Anthracobune pinfoldi, Pilgrim, 1940

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 : 621

ANTHRACOBUNE PINFOLDI

In a vertical section of a P4 tooth, the enamel thickness is around 670 µm; the Schmelzmuster is twolayered. The inner zone is composed of radial enamel. The large outer zone, which represents 75% of the entire enamel thickness, presents a peculiar organization in which the prisms are parallel with each other but are not rectilinear, and they present undulations of great amplitudes. In some areas, undulations are so pronounced that decussations of bundles of prisms appear. On a horizontal section of the same specimen, the diameter of the prisms is around 5.5–7 µm in the inner zone; their cross sections are arc-shaped in outline. Near the OES, closed circles within hexagonal structures are visible ( Fig. 6C ); these structures are typical of poorly mineralized areas of the outer zone where prisms disappear in the IPM. The hexagons represent the area of one ameloblast, and the central circles may represent the trace of Tomes’ process. Reif (1974), Sahni & Koenigswald (1997), and Tabuce, Vianey-Liaud & Garcia (2004) observed the same structures in carnivores, extant dolphin, and Cretaceous mammal, respectively.

Figures

Figure 6. A, Numidotherium koholense, early Eocene, El Kohol, Algeria; vertical section of a lower molar showing zones of transition between areas of decussations; the prisms exhibit a keyhole cross section and the interprismatic matrix (IPM) is very reduced. B, Numidotherium savagei, late Eocene, Dor el Talha, Libya; vertical section of a lower molar with 3-D enamel near the enamel dentine junction (EDJ). C, Anthracobune pinfoldi, either late early or early middle Eocene, Kuldana Formation, Pakistan; horizontal section of a P4 near the outer enamel surface (OES), closed circles within hexagonal structures are typical of poorly mineralized areas of the outer zone; the hexagons represent the area of one ameloblast and the central circles may represent the trace of Tomes’ process. D, Seggeurius amourensis, early Eocene, El Kohol, Algeria; natural vertical section of an upper molar with a Schmelzmuster composed of radial enamel only. E, Crivadiatherium iliescui, late Eocene, Hateg Basin, Romania; vertical section of a molar showing modified radial enamel in the inner first-third of the enamel thickness; in this zone, the prisms are lanceolate in outline and the crystallites of the IPM are directed perpendicular to the prisms long axis.