Estimation of the age of the Koala, Phascolarctos cinereus (Marsupialia: Phascolarctidae), from tooth wear and growth.

Abstract

Wear of the premolar and molar teeth of the Koala, Phascolarctos cinereus, was studied at two localities, in central and southern Queensland respectively. Tooth wear was classified into 10 tooth wear classes (TWC). Mean ages were determined for TWCs 1- 6, ranging from 1.2 to 7.3 years. An age estimate is also given for TWC 7 (9 years), but is based on data from only one known age animal. Rate of tooth wear varied greatly between animals from the same area, but there was no difference in rate of wear between the two localities, at which diets differed (Eucalyptus tereticornis / E. microtheca versus E. populnea). TWC is useful for dividing samples of animals from P. cinereus populations into separate age classes and for giving an approximation to the age of particular animals. The correlation between age and head length of P. cinereus of known year class was examined. Head length differs between P. cinereus from year classes 0, I and 2, and may be used to place animals in this age range into a year class.