Northern Prairie Wildlife Research Center
Thirty-eight swift fox skulls were used in this study. Of these, nine were of known age. The lower left canine tooth was used whenever possible. The teeth were preserved in neutral 10% formalin, decalcified by first soaking in 5% nitric acid and then buffered in formic acid. The teeth were frozen at -16C and cut into 10-micron longitudinal sections. Staining was done using toluidine blue.
All readings were made with a wet mounted cover slip. To test accuracies, 3 readers were given the same slide. In 87% of the time all 3 readers were in agreement. With known aged teeth, accuracy was achieved 89% of the time.