A shrew incisor
This tiny black tooth (a right lower incisor) measuring about 1mm, was just identified in the Fishbowl Lab under the microscope. It is pictured here with the complete right lower jaw of a modern specimen of long-tailed shrew (genus Sorex) for comparison. The red on the tips of the teeth is accumulated iron which may function to strengthen the enamel. The diet of a shrew consists mainly of arthropods and their closest relative is the mole. Either due to their diminutive size or their rarity in the L.A. basin, there are only 20 specimens known from the tar pits. It is not possible to tell which species this is based on this tooth.