From the estimation of the individual dental age to the descriptive model of the age structures of the fossil cohorts: the example of the Equidae and the time specific model in Pleistocene- Paleobiological contexts

In this study, the concepts of the two main models - attritional and catastrophic - often used in archaeozoology, are discussed from a methodological point of view. The characterization of the U and L age profiles, based on the frequency of individuals in each age group (f(x)), is presented within different palaeobiological contexts studied in various publications. Commonly applied methods are presented as well as predictive equations for Equidae for the estimation of age based on dental wear. As a step-by step example, the height of P4/ is used to estimate individual age, including its distribution in the various class-intervals according to the error ranges predicted by the model (E). Mammalian mortality is then regarded from the point of view of population dynamics (life tables) with the Time-specific model. This descriptive model of fossil cohorts and the main indices which can be calculated in each age group are presented in detail (l(x), q(x), e(x), k(x), m(x), R-0). The level of resolution of the model and its prospects for comparative analysis are discussed - especially between different taxonomical and chronological cohorts in particular palaeobiological contexts - and a brief presentation made of the Leslie matrix used in this kind of research.