Late Silurian to earliest Devonian vertebrate biostratigraphy of the Birch Creek II section, Roberts Mountains, Nevada, U. S. A. Author Burrow, Carole Jan Author Murphy, Michael Author Turner, Susan text PaleoBios 2023 2023-06-06 40 1975 1 32 http://dx.doi.org/10.5070/p940454153 journal article 10.5070/P940454153 0031-0298 10913559 58312615-0833-432E-BF5D-3DFFBF361AAA 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.