Gladioserratus sp.

Adolfssen, Jan S. & Ward, David J., 2015, Neoselachians from the Danian (early Paleocene) of Denmark, Acta Palaeontologica Polonica 60 (2), pp. 313-338 : 318

Gladioserratus sp.

Fig. 2J.

Material.—Two almost complete specimens embedded in matrix (MGUH 29827, GMV2012-59) and four incomplete in a private collection, all collected from the Br 2 in Faxe.

Description.—Labio-lingually compressed teeth with a triangular main cusp slanted towards the commissure and three cusplets distally diminishing in size. Mesial to the main cusp are five or six small mesial cusplets, which increase in size towards the main cusp. The distal part is missing in one tooth, but it does not appear to have had more than three cusplets. The root is compressed, with a convex mesial face (partly missing in the figured specimen). The basal edge of the root is also rounded, leaving a slightly triangular outline of the root in lingual view.

Remarks.—The teeth found in the quarry of Faxe are very similar to the teeth described by Siverson (1995: 5) and are presumable conspecific. Underwood et al. (2011) erected the new genus Gladioserratus to contain the Cretaceous species N. aptiensis ( Pictet, 1865), distinguishing it from Notorhynchus by its lower and mesially “rounded” root and by having more massive cusps and an evenly mesial serration. The material from SNM is embedded in matrix and the thickness is difficult to estimate, but is presumably less than 3 mm, and two incomplete specimens in a private collection are both less than 2 mm thick. As noted by Underwood et al. (2011) the Scandinavian material lies somewhere between Gladioserratus and Notorynchus as the root is much like the former but the crown is more like the latter with its cockscomb-like serration. As material is limited, we refrain from erecting a new species and agree with Underwood et al. (2011) that more material is needed before such a decision can be made. Teeth of the early Eocene species Notorynchus seratissimus (Agassiz, 1843) more closely approach those of Gladioserratus than Recent Notorynchus and should probably be included in Gladioserratus . In particular they possess a similar mesially and distally rounded root profile as seen in Gladioserratus and have fewer distal cusplets than Recent teeth of Notorynchus . The mesial cusplets (cockscomb), however, resemble more closely those of Notorynchus in being distinct and increasing in size as they approach the main cusp. In this, they are similar to the Scandinavian material. This feature is much less developed in juvenile teeth, where the mesial cusplets are less developed or virtually absent as in G. aptiensis .