Article: The microstructure of tooth enamel in multituberculate mammals

The enamel microstructure of single teeth and teeth in situ in whole jaws of late Jurassic, late Cretaceous, and Palaeocene multituberculates belonging to the Plagiaulacoidea, Taeniolabidoidea, Ptilo-dontoidea, and Meniscoessus (Cimolomyidae, suborder indet.) is examined by incident light microscopy, scanning electron microscopy (SEM), and polarized light microscopy. For comparison one docodont tooth and some single late Cretaceous and Recent eutherian teeth are included. The enamel of the Plagiaulacoidea like that of the docodont tooth is not prismatic, but consists of radially arranged, closely packed 5 um thick columns of crystals, which diverge from the central axis of each column towards the outer enamel surface. The Asian as well as the North American Taeniolabidoidea have gigantoprismatic enamel, the numerical density of prisms per unit area being four to five times lower than in the Ptilodontoidea and Eutheria. In most taeniolabidoid jaws the prism density is somewhat higher in the molars than in the incisors. The oldest gigantoprismatic enamel was found in some undescribed multituberculate teeth from the early Cretaceous of Asia. As Meniscoessus (suborder indet.) has gigantoprismatic enamel, it is suggested that this feature may be useful in establishing the taxonomic position of some multituberculate groups.