Monospina Valiukevičius, 2003b

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 Monospina Valiukevičius, 2003b

Type and only species: Monospina erecta Valiukevičius, 2003b ; Timan−Pechora region , Olenya−2 borehole, depth 4070.8–4078.3 m; Upper Silurian , Pridoli, Greben’ Regional Stage .

Diagnosis.—Acritolepid acanthodian with small and medium−sized flank scales (<0.5 mm wide) having monospinous crowns, inclined at an angle of 40 ° to the bases which are flat or gently convex; scales lack necks, their pointed cone−shaped posterior crown edge far overhangs the base; two to six subradial short ridges extend back from the anterior edge, occasionally reaching the posterior part of the crown; shortest lateral ridges may converge with the longest ones; three lamellae of superpositional growth in crowns are composed of cellular bone or bone−like tissue which has dense polygonal osteocytes and short connecting processes, but is devoid of vascular canals. The tissues in crown and base of scales merge gradually to each other.