Premontreia Cappetta, 1992

Malyshkina, Tatiana, 2006, Late Eocene scyliorhinid sharks from the Trans-Urals, Russia, Acta Palaeontologica Polonica 51 (3), pp. 465-475 : 467-468

Genus Premontreia Cappetta, 1992

Type species: Premontreia degremonti Cappetta, 1992 .

Remarks.—The genus includes scyliorhinid sharks with fairly large teeth. The lingual face of the crown is convex and smooth, the labial face is less convex and slightly overhangs the root. There are vertical enamel folds at the base of the labial face. One or two pairs of cusplets may be present. The root extends behind the crown, its basal surface is flat with a wide nutritive groove. The central foramen is lingually placed.

In the palaeontological record several species of Premontreia are known. Two species were recorded from Morocco: Danian–early Ypresian P. subulidens ( Arambourg, 1952) and Thanetian P. peypouqueti Noubhani and Cappetta, 1997 . The type species, P. degremonti Cappetta, 1992 , was described from the late Ypresian of the Paris Basin. Kent (1999) recorded Premontreia degremonti Cappetta, 1992 in the early Ypresian of North America. P. dachiardi (Lawley, 1876) is known from the Oligocene up to the Pliocene of Europe ( Baut 1993; Genault 1993; Reinecke et al. 2001). P. gilberti (Casier, 1946) was described from the Eocene of France and Belgium; it is also known from the Thanetian of northern France (Moreau and Mathis 2000) and probably from the Ypresian of the USA ( Kent 1999).

This paper provides the first record of Premontreia from the West−Siberian Basin.

Noubhani and Cappetta (1997) divided Premontreia into two subgenera: Premontreia (Premontreia) with the type species Premontreia degremonti Cappetta, 1992 , and Premontreia (Oxyscyllium) with the type species Premontreia subulidens ( Arambourg, 1952) . The former, Premontreia (Premontreia) , has a convex crown labial face with short vertical, parallel, more or less flexuous folds, that never rise from the very base of the crown. The labial base of the crown does not form a border. There is one pair of cusplets, widely united with the main cusp, smooth, wide at the base. In some cases the cusplets are absent and the crown is indivisible in the labial view.

The latter, Premontreia (Oxyscyllium) , is distinguished by well developed and sharp cusplets, quite deviated and sometimes divergent. The labial face of the crown is smooth with the straight pleats, sometimes forming a more or less prominent bulge in the base of the crown.

The morphological characters of the new species described below correspond to the subgenus Premontreia .