Pseudospinax, Muller and Diedrich, 1991

Kriwet, Jürgen, 2003, Neoselachian remains (Chondrichthyes, Elasmobranchii) from the Middle Jurassic of SW Germany and NW Poland, Acta Palaeontologica Polonica 48 (4), pp. 583-594 : 585

Pseudospinax ? sp.

Fig. 2B .

Material.—Two isolated teeth lacking roots (BGRX 12500, BGR X 12501), Kłęby 1/37: 244.8–245.7 m. Callovian.

Description.—The crown of both teeth is very flat labio−lingually and completely smooth on both lingual and labial crown faces. The labial crown face is plane and mesio−distally expanded with a cordiform outline. The basal edge is regularly convex. In lateral view, the labial face is also more or less flat without any concavity between central cusp and crown shoulder. The central cusp is slender, pointed and bent lingually. The transverse cutting edge is distinct and is continuous between the central cusp and the lateral heels. The cutting edge of the distal heel is angled forming an incipient, rudimentary cusplet whereas the mesial one is convex without any cusplet. The lingual face is much reduced and more convex. The lingual protuberance is prominent and supports a tapering and rather short lingual uvula. The root is completely missing.

Remarks.—The genus Pseudospinax was erected for isolated teeth from the Cenomanian of NW Germany by Müller and Diedrich (1991). Underwood and Mitchell (1999) attributed material from the Albian of England to this genus and presented an amended diagnosis. The main distinguishing feature from similar teeth of Protospinax is mainly the absence of a basal concave labial crown edge, a lower root and a less well defined uvula. Subsequently, Underwood (2002) attributed an isolated tooth crown from the Kimmeridgian of England to this genus expanding its range into the Jurassic. The specimens from Kłęby exhibit the typical crown morphology of teeth of Pseudospinax . However, the character “round and not concave labial crown edge” seems to vary within Protospinax from being absent to present. Consequently, the attribution of the specimen to Pseudospinax is provisional until additional material is available to study its morphology in more detail.

Figures

Fig 2. A. Hybodontiformes indet. BGRX 12499; in lateral (A 1, A2) and occlusal (A3) views. All × 40. B. Pseudospinax? sp. BGRX 12500, Kłęby 1/37: 244.8–245.7 m, Callovian; in occlusal (B1), lateral (B2), and lingual (B3) views. All × 80. C. Palaeobrachaelurus sp. BGRX 12502, Kłęby 1/37: 244.8–245.7 m, Callovian in labial view (C1), × 55, occlusal view (C2), × 55, lateral view C3, × 55, lingual view (C4), × 55, and basal view (C5), × 40. D. Holotype of Folipistrix digitulus gen. et sp. nov. SMNS 87861, Weilen unter den Rinnen, SW Germany, Dogger α, lower Aalenian; in labial view (D1), × 50, lateral view (D2), × 50. lingual view (D3), × 45, latero−lingual view (D4), × 45, and basal view (D5), × 45.