Protospinax cf. annectans Woodward, 1919

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 : 591

Protospinax cf. annectans Woodward, 1919

Fig. 3F, G .

Material.—A complete tooth, BGRX 12505 ( Fig. 3F ), and an additional tooth crown, BGRX 12506 ( Fig. 3G ), Kłęby 1/37: 244.8–245.7 m. Callovian.

Description.—The complete tooth is small, less than 2.0 mm in mesio−distal width. The crown is mesio−distally expanded. The central cusp is low, rather broad and oval in cross section. It is slightly displaced distally and bent lingually. The labial face projects strongly over the crown/root junction forming a moderate visor. The basal edge of the labial face is rounded with a faint central concavity. The upper labial crown face is concave in lateral view. The lateral heels are unequally long with the distal one being shorter. There are two notches on either side of the main cusp separating it from the lateral heels. There are no distinct lateral cusplets but the cutting edge is strongly crenulated forming two pairs of very blunt and low cusplets. The cutting edge is continuous along the mesio−distal width of the crown.

The lingual face is steep and concave in lateral view. The lingual uvula is short, triangular in occlusal view and pointed. Both lingual and labial crown faces are completely smooth without any ornament.

The root is slightly lingually displaced. The vascularisation is of hemiaulacorhize type with two V−shaped lobes. The basal surfaces of the lobes are flat. The lingual protuberance is weak and damaged in its basal part where a medio−lingual foramen opens. A central foramen opens into the angle where both lobes are fused. The outline of the root is cordiform in basal view. There is one pair of margino−lingual foramina.

The second specimen is slightly larger and more mesio−distally elongated. The morphology of the tooth crown is almost identically to that of the other specimen. However, the upper labial crown face is only slightly concave in profile view. The overall morphology suggests a lateral position of this tooth.

Discussion.—The identification of teeth of Protospinax and Squalogaleus is often very difficult because of very similar morphologies. There exist some controversies about the validity of Squalogaleus , a taxon erected by Maisey (1976) for one articulated specimen attributed to P. annectans by Woodward (1919). This was strongly argued by Thies (1983) who regarded Squalogaleus a junior synonym of Protospinax . However, Cappetta (1987) accepted the validity of Squalogaleus presenting a range of dental characters for identifying teeth of Protospinax and Squalogaleus . Duffin (1993) also supported two different genera Protospinax and Squalogaleus respectively based on tooth morphologies. The tooth from Kłęby corresponds well to the characters indicated by both authors for Protospinax : moderate labial visor, triangular and elongated lingual uvula, upper labial crown face concave, and central foramen present. However, it differs slightly in the absence of a humped and convex upper lingual crown face. But this character seems to vary within a single species and might depend on the jaw position. The teeth figured by Thies (1983) as P. annectans also does not exhibit this hump−like structure but a concave lingual crown face in lateral view, which is very similar to the condition found in the Polish specimens.

Protospinax annectans is known from the Callovian of Germany ( Thies 1983) Oxfordian of Germany (Duffin 1993), Kimmeridgian of France ( Candoni 1995) and Tithonian of Germany ( Woodward 1919). The occurrence of a species at least closely related to P. annectans in the Callovian of Poland extends the geographic range of Protospinax further to the east. Protospinax is also known from the Toarcian ( Thies 1983) and the Bathonian (Charlie J. Underwood personal communication 2002).

Figures

Fig. 3. A. Paratype of Folipistrix digitulus gen. et sp. nov. SMNS 87862, Weilen unter den Rinnen, SW Germany, Dogger α, lower Aalenian; in labial view, × 52. B–C. Orectolobiformes, fam. gen. et sp. indet. Weilen unter den Rinnen, SW Germany, Dogger α, lower Aalenian. B. Specimen SMNS 87863; in labial view, × 85. C. Specimen SMNS 87864; in labial view, × 115. D. Holotype of Synechodus prorogatus sp. nov. BGRX 12503, Kłęby 1/37: 244.8–245.7 m, Callovian; in labial (D1), occlusal (D2), lateral (D3), and lingual (D4) views. All × 40. E. Isolated lateral cusplet of Synechodus prorogatus sp. nov., BGR X 12504, Kłęby 1/37: 244.8–245.7 m, Callovian; in labial (E1) and lingual (E2) views. Both × 30. F. Protospinax cf. annectans Woodward, 1919. Specimen BGRX 12505, Kłęby 1/37: 244.8–245.7 m, Callovian; in labial (F 1), lateral (F2), occlusal (F3), and lingual (F4) views. All × 65. G. Protospinax cf. annectans Woodward, 1919. Specimen BGRX 12506, Kłęby 1/37: 244.8–245.7 m, Callovian; in labial (G 1), lateral (G2), occlusal (G3), and lingual (G4) views. All × 32. H. Protospinax sp. 1. BGRX 12507, Kłęby: 244.8–245.7 m, Callovian; in labial (H 1), lateral (H2), occlusal (H3), and lingual (H4) views. All × 40. J. Protospinax sp. 2. BGRX 12508, Kłęby 1/37: 244.8–245.7 m, Callovian. Labial view. K. Squalogaleus sp. BGRX 12509, Kłęby 1/37: 244.8–245.7 m, Callovian; in labial (K1), lateral (K2), occlusal (K3), and lingual (K4) views. All × 50. L. Synechodus prorogatus sp. nov.? BGRX 12510, Kłęby 1/37: 253.6–~265 m, Callovian. Labial view, × 28. M. Scyliorhinidae indet. BGRX 12511, Kłęby 1/37: 253.6–~265, Callovian; in labial view, × 14. N. Neoselachii indet. BGR X 12512, Kłęby 1/37: 253.6–~265, Callovian; in labial view, × 22.