Generalized individual dental age stages for fossil and extant placental mammals

The traditional age stages for eutherian mammals (infant, juvenile, adult, senile) can be difficult to apply in the fossil record. Based on the tooth eruption and wear of the cheek teeth we propose six “individual dental age stages” (IDAS) that can be applied to almost all fossil and extant mammalian dentitions. The six stages of IDAS cover the entire life span. Traditional terms can be correlated to the IDAS stages and thus redefined based on the dentition: IDAS 0—prenatal, IDAS 1—infant, IDAS 2—juvenile, IDAS 3—adult, IDAS 4—late adult, and IDAS 5—senile. Furthermore IDAS enables comparison between individuals, characterizing the mortality in monospecific populations, and even of entire communities composed of various species. The data obtained can be used for paleoecological interpretations. The varying duration of different stages in the IDAS pattern during the life history forms an additional way to characterize mammalian groups by development and wear of their dentition.