Notidanodon brotzeni Siverson, 1995

Adolfssen, Jan S. & Ward, David J., 2015, Neoselachians from the Danian (early Paleocene) of Denmark, Acta Palaeontologica Polonica 60 (2), pp. 313-338 : 318-319

Notidanodon brotzeni Siverson, 1995

Fig. 2M.

1977 Notidanus? loozi Vincent : Herman 1977; 99, pl. 3: 8a.

1993 Notorhynchus seratissimus (Agassiz) ; Cvancara and Hoganson 1993: 3, fig. 2X, AA, non W, Z.

1995 Notidanodon brotzeni sp. nov.; Siverson 1995: 6, fig. 2I.

Material.—A single partly preserved specimen ( MGUH 1399) from the Br2 at Faxe and two fragmentary specimens in a private collection.

Description.—A labio-lingually compressed tooth with a main cusp and six mesial cusplets and six distal cusplets. The mesial cusplets increase in size towards the main cusp and are apico-distally directed with convex mesial cutting edges and concave distal cutting edges; the later feature dwindles toward the main cusp and the sixth mesial cusp has an almost straight distal cutting edge. The main cusp is inclined toward the commissure with a convex mesial cutting edge and a straight distal cutting edge. The two following distal cusplets after the main cusp have a similar morphology whereas the remaining cusplets appear to have a concave distal cutting edge mimicking the mesial cusplets. The crown-root boundary is apically convex. None of the teeth are preserved with roots.

Remarks.— Siverson (1995) differentiated N. brotzeni from N. loozi ( Vincent 1876) on the basis of the distal cutting edge of both the mesial cusps, the main cusp and the distal cusplets. They are straight or concave in the former and convex in the latter. None of the material from Kazakhstan ( Kordikova et al. 2001), New Zealand ( Mannering and Hiller 2008) and France ( Dutheil et al. 2006) that has been associated with N. brotzeni is sufficiently well preserved to be identified with absolute certainty as this species. An almost complete tooth illustrated by Floris (1979) from the Danish Paleocene appears unfortunately to have been lost. Teeth of N. brotzeni (or a very similar species) are fairly commonly collected from the Paleocene (presumed Selandian) of the Sidi Chenane mine, near Khouribga, Morocco ( DJW, personal observation). The reference by Siverson (1995) to a fragment figured by Arambourg (1952) from the Danian of Morocco is therefore supported, but it is too fragmentary to refer to a species. The Cretaceous species of Notidanodon ( N. lanceolatus , N. pectinatus , and N. dentatus ) differ from the species from the Paleogene ( N. brotzeni and N. loozi ) by the reduced size of the mesial cusplets and by the more distally directed distal cusps. The morphology of the Paleocene species is much closer to Hexanchus than to the Cretaceous species. Whether or not the species N. brotzeni and N. loozi should be included within Notidanodon is a matter of debate because the lower teeth differ considerably from those of the type species, N. pectinatus (Agassiz 1843) .

Stratigraphic and geographic range.— N. brotzeni is known from the middle Danian (early Paleocene) of Denmark (Faxe) and the contemporaneous Limhamn quarry in Southern Sweden ( Siverson 1995) as well as from the Paleocene of Morocco ( Arambourg 1952).