Roulletia, Vullo & Cappetta & Néraudeau, 2007

Vullo, Romain, Cappetta, Henri & Néraudeau, Didier, 2007, New sharks and rays from the Cenomanian and Turonian of Charentes, France, Acta Palaeontologica Polonica 52 (1), pp. 99-116 : 106

Genus Roulletia nov.

Type species: Roulletia bureaui sp. nov.

Derivation of the name: From the name of the type locality.

Diagnosis and comparisons.—Small Odontaspididae , characterized by rather bulbous teeth with a cusp showing a strong labial bulge. The lingual and labial faces are completely smooth. There is only one pair of divergent, very small sized, sometimes incipient, lateral cusplets. An additional minute distal cusplet can develop. The mesial edge is slightly concave in antero−lateral teeth. The teeth of this genus have a more bulbous labial face and one pair of proportionally smaller cusplets than in other odontaspidids. They are also distinguished from teeth of “ Carcharias ” amonensis, the morphologically closest taxon, by a thicker crown and root (labio−lingually compressed in “ C. ” amonensis), and in having fewer and smaller lateral cusplets (generally two pairs in “ C. ” amonensis). The teeth of Roulletia gen. nov. mainly differ from those of Cenocarcharias Cappetta and Case, 1999 by a smooth crown. From the teeth of the cretoxyrhinid? Dallasiella Cappetta and Case, 1999 they are distinguished by their weaker lateral cusplets and their clear, well developed nutrient groove on the lingual protuberance of the root.

Remarks.—Relatively few odontaspidid genera have been reported in Cretaceous deposits: Carcharias Rafinesque, 1810 , Cenocarcharias Cappetta and Case, 1999 , Hispidaspis Sokolov, 1978 , Johnlongia Siverson, 1996 , and Odontaspis Agassiz, 1838 . The genera Cenocarcharias and Hispidaspis have teeth whose base of the cusp is strongly folded labially, and even lingually for the first one. The teeth of Roulletia gen. nov. have a completely smooth enamel and so can be easily separated from Cenocarcharias and Hispidaspis . Roulletia gen. nov. has teeth with cutting edges which are in continuity between the cusp and the cusplets, that separates it from the genus Odontaspis in which the cutting edges do not reach the base of the cusp nor of the cusplets, mainly in the anterior files. Moreover, the teeth of Odontaspis have sharp and high cusplets, often duplicated, that is not the case of Roulletia gen. nov. in which they are simple and low. The teeth of the genus Johnlongia have a very particular morphology, mainly in the anterior files whose root shows a very salient lingual protuberance, much more developed than in Roulletia gen. nov. In the lateral files, the cusplets are sometimes duplicated mesially and the base of the labial face is often folded. The teeth of Roulletia gen. nov. are characterized by a not very high cusp compared to the root. In lingual view, the cusp is indeed practically as high as the root. By this feature, Roulletia gen. nov. is distinguished easily from Carcharias whose teeth, mainly in the anterior files, have a cusp clearly higher than the root. Moreover, as already noted, the teeth of Roulletia gen. nov. have a completely smooth enamel, while in Carcharias the lingual face of the teeth bears more or less numerous and marked folds.