Bone weathering in guanaco and Greater Rhea

Abstract

Bone weathering has been widely used in taphonomic and zooarchaeological analyses given its importance in assessing the integrity and the depositional context of archaeological materials. In this paper we present the results of a long-term experimental study undertaken on bones from guanacos of three different age classes, as well as an adult Greater Rhea, at eight years of exposure. The aim of this research was to evaluate if weathering differentially affected bones from both species, across the different age classes, and on diverse skeletal parts from the same carcass. Our results indicated that, in general terms, rhea bones weathered faster than the skeletal parts of guanaco belonging to the same age group. Likewise, guanaco bones belonging to immature individuals showed higher weathering rates than those from the adult, and after two years of exposure all the skeletal parts of the three guanacos presented some degree of weathering. Furthermore, guanaco skulls and teeth were the most affected elements across all three age classes. Finally, under increased exposure time, the axial skeleton showed slightly higher weathering stages than the appendicular skeleton. These preliminary results contribute to improving our understanding of the complexity inherent to the weathering process, while also building a more solid taphonomic database against which to model our archaeological expectations.