Spotted hyena (Crocuta crocuta) den use and taphonomy in the Masai Mara National Reserve,Kenya

Hyena taphonomy is of great importance to studies of hominid evolution, since these carnivore taxa have the highest potential both to produce large osseous assemblages and to modify existing hominid-accumulated assemblages throughout the Old World. The three extant hyena species (brown: Parahyaena brunnea; striped: Hyaena hyaena; and spotted: Crocuta crocuta) are all significant bone collectors and modifiers. Spotted hyenas generally have the lowest potential to accumulate osseous remains, and the rate of accumulation varies based upon the type of den. The present research examines the remains accumulated by spotted hyenas in Masai Mara Cave, Masai Mara National Reserve, Kenya. The contents of this den were collected twice by the authors, with an 11-year span interceding. The taphonomic signatures of spotted hyena interaction with bone are presented, including species and skeletal element representation, breakage patterns, tooth marks, tooth puncture, edge polish, and gastric corrosion. Other taphonomic factors examined include rodent gnawing and weathering stage. The cave den assemblage was accumulated at a rate of 30.4 identified specimens and a minimum of 4.1 prey individuals per year. In addition, the osseous remains accumulated by spotted hyenas at multiple burrow dens within the Reserve were examined for taxonomic representation and multiple taphonomic parameters. Rates of accumulation at this type of den tend to be very low, due to differential usage by spotted hyenas and the more ephemeral nature of earthen dens.     

Taphonomy of the bones of rodents consumed by Andean hog-nosed skunks (Conepatus chinga, Carnivora,Mephitidae) in central Argentina

The Andean hog-nosed skunks (Conepatus chinga) are generalized consumers. Rodents are a substantial part of their diet. In order to learn about the effects of this predator on the bones of the prey they consume, the bone remains from scats collected in La Pampa, Argentina, were analyzed from a taphonomic point of view. Analysis confirms that C. chinga produces severe destruction of bone remains, mainly during the chewing process. This allows inclusion of this predator in the category of extreme modifier of the bones of its prey. Data presented here and their interpretation provide criteria to identify the intervention of this predator in archaeological and paleontological sites.     

The removal estimator: A ‘probable numbers’ statistic that requires no matching

The probable number of individuals (PNI) estimators all require that we be able to match left-right paired bones reliably. The problems of matching are outlined and ways of addressing them are reviewed. It is shown that archaeozoological studies in which reliable matching is difficult raise analytical problems similar to those faced by population biologists unable to use classical release-recapture methods. The removal estimator has been used to estimate the size of whale populations from incomplete census data. It can be generalized into archaeozoology to produce either a simple PNI statistic of the matching type, or a statistic that does not require reliable matching.     

Chemical changes in buried animal bone: Data from a postmedieval assemblage

Macroscopic chemical analysis of animal bone recovered from dated excavation contexts of known pH from Castle Bromwich Hall, West Midlands, UK, allows an assessment of the rate and effects of bone decomposition, and the evaluation of current models of chemical decay. The results show great variation, and it is suggested that factors such as mechanical disturbance have a more significant effect on the differential destruction of excavated bone assemblages than chemical decay. The implications of this conclusion for the attempted reconstruction of past faunas, diet and behaviour are summarized, recommending caution in the acceptance of assemblages as unbiased samples.     

A note on the use of temporal frequency distributions in studies of prehistoric demography

Temporal frequency distributions of archaeological sites and radiocarbon dates are commonly used as proxies for prehistoric population levels based on the assumption that more people create a stronger archaeological signal. While this assumption is certainly correct, we question whether relative frequencies of sites or dates observed from prehistoric contexts are necessarily linked to human demography. In this paper, we demonstrate that the typical positive curvilinear frequency distributions observed in archaeological contexts also regularly occur in paleontological and geological contexts and are thus likely caused by the operation of time-dependent destructive processes, what we call “taphonomic bias.” Using a simple model, which assumes a constant rate of site loss over time, we show how taphonomic bias can produce positive curvilinear frequency distributions through time even in cases of population stasis, decline, and fluctuation. We conclude that caution must be used when attempting to infer demographic trends from frequency distributions alone.     

Phytolith taphonomy: a comparison of dry ashing and acid extraction on the breakdown of conjoined phytoliths formed in Triticum durum

Durum wheat plants grown under optimum irrigation conditions in Jordan were processed in three different ways: 1) using a dry ashing method, 2) using acid extraction and 3) using both these methods, first dry ashing and then acid extraction. The aim was to determine if the laboratory processing method employed has an impact on the number of conjoined phytoliths recovered. This is important because it has been proposed that the number of conjoined phytoliths, or multi cells, can be an indication of water availability in arid and semi-arid regions (Rosen and Weiner 1994). The results showed that the processing method does have an impact on the resulting assemblage, with dry ashing producing a greater number of multi-cells than acid extraction. It is proposed that either the more violent oxidation of organic matter during acid extraction causes the breakup of conjoined phytoliths, or that the silica dehydrates during dry ashing resulting in a slight fusion between the individual phytoliths and hence more conjoined forms.     

Critical reassessment of putative Acheulean Porosphaera globularis beads

Excavations at Acheulean sites in northern Europe at the end of the 19th century have yielded fossil sponges belonging to the Late Cretaceous species Porosphaera globularis. The spherical morphology of these fossils, their small size, and the presence of a natural complete perforation in their center have led some archaeologists to interpret them as the oldest known beads. Others argue that the presence of these fossils at archaeological sites is due to natural processes. Re-examination of material collected during the 19th century has recently revived the bead interpretation. We tested the bead hypothesis by analyzing 13 samples of Porosphaera from nine sites in Britain and France. We conducted morphometric and microscopic analyses on specimens recovered from archaeological sites (n = 349), a natural geological sample, which was collected directly from Cretaceous strata (n = 352), and a sample from a Bronze Age burial (n = 43). Reappraisal of contextual data shows that the association of these finds with Acheulean artifacts is uncertain. Our results show that archaeological specimens are significantly different in size and perforation pattern from those of the natural geological sample. This may be due to size-sorting caused by sedimentary processes, size-selection by Palaeolithic people or by 19th century collectors. Modifications of the fossils' natural shape were detected on a few specimens in the form of localized abrasions and microchipping along the hole margins. A single specimen displays a facet close to the hole produced by grinding. The surfaces of these features exhibit a hue lighter than that observed on the remainder of the specimens indicating that they may be recent in origin and due to post-excavation and preservation treatment. However, this seems contradicted, for some specimens from Bedford, by the fact that according to Smith, W.G. [1884. On a Palaeolithic floor at North-East London. Journal of the Anthropological Institute of Great Britain and Ireland 13, 357–384] the specimens bearing microchipping and abrasions were found by him and “not touched or manipulated by the workmen”. We conclude that new excavations of these sites, involving systematic screening of sediments, are needed in order to attempt to solve the Porosphaera “mystery”.     

Why are cut mark frequencies in archaeofaunal assemblages so variable? A multivariate analysis

Cut mark frequencies in archaeological faunal assemblages are so variable that their use has recently created some skepticism. The present study analyses this variability using multivariate statistics on a set of 14 variables that involve differential skeletal element representation, fragmentation processes, carnivore ravaging impact, carcass size and tool type. All these variables affect the resulting cut mark frequencies reported in archaeological sites. A large sample of archaeofaunal assemblages has been used for this study. It was concluded that the best estimator of cut mark frequency in any given assemblage is the percentage of cut-marked long bone specimens (probably due to its better preservation than other anatomical areas), which is determined by fragmentation and carnivore ravaging. Carcass size and tool type also play a major role in differences in cut mark frequencies. Fragmentation is also a key variable determining the abundance of cut-marked specimens. It is argued that general cut mark percentages are of limited value, given the number of variables that determine them, and that a more heuristic approach involves quantifying cut marks in a qualitative manner.     

Fluvial transport of bovid long bones fragmented by the feeding activities of hominins and carnivores

This study explores the hydraulic transportability of bovid long bone fragments created through hominin and carnivore carcass consumption in order to determine the effect of fluvial transport on the incidences of hominin- and carnivore-induced bone surface modifications. Transportability was determined using an oval race track flume and 311 long bone fragments from modern control collections of hominin- and carnivore-modified bone. Results show that the fluvial transport of long bone fragments is predicted by animal size class and bone specimen size, as measured by maximum cortical thickness, maximum length, and maximum width. All of these variables can be measured on fossil specimens. Long bone portion (midshaft, near-epiphysis, and epiphysis) does not affect transport and hydraulic transport does not substantially modify the incidences of tooth, percussion, and cut marking in transported or lag assemblages in low energy fluvial environments. Implications of this study are: 1) animal size classes, and cortical thickness, length, and width of long bone fragments can be used to identify fluvial winnowing in fossil assemblages; 2) analyses concerning the relative timing of hominin and carnivore carcass consumption based on the proportions of long bone fragments bearing tooth, percussion, or cut marks can be meaningfully applied to fossil assemblages deposited in low-energy fluvial environments.