Ctenognathodus sp.

Männik, Peep, Miller, C. Giles & Hairapetian, Vachik, 2015, A new early Silurian prioniodontid conodont with three P elements from Iran and associated species, Acta Palaeontologica Polonica 60 (3), pp. 733-746 : 743-745

Ctenognathodus sp.

Fig. 6A–D, F.

Material.— 5 specimens: P 1 element, 1; P 2, 1; S 1–2, 2; S 0?, 1; from a section located about 65 km north-west of Tabas, on the eastern side of the Dahaneh-e-Kolut Gorge in the Derenjal Mountains , East Central Iran; Hill B, uppermost Unit 11 (sample S19). Pterospathodus amorphognathoides lennarti Conodont Zone, Telychian, Llandovery, Silurian .

Description.— P 1 element (Fig. 6A): Carminate with straight, thick blade and basal margin gently curved downwards in lateral view. Denticles broad, discrete and triangular in lateral view with V-shaped gaps between them. Only anterior blade preserved. Narrow, groove-like basal cavity below entire preserved part of blade with narrow inverted zone.

P 2 ? element (Fig. 6F): A single fragment representing base of cusp and part of blade just below it. Posteriorly inclined cusp laterally compressed with sharp anterior and posterior edges and bears a distinct longitudinal ridge in mid-part of the inner lateral face. Other face of cusp smooth and slightly convex.

S 1–2 element (Fig. 6B, C): Digyrate. Cusp with sub-lenticular section that is almost sub-circular in larger specimens but with distinct anterior and weak posterior ridges. Anterior process mainly straight but slightly twisted and curved inwards distally. Anterior process bears up to 5 laterally slightly compressed, discrete widely spaced denticles with sharp

→ Fig. 5. Ozarkodinid conodonts from the late Llandovery part of the Niur Formation of the Derenjal Mountains, East Central Iran, Hill B. A–I, K. Ozarkodina derenjalensis sp. nov. A, E, F. P 1 elements. A. Sinistral element, NHMUK PM X 3640, in outer lateral (A 1), inner lateral (A 2), and lower (A 3) views, sample S12. E. Dextral element, NHMUK PM X 3644, in outer lateral (E 1), inner lateral (E 2), and lower (E 3) views, sample S15. F. Sinistral element, NHMUK PM X 3645, in outer lateral (F 1) and lower (F 2) views, sample S12. B, C, G. P 2 elements. B. Sinistral element, NHMUK PM X 3641, in outer lateral (B 1) and inner lateral (B 2) views, sample S15. C. Dextral element, NHMUK PM X 3642, in inner lateral (C 1) and lower (C 2) views, sample S12. G. Dextral element, NHMUK PM X 3646, in inner lateral (G 1), lower (G 2), and outer lateral (G 3) views, sample S15. D. Dextral M element, NHMUK PM X 3643, in inner lateral (D 1) and lower (D 2) views, sample S15. H. Sinistral S 1–2 element, NHMUK PM X 3647, in inner lateral (H 1) and lower (H 2) views, sample S15. I. Dextral S 3–4 element, NHMUK PM X 3648, in inner lateral (I 1) and lower (I 2) views, sample S15. K. S 0 element, NHMUK PM X 3650, in posterior (K 1) and lower (K 2) views, sample S15. J, L. Ozarkodina sp. nov. (aff. Ozarkodina sp. A Mabillard and Aldridge, 1983). J. Dextral P 1 element, NHMUK PM X 3649, in outer lateral (J 1) and lower (J 2) views, sample S19. L. Dextral P 1 element, NHMUK PM X 3596, in outer lateral (L 1), upper (L 2), inner lateral (L 3), and lower (L 4) views, sample S19. M. Ozarkodina sp. 1 , sinistral P 1 element, NHMUK PM X 3595, in inner lateral (M 1), outer lateral (M

2

), and lower (M

3

) views, sample S15. Scale bars 0.1 mm.

edges, lenticular sections, and wide U-shaped gaps between them. Denticles decrease rapidly in width (?and height) from cusp towards distal end of process. Posterior process almost missing in both specimens available. Basal cavity filled with well preserved basal body below cusp and part of anterior process. At end of anterior process basal body is missing. Here cavity is narrow and a separate pit is visible below final denticle (Fig. 6C 1).

S 0 ?element (Fig. 6D):Alate. Only short parts of lateral processes preserved bearing discrete, slightly compressed denticles separated by U-shaped gaps. Cusp broken off but sub-circular in section at base. Basal cavity widest beneath cusp, with anteriorly and posteriorly flared lips better developed to posterior. Basal cavity completely filled with basal body.

Remarks.—The apparatus is poorly represented and the element available poorly preserved. However, the general morphology of specimens available (robustness, discrete laterally more or less compressed denticles, etc.) suggest that this apparatus, most probably, belongs to Ctenognathodus .