HARVESTER ANTS

This paper presents the results of a study of decomposition and disarticulation of kangaroo carcasses in caves at Naracoorte, South Australia. Carcasses were placed in two caves and observed over a period of nearly three years. Decomposition progressed rapidly within the caves with almost immediate infestation by blowflies and fungi. Invertebrate activity had ceased by 28 months; however, fungal colonisation continued for the course of the study period. Decomposition, skeletonisation and disarticulation were complete by 600 days. The results suggest that temperature and humidity play an important role in decomposition as this directly affects the activity of invertebrate and fungal decomposers. The position of the carcass within the cave influences the degree of dispersal of remains in pitfall caves. Disarticulation sequences for the experimental carcasses compare with those for kangaroo skeletons on the land surface in semi-arid South Australia, suggesting that regardless of environment, anatomy is a key factor in determining disarticulation sequence. The results of this study have applications for the assessment of stratigraphic integrity and reworking of fossil deposits in caves at Naracoorte and elsewhere.

On the High Plains of North America the harvester ants Pogonomyrmex occidentalis and P. owyheei build large gravel covered nest mounds in which artifacts and small fossils are frequently deposited. The effect this mound building behavior has on the archaeological record has received little attention and has generally been viewed as restricted to subsurface tunneling disturbances. Initial experiments highlight the surface foraging behavior of harvester ants actively transporting artifacts during mound construction and maintenance. Non-food related foraging behavior was investigated by placing glass beads around ant mounds in various patterns to evaluate foraging distance, direction, density and distribution effects. Ants were observed to forage a maximum of 48 m from the nest but the majority of foraged materials were returned from within 20 m, regardless of density, direction, or distribution differences. Of 812 individual mounds recorded during an extensive landscape survey, 134 contained anthropogenic debris. Additionally, mounds tend to form near disturbed and eroding soils which enhance the opportunity for ants to acquire actively exposed artifacts during foraging for mound construction material. These characteristics of harvester ant foraging effectively create highly visible loci of small artifact concentrations that are otherwise poorly represented by traditional pedestrian surveys. Understanding the taphonomic signature of harvester ant artifact transport should aid in refining interpretations of artifact patterning observed in archaeological contexts.

The Middle Pleistocene is a period with a great variability of carnivores. Different species of big cats, hyaenids, bears and canids are common in faunal lists of anthropogenic assemblages. This phenomenon raised a discussion about the relationships between carnivores and hominids. This paper aims to provide data to understand the presence of carnivore remains or the elements generated by them in Middle Pleistocene anthropogenic assemblages. We analyze two Spanish sites for this specific work: TD10-sup of Gran Dolina (Sierra de Atapuerca, Burgos) and Level XII of the Bolomor Cave (Valencia, Spain). The origin of both accumulations is due to the predatory activities of humans and carnivores´ incidence is very low. The main objective of this study is to determine the role of predators in these accumulations and to evaluate their relationship with human communities. The anatomical representation of carcases, the age of death of animals, the identification of anthropogenic marks and tooth marks, and the morphology of the latter suggest the existence of marauding small scavengers. These animals visited the cavities once abandoned by hominids. From this perspective, we think that there are not direct relationships in the form of interaction between both biological entities.