The use of age—frequency distributions of micromammals in the determination of attritional and catastrophic mortality of fossil assemblages

Abstract

Many authors have used age—frequency profiles of fossil populations of large mammals to determine whether an assemblage is the result of catastrophic or attritional mortality. The smallest mammals previously used had calculated life spans of seven years or more. The use of small mammals (rabbit-sized or smaller) with much shorter life spans has never previously been done. Based on data from known fossil catastrophic assemblages and modern attritional assemblages of micromammals, it is evident that age—frequency profiles from these mammals are nearly identical to those of larger mammals and can be used in the same manner. Several fossil examples of both catastrophic and attritional mortality are cited. One example of a micromammal fauna can best be interpreted as a combination of catastrophic and attritional mortality. It is suggested that such a profile would not be recognizable in larger animals from the same horizon.