Cochliodontiformes Obruchev, 1953

Ginter, Michał & Sun, Yuanlin, 2007, Chondrichthyan remains from the Lower Carboniferous of Muhua, southern China, Acta Palaeontologica Polonica 52 (4), pp. 705-727 : 718

Order Cochliodontiformes Obruchev, 1953 Family Cochliodontidae Owen, 1867 Genus Deltodus Morris and Roberts, 1862

(ex Agassiz ms. 1859)

Deltodus sp.

Fig. 7F .

Material.—Two incomplete tooth−plates.

Description.—The plates have a wavy shape with the main, convex part covered with a few vague ridges made of tubular dentine, and a triangular lateral wing. The specimens resemble to some extent the tooth−plates of Deltodus sublaevis Agassiz, 1838 ( Fig. 10E ), but their state of preservation precludes the precise identification.

Figures

Fig. 7. Holocephalian dental elements from sample MH−1, middle Tournaisian of Muhua, China. A. Diclitodus denshumani (Newberry and Worthen, 1866), PKUM02−0153, in lingual (A1), lingual/aboral (A2), labial (A3), and lateral (A4) views. B–E. Helodus coniculus Newberry and Worthen, 1866. B. PKUM02−0154 in oral (B1) lingual (B2), and lateral (B3) views. C. PKUM02−0155 in lingual (C1), oral (C2), and two lateral (C3, C4) views. D. PKUM02−0156 in lateral (D1), labial (D2), and oral (D3) views. E. PKUM02−0157 in aboral/lateral (E1) and aboral (E2) views. F. Deltodus cf. sublaevis (Agassiz, 1838), tooth plate (PKUM02−0158) in labial view.

Fig. 10. Reference specimens from Laurussia. A. Diclitodus scitulus Davis, 1883, holotype (BMNH P.49629), from the Carboniferous Limestone, Richmond, Yorkshire, England, in labial view. B. “?Psephodus laevissimus”, specimen BMNH P.9914, from the Lower Limestone shales bone bed, Avon Gorge near Bristol, in oral view. C. Chomatodus davisi (Woodward, 1889), a specimen of the type series (BMNH P.2656), from the Viséan Mountain Limestone of Armagh, Northern Ireland, in lingual view. D. Tamiobatis wachsmuthi (St. John and Worthen, 1875), a specimen of the type series (MCZ 6371), from the Kinderhookian of Burlington, Iowa, in labial view. E. Deltodus sublaevis (Agassiz, 1838), specimen BGS 5964, from the Viséan Mountain Limestone of Armagh, Northern Ireland, in oral view (left side broken). F.?Goodrichthys eskdalensis (Moy−Thomas, 1936), a tooth from the specimen NMS 2000.14.2, from the lower Viséan of Glencartholm, Dumfriesshire, Scotland, in labial view. G. Chomatodus linearis (Agassiz, 1838), specimen BMNH P.2653, from the Lower Carboniferous Yoredale Beds, Richmond, Yorkshire, England, in oral view. H. Sibyrhynchus denisoni Zangerl and Case, 1973 (FMNH PF6408), palatal tooth plates.