Hahnodon Sigogneau−Russell, 1991a

Hahn, Gerhard & Hahn, Renate, 2003, New multituberculate teeth from the Early Cretaceous of Morocco, Acta Palaeontologica Polonica 48 (3), pp. 349-356 : 351

Genus Hahnodon Sigogneau−Russell, 1991a

Type species (monotypy): Hahnodon taqueti Sigogneau−Russell, 1991a .

Distribution.—Early Cretaceous (?Berriasian) of Morocco (Anoual Syncline, eastern High Atlas).

Revised diagnosis.—The type genus of the Hahnodontidae has the following characteristics: Posterior lingual cusp (l3) of m2large. Posterior buccal cusps completely reduced. Lin − gual wall of crown deeply indented between anterior and posterior cusp.

Description.—See Sigogneau−Russell 1991a: 120–122.

Discussion.—The holotype of H. taqueti ( Sigogneau−Russell 1991a: figs. 1a, 2a, b) is a left m2, as correctly stated by the author. The tooth resembles, besides the presence of the anterobuccal cusp, the m2of Kuehneodon (compare Fig. 1C ). Both teeth show a relatively large anterior and a smaller posterior lingual cusp, separated one from the other by the indentation of the lingual wall.

In Kuehneodon ( Fig. 1C ), the anterolingual cusp is composed of originally two, now confluent cusps, the smaller l1 and the larger l2. Consequently, the posterolingual cusp is l3.

In Hahnodon ( Figs. 1A , 2A ) the anterolingual cusp is severely eroded. But the comparison with Denisodon ( Figs. 1B , 3A–E ) shows that this cusp is a morphological unit, not composed of two cusps. Nevertheless, the posterolingual cusp, in Hahnodon , is cusp l3, as is indicated by its position on the crown.

Figures

Fig. 1. Comparision of left lower m2in Paulchoffatioidea superfam. nov. A. Hahnodon taqueti Sigogneau−Russell, 1991a; redrawn from Sigogneau− Russell, 1991a: fig. 2c. B. Denisodon moroccensis gen. et sp. nov. C. Kuehneodon sp.; redrawn from Hahn and Hahn 1998: fig. 39b. D. Pinheirodon sp.; redrawn from Hahn and Hahn 1999b: fig. 29c.

Fig. 2. Hahnodon taqueti Sigogneau−Russell, 1991a, holotype, left m2, MNHN SA 33, in occlusal (A) and lingual (B) views. Drawn after Sigogneau−Russell 1991a: fig. 2c, a, respectively. Scale bar 1 mm.

Fig. 3. Denisodon moroccensis gen. et sp. nov., right m2, holotype, MNHN SA 97, in occlusal (A), buccal (B), lingual (C), anterior (D), and posterior (E) views; in A anterior is up. Scale bar 1 mm.