Ptychotrygon undetermined

Kriwet, Jürgen, Nunn, Elizabeth V. & Klug, Stefanie, 2009, Neoselachians (Chondrichthyes, Elasmobranchii) from the Lower and lower Upper Cretaceous of north-eastern Spain, Zoological Journal of the Linnean Society 155 (2), pp. 316-347 : 335

PTYCHOTRYGON SP. ( FIG. 10I–L )

Material: Two teeth lacking the roots, MPZ 2005-27 and MPZ 2005-28.

Occurrence: Sample 4 from floodplain environments with channel deposits (facies 2) of the lower Mosqueruela Formation (lower Cenomanian), Aliaga subbasin.

Description: The teeth are very broad, with a triangular, cuspidate crown. The central cusp is lingually placed, with a very well-marked transverse occlusal ridge running through the apex. There is an equally well-marked transverse labial ridge, before two fainter longitudinal labial ridges that stop just above the broad and rounded apron. The lingual face is very steep and has a poorly developed uvula. On the lingual face are three strong triangular folds, each pointing towards the apex. The central fold is the largest, and is located above the uvula. This is surrounded on each side by a smaller, fainter triangular fold. The root is low.

Remarks: This species resembles teeth of P. boothi Case, 1987 from the Campanian of Wyoming ( USA) in the labial and lingual crown ornamentation but is different from the American species in the discontinuous lingual transversal ridge. In addition, the low crown and its ornamentation, consisting of a single labial crest accompanying the transversal cutting edge, a triangular ridge roofing the lingual interlocking depression, which is very weakly developed, and additional short lingual ridges below the lateral heels distinguish this species from all other known Ptychotrygon species. However, the teeth are too fragmentary to allow a new species to be erected.

Figures

Figure 10. A–H, Ptychotrygon geyeri (Kriwet, 1999a). A–D, anterior tooth. A, labial view. B, lateral view. C, lingual view. D, occlusal view. E–H, lateral (juvenile?) tooth. E, labial view. F, lateral view. G, lingual view. H, occlusal view. I–L, Ptychotrygon sp., lateral tooth. I, labial view. J, lateral view. K, lingual view. L, occlusal view. M–X, Ptychotrygon pustulata sp. nov. M–P, antero-lateral tooth. M, labial view. N, lateral view. O, lingual view. P, occlusal view. Q–T, anterior tooth. Q, labial view. R, lateral view. S, lingual view. T, occlusal view. U–X, lateral tooth. U, labial view. V, lateral view. W, lingual view. X, occlusal view. All scale bars equal 0.5 mm.