Occurrence of a postpermanent mandibular fourth premolar in a moose bull (Alces alces L.).

By a number of diagnostic criteria a supplemental premolar in the right hemimandible of a 6-yr-old moose bull from Bielorussia was identified as a postpermanent fourth premolar. Its development, which must have started at least 3 yr after the permanent fourth premolar had reached its functional position, resulted in rotation of the P4 by 80 degrees, as well as extensive resorption on both root and crown.