Squaliodalatias sp.

Underwood, Charlie J. & Schlögl, Jan, 2013, Deep-water chondrichthyans from the Early Miocene of the Vienna Basin (Central Paratethys, Slovakia), Acta Palaeontologica Polonica 58 (3), pp. 487-509 : 496

Squaliodalatias sp.

Fig. 6H.

Material.—One rather damaged lower tooth, SNM Z 27462.

Description.—The only recorded tooth is 1.6 mm high and strongly labio−lingually compressed. The tooth is about 1.5 times as high as wide and, damage to the distal part notwithstanding, rather rectangular in profile. There is a single cusp that is very strongly inclined distally with the mesial edge of the cusp being close to 90° to the mesial edge of the tooth. The cusp reaches almost to the distal edge of the tooth, and has weakly convex mesial and distal cutting edges that lack serrations. Distally, the cusp overhangs a semicircular distal heel. There is a well developed cutting edge on the cusp and a distal heel. The tooth below the cusp has a weakly convex distal edge (as far as can be seen) and very straight mesial edge. The labial tooth face is largely covered by enameloid, which reaches at least three quarters of the way to the base of the tooth. There is a rather subtle concavity on the mesial side of the tooth, with the upper part of the concavity having an enameloid cover. There is a foramen at the base of the enameloid within this concavity. A very large and prominent foramen is present on the lower part of the tooth labial face, forming the top of a wide and deep vertical groove. Smaller foramina are present both mesial and distal to the main foramen. On the lingual face of the tooth, a broad ridge is present from the base of the crown to the base of the root, comprising the central third of the tooth width at the top and widening downwards. Somewhat symmetrical concavities are present on the mesial and distal sides of this ridge. The basal edge of the enameloid is at the top of the mesial and distal concavities and extends about a third of the way down the central ridge. A major foramina is present close to the centre of the root lingual face.

Remarks.—The single tooth of this species is not dissimilar to the anterior teeth of Squaliolus schaubi , but can be separated from them by the greater overall height of the tooth, lower cusp, larger main labial foramen and weaker and partly enameloid−covered mesial concavity. There are strong resemblances with the anterior teeth of Squaliodalatias weltoni Adnet, Cappetta, and Reynders, 2006b from the Eocene of France, which shares the same overall tooth proportions and the very large labial foramen, and as such this tooth is assigned to the same genus. Our specimen differs from Squaliodalatias weltoni in having a lower cusp without a concave mesial edge and a less well defined mesial concavity. This genus possibly occurs in the Oligocene of California ( Welton 1979) and Langhian of France ( Cappetta 1970: 76, fig. 9; Ledoux 1972: 161, fig. 12; Adnet et al. 2006b: 64).