Tchunacanthus, Karatajute-Talimaa & Smith, 2003

Valiukevičius, Juozas & Burrow, Carole J., 2005, Diversity of tissues in acanthodians with Nostolepis-type histological structure, Acta Palaeontologica Polonica 50 (3), pp. 635-649 : 645

Genus Tchunacanthus Karatajūtė− Talimaa and

Smith, 2003 Type and only species: Tchunacanthus obruchevi Karatajūtė− Talimaa and Smith, 2003; Siberia, Irkutsk amphitheatre, Tchuna River, Staroe Balturino outcrop; Lower Silurian , Upper Llandovery , Upper Balturino Subformation .

Diagnosis.—Squamation comprising head, transitional and body scales, and larger tesserae with complicated sculptured crowns and with multilobate outlines; head scales have smooth crowns with concentric growth lines; transitional body scales have crowns folded into longitudinal ridges, formed of separate tubercles; head and transitional scales have deep bases, with funnel−shaped or oblong furrows in centre and surrounding convex bosses subdivided by narrower furrows; base of body scales smaller than crown, diamond−shaped, convex; areal growth characterizes head and transitional scales; body scales have either areal−superpositional or only superpositional growth; canal system absent; crown of cellular mesodentine, with regular, rounded cell spaces, in the inner part of each dentine layer; base contains simple, small, fusiform cell spaces without processes, disposed parallel to distinct growth lines comprising very thin first order, and second−order lines.