Mean body size estimation in large mammals and the computation of biomass in past ecosystems: An application to the Pleistocene sites of Orce and Sierra de Atapuerca (Spain)

Estimates of adult body mass are usually considered as equivalent of mean population body size in most studies of ancient mammals. However, given that any population is composed in part of subadult individuals, this approach overestimates the mean population body mass and biomass. For this reason, more realistic estimates of mean population body mass should be used. In this paper, we: 1) test five different proxies of population mean mass; and 2) estimate the total prey biomass in the paleoecosystems from the Orce and Atapuerca sites as an approach for estimating their carrying capacity. Our results for past ecosystems support the use of survival profiles derived from the Weibull model (SPW), as they show values in better agreement with those of extant populations. They also estimate higher carrying capacities for the faunal assemblages of Orce than for those of Atapuerca. We suggest that the environmental conditions of Orce could have played an important role in the first peopling of Europe.