Description
Original diagnosis after (Arambourg, 1952) [90]: Notidanus a denture caracterisée par le grand développement, aux dents latérales de la machoire supérieure, de la première cuspide, comprimée et recourbée en forme d'S vers la commissure; denticules latéraux au nombre de 4 ou 5. Dents mandibulaires a 7 denticules au maximum, regulièrement décroissants. Bord antérieur de la première cuspide très finement denticulé à sa base.

Remarks
shark-references Species-ID=7511;

Remark of Welton (1979 [2517]): Prior to the recent collection of Heptranchias cf. "N." ancistrodon in the Lodo Formation of California, it was thought that this species was restricted to the Paleocene and Eocene of Morocco (Arambourg, 1952}. The only differences observed between the Lodo tooth (LACM 115912), and those figured by Arambourg (1952: Plate 1, Figures 65-67 and 78-79) are the presence of a small mesial serration and absence of a flared distal ledge at the apical end of the cusp in the Lodo specimen. It is not possible to evaluate characteristics of the mesial and distal cutting ridges from either Arambourg's description or illustrations. Arambourg referred teeth of the Lodo morphology (his Figures 65-67 and 78-79) to "dents des files plus reculees vers la commissure (Arambourg, 1952: 45)". It is my interpretation that Arambourg has incorrectly assigned the teeth to the upper dentition and that they actually represent a lower antero-lateral tooth group. All lower antero-lateral teeth in Hexanchus, Heptranchias, and Notorynchus possess a well developed mesial depression just below the crown foot but this character is absent in the upper symphyseal and antero-lateral tooth groups of all hexanchoids. This mesial depression houses the distal end of the root of the adjacent (mesial) row and functions to strengthen the dental series. All of the teeth figured by Arambourg (1952: Figures 65-67 and 80-82(*)) and all specimens of this same morphology in comparative collections at the LACM, show a well developed mesial depression. Moreover, in the case of all extant hexanchoids, the lower antero-lateral tooth positions average between 20 and 80 percent longer than the upper dentition. Following Arambourgs interpretation, his upper laterals are usually larger than the teeth he interprets to represent the lower antero-laterals of Notidanus (Heptranchias) ancistrodon. I consider Arambourgs Figures 65-67 and 78-79 to represent lower antero-laterals and his Figures 59-64 and 72-77 to represent upper antero-lateral and symphysial tooth positions. All of the above probably also include a mixture of Heptranchias "N." ancistrodon and Hexanchus microdon teeth. The teeth which Arambourg interprets to represent lower antero-laterals of H. "N." ancistrodon are all teeth of Hexanchus, probably H. microdon.
(*) should probably read: 78-79

valid after Ward (1979) p. 118 [2493]; Case (1996) p. 4 [397]

References