Abstract
Two rare anomalous dental morphologies were observed in living Japanese raccoon dogs (Nyctereutes procyonoides viverrinus). One specimen exhibits an extra third root on P3, and the other exhibits a mesiodistally shortened, buccally swelled, and occlusally triangular P4. Analogous morphologies also occur in two Eocene mammalian species, Brachyhyops viensis and Brachyhyops trofimovi (Artiodactyla; Entelodontidae). Brachyhyops viensis has a third root on P3, and B. trofimovi has a mesiodistally shortened, buccally swelled, and occlusally triangular p4. These morphologies of the Eocene species have been considered as diagnostic at the species level. However, the presence of analogous dental morphologies in the anomalous teeth of the raccoon dog imply a possibility that a part of the species diagnoses of B. viensis and B. trofimovi may be not diagnostic characters but anomalous morphologies.
