The enamel microstructure of the early Eocene pantodont Coryphodon and the nature of the zigzag enamel

An additional method for the investigation of the microstructure of enamel is described using the teeth of Coryphodon, Uintatherium, Entelodon, and Crocuta. Under low magnification natural surfaces or sections of teeth display details of the enamel microstructure when the light guide effect of prisms is used. Under the same low magnification even more details were obtained from sputter-coated surfaces of sections. The method is of particular significance for the investigation of large teeth with thick enamels when structures are somewhat irregular. The new method provides a better general survey, where scanning electron microscope images often show confusing details. The enamel of Coryphodon shows oblique lines of nested chevrons that are similar, to some degree, to the zigzag enamel in Crocuta, but a distinct asymmetry between ascending and descending lineaments was observed. This specific Coryphodon-enamel was also found in Uintatherium and Entelodon. This enamel type, which evolved several times in parallel, cannot be attributed to a specific diet, but must be regarded as one of the several ways to strengthen the enamel against breakage.