distinctive, with all ridges bifurcating along the anterior margin, a feature not shown in any other nostolepid-type scales.