Khamsaconus bulbosus

Tabuce, Rodolphe, Delmer, Cyrille & Gheerbrant, Emmanuel, 2007, Evolution of the tooth enamel microstructure in the earliest proboscideans (Mammalia), Zoological Journal of the Linnean Society 149 (4), pp. 611-628 : 613

KHAMSACONUS BULBOSUS

No enamel section was carried out because Khamsaconus is documented only by its holotype. The specimen is a molariform DP4 composed of two fragments that were joined during the initial preparation of the fossil. After we cautiously removed the two fragments, we observed the microstructure on a somewhat vertical natural fracture of the buccal wall. As in most mammalian deciduous teeth, the enamel thickness is reduced (around 85 µm). The Schmelzmuster is simple, and exclusively constituted of radial enamel ( Fig. 1A ). The prisms have a slightly curved course from the enamel dentine junction (EDJ) to the OES. The diameter of the prisms is estimated to be around 2.5–3 µm; the prism cross sections cannot be characterized. The interprismatic matrix (IPM) is well developed. The radial enamel observed in the DP4 of Khamsaconus is considered to be representative of the genus because the specimen is a molariform tooth. In the same way, the posterior deciduous premolars of N. koholense show the same structures as those observed in molars (see below).

Figures

Figure 1. A, Khamsaconus bulbosus, earliest Eocene, N’Tagourt 2, Ouarzazate Basin, Morocco; natural vertical fracture of the DP4 (holotype and unique specimen) with radial enamel. B, Phosphatherium escuilliei, earliest Eocene, Ouled Abdoun Basin, Morocco; vertical section near the outer enamel surface (OES), with irregular prism cross sections that vary from open to closed. C, same sample as in (B) showing Hunter-Schreger bands (HSB) and the typical keyhole cross sections of the prisms in the ‘ginkgo-tree-leaf ’ pattern. D, same sample as in (B) and (C) near the enamel dentine junction (EDJ), the interprismatic matrix (IPM) crystallites show the same orientation as the long axis of prisms.