Thrinacodus ferox ( Turner, 1982 )

Ginter, Michał & Złotnik, Michał, 2019, Mississippian chondrichthyan fishes from the area of Krzeszowice, southern Poland, Acta Palaeontologica Polonica 64 (3), pp. 549-564 : 552

Thrinacodus ferox ( Turner, 1982)

Fig. 2 .

Material.— Ten teeth: five (ZPAL P. IV/301, 302, 321–323) from the upper Viséan, Czerna, sample Cz-1 and five MWGUW/Ps/1/212–214, MWGUW/Ps/13/1, 18) from the upper Tournaisian, Czatkowice, sample A.

Remarks.— Most of the teeth of Thrinacodus ferox found at Czerna and Czatkowice are classical asymmetrical forms with the distal cusp much larger than the other two Fig. 2B, C, E, F ). However, in sample Cz-1 there also occurs a tooth ( Fig. 2A ) somewhat similar to Thrinacodus dziki ( Ginter et al. 2015) , with the size difference between the delicate, sigmoidal cusps less conspicuous. In sample A from Czatkowice a minute, almost symmetrical tooth was found ( Fig. 2D ), closely resembling that illustrated by Turner (1982: fig. 3A). Such teeth most probably represent anterior, parasymphyseal tooth families.

The teeth strongly vary in size: the length of the base in the smallest is about 0.3 mm, but in the largest it reaches 4 mm. The largest teeth are abraded and their cusps are broken.

Stratigraphic and geographic range.— Cosmopolitan in the Tournaisian, rare occurrences in the uppermost Famennian and the Viséan.

Figures

Fig. 2. Teeth of chondrichthyan fish Thrinacodus ferox (Turner, 1982) from the upper Viséan of Czerna, Poland (A, B) and the Tournaisian of Czatkowice, Poland (C–F). A. ZPAL P. IV/301, in labial (A1) and oral (A2) views. B. ZPAL P. IV/302 in oral view. C. MWGUW/Ps/13/1 in lingual (C1), labial (C2), oral (C3), and lateral (C4) views. D. MWGUW/Ps/1/212, subsymmetrical, parasymphysial (?) tooth in lingual (D1), labial (D2), and lateral (D3) views. E. MWGUW/Ps/1/214 in lateral view. F. MWGUW/Ps/1/213 in basal view.