The enamel microstructure ofAnchitheriomys (Rodentia, Mammalia) in comparison with that of other beavers and of porcupines

In the enamel microstructure of the incisors, porcupines (Hystricidae) are characterized by multiserial Hunter-Schreger bands (HSB) while beavers (Castoridae) basically have uniserial HSB. In addition, two groups can be differentiated among beavers based on enamel microstructure.Palaeocastor, Steneofiber andCastor show rather typical uniserial HSB. OnlyCastor shows a slight tendency of fusion of the bands. In contrast,Trogontherium andCastoroides are characterized by the regular occurrence of fused bands.Anchitheriomys, having uniserial HSB and a high frequency of fused bands fits well with theTrogontherium group, proving the castorid nature ofAnchitheriomys. Furthermore, the enamel differentiation observed among the Castoridae thus provides an important character for further systematic subdivision of the beavers. In the enamel of the cheek teeth, porcupines can be told apart from beavers as well.Anchitheriomys shows a two-layered schmelzmuster with inner radial enamel like other beavers. Porcupines have thick HSB throughout the enamel layer. This character in the cheek teeth facilitates the separation of isolated beaver teeth from porcupine teeth.