Aging through growth marks in teeth of Spanish red deer

Abstract

We carried out a study on age determination for Spanish red deer (Cervus elaphus hispanicus) from growth marks in dental cementum. We investigated the age at which the first growth layer and first rest line appear in cementum of incisors (I1), molars (M1), and canines (C), and explained how to interpret these marks to determine age. We evaluated accuracy and precision of aging with rest lines of different tooth types. Age was estimated using a standardized counting method and a linear regression analysis, both based on rest-line number in permanent teeth of red deer aged between 4 and 44 months. The first growth layer occurred after dental eruption in all teeth studied. The first rest line appeared at 6 months in molars (M1) and at 15 months in incisors (I1). The second rest line appeared at 18 months in molars and incisors. Each consecutive rest line represented one year more in animal age. Subsequent analysis showed that canines do not give an accurate estimation of the real age. Molars and incisors did not yield the same values for age estimation. Molars gave the best results, aging 75% of animals correctly, while only 49% were aged correctly using incisors. Nevertheless, within a one-year confidence interval, 99% of the animals were aged correctly using molars, versus 86% using incisors. We suggest using the first lower molar for deer aging in Sierra Morena. Use of regression should be preferred to the standardized counting method for age determination when using incisors.