TESTING ANALOGICAL TAPHONOMIC SIGNATURES IN BONE BREAKING: A COMPARISON BETWEEN HAMMERSTONE‐BROKEN EQUID AND BOVID BONES

Current analogical data used to infer prehistoric human bone breakage rely on a plethora of experimental hammerstone‐broken bovid bone sets. Several criteria have been argued to be diagnostic of bone breakage by humans, among which the most important are: a specific range of broken specimens bearing percussion marks, a specific distribution of different percussion mark types, metric properties of notches, differential notch type distribution, and the angle of oblique breakage planes. The present work shows that those properties derived from the breakage of bovid bones cannot be universally applied to all types of animals. As an example, here it is experimentally demonstrated that hammerstone‐broken equid bones (with different thickness and structural properties compared to bovid bones) show different values in all these variables and some of them overlap with criteria documented in bones broken by static loading. This suggests that the agents of equid bone breakage are more difficult to identify, and that the number of variables that can be successfully used to that end is smaller than in bovid bones.     

A new experimental study on percussion marks and notches and their bearing on the interpretation of hammerstone-broken faunal assemblages

Preliminary experiments on bone breakage have shown the potential utility of quantifying some of its diagnostic features (percussion marks, percussion notches) for taphonomic inferences about human and carnivore involvement in bone breakage in faunal assemblages. The present study increases the range of experiments undertaken to understand the identification of hammerstone percussion (dynamic loading) and its differences from carnivore bone breakage through tooth pressure (static loading). This study contributes to a better understanding of frequencies of percussion marks, uncovers and quantifies those percussion marks that lack key diagnostic features to be identifiable and that could be mistaken with carnivore tooth marks, quantifies notch types, shows different size ranges for notches on bones from small and large fauna than previously reported, quantifies the proportion of notches bearing percussion marks, and introduces new size data for percussion (impact) flakes and percussion marks. Furthermore, all these variables have been applied to a dual experimental set: one experiment using non-modified hammerstones and another based on the use of modified hammerstones. Results vary considerably according to hammerstone type. Some of these taphonomic variables increase the range of equifinality when identifying marks and notches created by different human and non-human agents. This calls for further caution when using isolated variables and features rather than a holistic approach to make taphonomic inferences.     

Breaking Bones to Obtain Marrow: A Comparative Study between Percussion by Batting Bone on an Anvil and Hammerstone Percussion

The fat‐ and nutrient‐rich marrow of animal bones can be extracted using different techniques. Passive hammerstone percussion has been the primary focus of experimental bone breaking and the main analogy to understand archaeological bone breakage. Here, the term ‘passive’ is applied because the bone to be broken passively receives the impact from a hammerstone. In addition to this technique, there is another bone‐breaking method that also requires direct percussion, but in an active way. This method is percussion by ‘batting’, in which the bone is actively hit against an anvil until the bone breaks. This technique has rarely been considered at an experimental level and, therefore, has been omitted in the majority of the archaeological interpretations of faunal assemblages with pre‐use of fire technologies. In this study, we attempt to analytically characterize this type of bone‐breaking technique through a systematic comparison with hammerstone percussion. The applied statistical tests will allow us to distinguish some diagnostic modifications, such as the outlines of the fracture planes and the type of notches or their location with respect to the longitudinal axis of the bone. These features and their proportions allow the consideration of the use of this technique in Pleistocene anthropogenic faunal assemblages.     

Carnivore competition, bone destruction, and bone density

In carnivore-modified archaeofaunal assemblages it is important to evaluate the degree to which carnivores have overprinted hominin behavioral signals. To examine the signals of increased competition for discarded bone, we present controlled experimental data on 33 simulated archaeological sites subjected to secondary consumption by spotted hyenas. We examine the relationship between competition, as measured by controlled numbers of hyenas and limb bones, and resultant levels of destruction and correlations between long-bone portion survivorship and bone density. Our results indicate that levels of destruction are equivalent regardless of the numbers of hyenas or long-bones included in the experimental assemblages. Correlations between long-bone epiphyseal and near-epiphyseal portions and bone density, however, do provide an indication of the level of competition. Results from the experimental study are used to highlight divergent levels of carnivore competition for hominin-discarded bone at the Plio-Pleistocene localities FLKN-Zinjanthropus and FLKN levels 1–2 from Olduvai Gorge, Tanzania.     

Actualistic research into dynamic impact and its implications for understanding differential bone fragmentation and survivorship

The relationship between bone mineral density and archaeological bone survivorship has played a critical role in zooarchaeological and taphonomic studies in recent decades. Numerous studies have suggested that higher-density skeletal element portions survive more frequently than lower-density element portions when archaeological assemblages are affected by some taphonomic processes. Interpretations of density mediated destruction have become commonplace in the archaeological literature, and are often used to explain the absence of certain bone elements and element parts in zooarchaeological assemblages. This study explores the effects of rockfall on bovid elements in varied environmental conditions and the differential survivorship of their element parts, and has implications for understanding the taphonomic processes through which bones are subjected to dynamic loading. Actualistic rockfall experiments conducted on twelve samples of frozen, fresh, and semi-dried bovid bones reveal that the generally low-density epiphyseal ends of bone elements resist fracture and analytical deletion with more frequency than the higher-density diaphyses. This evidence suggests that bone density does not correlate with likelihood of breakage or effective archaeological “destruction” when rockfall and other processes that result in dynamic impact are in action. While this research does not question the relationship between bone mineral density and the likelihood for archaeological survivorship as the result of some taphonomic processes, it presents one specific set of taphonomic processes that result in the differential survivorship of low density bone elements parts and the fragmentation and destruction of higher density element parts. This research presents evidence that shows that dynamic impact is a process capable of fragmenting and sometimes destroying high-density elements while low-density elements survive.     

A taphonomic study of bone modification and of tooth‐mark patterns on long limb bone portions by suids

This work presents new taphonomic data on bone modification by suids, including domestic pig, wild and hybrid boars. The intense modification undergone by bones from animals smaller than 100 kg is shown, together with a more moderate modification on bones from larger animals. Both the ravaging pattern (with preferential deletion of cancellous tissue) and the tooth‐marking frequencies are similar to those documented among hyenas and dogs when having primary access to complete bones. A dual‐patterned experimental model consisting of the interaction of humans and suids was also considered. Here it is shown how suid modification of hammerstone‐broken bone assemblages is different from that documented among canids and hyaenids, as experimentally replicated. These results increase the number of non‐anthropogenic bone‐modifying agents and posit new issues on equifinality processes. Copyright © 2008 John Wiley & Sons, Ltd.     

An investigation of cortical bone loss and fracture patterns in the neolithic community of Çatalhöyük,Turkey using metacarpal radiogrammetry

Bioarchaeologists have conducted numerous studies on human skeletal remains using metacarpal cortical bone radiogrammetry. This method allows cortical thickness of the second metacarpal to be quantified. As a sensitive index of bone health metacarpal cortical thickness is evaluated in the context of functional adaptations, growth, ageing and bone loss in osteoporosis, as well as used as a reliable indicator of fracture risk. The focus of this study is an examination of the widely used calculation that expresses second metacarpal cortical bone values, followed by an examination of age and sex-related patterns of cortical bone loss and skeletal fragility fracture in a Neolithic archaeological skeletal sample from Çatalhöyük, Turkey. Using metacarpal radiogrammetry, 49 adult metacarpals (f = 27 m = 22) were examined. Data were collected for size variables, length (L) and total bone width (TW) as well as quantity variables, medullary width (MW) and cortical thickness (CT). These parameters were then used to calculate the widely used cortical index (CI) and two new indices expressing medullary width and cortical bone thickness in relation to length (medullary width index, MWI and cortical thickness index, CTI). The ratios were then used to explore age- and sex-related cortical bone loss and fragility fracture patterns amongst the inhabitants of Çatalhöyük. Çatalhöyük males and females demonstrate an inverse relationship where CTI decreases as age and MWI increase. Analyses indicate statistically significant age-related change in MWI amongst the oldest females. Despite age-related loss of bone, no typical fragility fractures are observed. We discuss the role of ageing and lifestyle factors at Çatalhöyük that may have been beneficial to skeletal health and a reduction in the risk of fragility fracture.     

Intrataxonomic variability in metapodial and femur bone density related to age in guanaco (Lama guanicoe). Zooarchaeological and taphonomical implications

The aim of this paper is to present new information about bone mineral density (BMD) variability in guanaco (Lama guanicoe), a South American wild camelid; while taking into account its ontogenic development. The importance of considering intrataxonomic variability in bone density related to age for constructing zooarchaeological indices and applying them to archaeological assemblages is also discussed. The results presented here were developed from a large sample of 46 metacarpals and 45 femurs of modern guanacos, ranging in age from ca. 6 months of gestation to 12 years. Bone structural densities were measured using a biphotonic X-ray densitometer, DEXA method, Norland EXCELL and the bone mineral content (BMC) of each scanned portion or complete element was divided by its volume, which was obtained independently by water displacement. Our results indicate that the bone density of each anatomical unit is highly variable, even among individuals of the same species. According to metacarpals data, age is an important factor affecting BMD. Moreover, our study shows that the density ranges of different skeletal elements can overlap, suggesting that it is not possible to predict that a certain element is always denser than another one. Finally, we present new evidence about the potential age-related taphonomic bias in faunal assemblages, indicating that meanwhile some skeletal elements show clear differences in their density between their fused and unfused state (metacarpal) other do not (femur).     

FOCUS: on the use of the petrous bone for estimating cranial abundance in fossil assemblages

Low representation of braincase bones in zooarchaeological assemblages suggests that skulls have been intensively processed by Levantine Epipalaeolithic foragers; most cranial elements are often unidentifiable and are considered poor candidates for quantifying crania. In contrast, the petrous bone is usually found complete, and was found to be easily identifiable to body size category. Use of the petrous bone in fossil assemblages analyses leads to better estimation of the occurrence of cranial elements, and thus of skeletal part representation. We therefore suggest use of the petrous bone for detecting bone destruction and selective transport in faunal assemblages.     

Experimental patterns of hammerstone percussion damage on bones: implications for inferences of carcass processing by humans

The common occurrence of hammerstone percussion damage (pits, striae, notches and impact flakes) on the fossil limb bones of ungulates indicates that marrow extraction has been an important component of hominid butchery for over two million years. Beyond this level of basic inference, it would be behaviorally informative if three deeper aspects of marrow harvesting were understood more clearly: (1) whether inter-element patterns of bone fragmentation vary when processing intensity is held constant; (2) whether butcher investment in marrow extraction correlates positively with the number of percussion marks generated; (3) whether taphonomic effectors can be identified based on percussion mark morphology, frequency and placement. Some experimental work has been conducted previously in service of exploring these questions, but we set out here to address them explicitly through the analysis of a large sample of white-tailed deer (Odocoileus virginianus) limb elements fractured by hammerstone percussion. Our results indicate that (1) measures of bone fragmentation, which supposedly reflect processing intensity, are highly contingent on the research question being posed. This stresses the fact that researchers must be explicit in their definition of processing intensity. (2) In addition, hypothesized covariance between number of hammerstone blows and percussion mark frequencies are not met in our sample, corroborating previous conclusions of a lack of covariance between cutting strokes and cutmark frequencies. These results highlight the contingent nature of butchery mark production, and emphasize the need to investigate carcass resource exploitation by posing questions that do not rely on mark frequencies, but instead utilize other zooarchaeological measures. (3) Finally, our results—showing high incidences of impact notches and flakes created by direct anvil contact and “anvil scratches” created by direct hammerstone contact—suggest caution in using specific categories of percussion damage to infer their taphonomic effectors.     

The Role of Bubo virginianus magellanicus as Rodent Bone Accumulator in Archaeological Sites: A Case Study for the Atuel River (Mendoza,Argentina)

Micromammalian bone assemblages from modern pellets of the strigiform Bubo virginianus magellanicus, from the upper Atuel River (southern Mendoza, Argentina), were taphonomically analysed. The results allow us to place B. v. magellanicus in the category of intermediate modification (Category 2). This sample has also been compared with results from other members of this genus, in order to classify B. v. magellanicus as a taphonomic agent. The participation of the Bubo species in archaeological accumulations has been documented, but in Argentina, the role of B. v. magellanicus has been reported up to the present. It is partly because of the sequence of one archaeological site in the south of Mendoza Province called Laguna El Sosneado‐3 (LS‐3). However, considering the absence of a current taphonomic model of this owl, this participation was mentioned as a hypothesis. In the current investigation, archaeological and modern samples have been compared. The results indicate that the skeletal element assemblages recovered from LS‐3 were accumulated by strigiform birds. Taphonomical evidence of light modifications on units I and IV indicates that Tyto alba (Category 1) was probably the main species involved in these units, whereas the taphonomical evidence on skeletal element assemblages recovered from units II and III suggests the action of a strigiform with a major category of modification such as B. v. magellanicus. Copyright © 2015 John Wiley & Sons, Ltd.     

Human digestive effects on a micromammalian skeleton

This study describes the results of an experiment involving the consumption of a skinned, eviscerated, and segmented insectivore by an adult human male. Bone remains from recovered faecal contents are examined for skeletal element representation, breakage and digestive damage. Detailed examination of each category suggests severe skeletal attrition which is comparable to, and at times in excess of, the damage exhibited in microvertebrate skeletal accumulations originating from the scats of small mammalian carnivores.     

A new element of trampling: an experimental application on the Level XII faunal record of Bolomor Cave (Valencia,Spain)

In Level XII of Bolomor Cave (Valencia, Spain) modifications have been observed on some of the bone fragments that make up the faunal record. These alterations consist of small notches located on the oblique fracture angles of some bones. The frequency at which these modifications appear in the assemblage has obliged to plan several experimental series to know the process that causes them. To be more exact, this study aims to verify whether these small chips are the result of trampling. For this purpose, two experimental series have been developed. The first of which has the objective of differentiating between the variables related to the original state of the bone (green, semi-dry and dry) and the second is aimed at reproducing the modifications observed in the archaeological set, taking into account the data obtained in the previous series. Following these experiments, the appearance of small notches is observed on the oblique fracture angles of some bones in semi-dry state. These resulting chips are similar to those documented in Bolomor Cave, Level XII. Therefore, it is deduced that trampling is the principle cause of these modifications in the bone record. This fact has important archaeological implications, as the spatial distribution of this modification can provide information about the intrasite movements of the human groups.     

Skeletal element abundances in archaeofaunal assemblages: economic utility,sample size,and assessment of carcass transport strategies

Economic utility indices provide a means of interpreting butchery and transport decisions reflected in the relative abundance of skeletal elements. Because of destructive taphonomic processes, interpreting skeletal element abundances in terms of carcass transport strategies requires that faunal analysts consider only those elements which accurately reflect their original abundances following human discard. In this study we use resampling techniques to examine the impact of sample size on correlations between high-survival skeletal element frequencies and economic utility in four simulated population assemblages reflecting distinct carcass transport strategies. Correlations alone do not accurately reflect the true relationship between bone abundance and economic utility as particular transport strategies have a tendency to generate high frequencies of Type II errors as sample size decreases. We show that the Shannon evenness index can be used as a quantitative means of distinguishing between bone assemblages characterized by subtle variations in skeletal element abundances. The evenness index can also be used to evaluate whether observed correlations reflect sampling error. Results from our simulations are applied to three published faunal assemblages to evaluate likely carcass transport strategies.     

Reconsideration of criteria for differentiating faunal assemblages accumulated by hyenas and hominids

Zooarchaeologists have established several criteria for differentiating hominid‐ and hyena‐derived faunal assemblages. In some cases, however, the patterns of skeletal part representation and bone surface modification on which these criteria are ultimately based have been observed in fossil bone assemblages of unknown origin, rather than in modern assemblages of known origin. When the proposed criteria are evaluated within an actualistic framework, only three are able to differentiate between hominid‐ and hyena‐created faunal assemblages. I suggest that only these three criteria—proportions of carnivores to ungulates in the assemblage, the preserved condition of long bone specimens (either as whole cylinders or as splintered shaft fragments), and the types of bone surface modifications—should be retained as important factors in a diagnosis of the ancient bone‐collector. The remaining four criteria—the relative proportion of horn pieces in the assemblage, the relative representation of podial bones, the relative representation of small and large bovid skeletal parts, and bovid mortality profiles—are not relevant or applicable to the problem of differentiating hominid‐ from hyena‐derived faunal assemblages. Copyright © 2002 John Wiley & Sons, Ltd.     

Tracking changes in bone fracture morphology over time: environment, taphonomy, and the archaeological record

Zooarchaeologists have often employed studies of bone fracture morphology as a means of understanding past human cultural activity, and various methodological approaches have been developed for analyzing archaeological broken bone assemblages. It is widely understood that bones degrade over time, however, few studies have attempted to define and quantify the rate at which bones degrade and fracture morphologies change. This study examines degradation in frozen bones (−20 °C) and bones exposed to hot (40 °C) dry conditions. These two simulated environmental conditions represent extreme real-world climates, and allow for an actualistic understanding of the rates of degradation that bones experience in nature. When frozen, bones degrade slowly but significantly, and demonstrate measurable differences in samples frozen for 1, 10, 20, 40, and 60 weeks. In hot, dry conditions, bones degrade very quickly, and demonstrate measurable differences after 1, 3, 7, 14, and 21 days. These data allow for a more detailed understanding of the relationship between the cultural and natural processes that result in bone fracture, and the time period during which bones can be expected to maintain fresh fracture characteristics. This research also has implications for understanding human subsistence and survival strategies and for interpreting the archaeological record.     

Food for thought: using game cameras to better understand the movement of bones by scavenging in archaeological faunal assemblages

This paper questions our understanding of the movement of bones by animal scavengers in the archaeological record. Since assumptions regarding the effects of animal scavenging shape final interpretations of skeletal element frequencies in archaeological faunal assemblages, they are important for our understanding and reconstruction of ancient human behaviour. The results of a 4-year actualistic kangaroo scavenging study from Australia are used to question our understanding of the movement of the bone by contrasting visual data captured by motion-activated digital game cameras with traditional taphonomic studies using skeletal element frequencies. Game cameras are commonly used by ecologists to capture the behaviour of living species but have not yet been used in experimental archaeology where visually documenting animal scavenging behaviour can be used to understand the movement of carcasses and individual bones. Results suggest that traditional zooarchaeological analyses may not be accurate indicators of hunted versus scavenged prey in archaeological faunal assemblages. Moreover, they most certainly fail to document the entire suite of animals scavenging a carcass. These implications are discussed with particular reference to the ability to definitively ascertain the role of humans in the megafaunal extinction debate in Australia.     

Body Part Representation,Fragmentation and Patterns of Ertebølle Deer Exploitation in Northwest Zealand,Denmark

The faunal assemblages from Asnæs Havnemark, Fårevejle and Trustrup, located in northwest Zealand, Denmark, yielded extensive yet substantially fragmented bone material dating predominantly to the late Mesolithic Ertebølle culture, ca. 5400–3950 cal BC . This paper presents a combined assessment of skeletal part representation of red deer (Cervus elaphus) and roe deer (Capreolus capreolus) from these three sites in conjunction with quantification of overall fragmentation data for the assemblages. These data indicate that the observed pattern of skeletal part abundance is most consistent with a pattern of density‐mediated skeletal attrition, and therefore the whole carcasses were initially deposited. Deer were not part of a logistic exploitation strategy at these sites. This indicates variability during the Ertebølle period not only in which resources were exploited, but in how these resources were processed. Copyright © 2013 John Wiley & Sons, Ltd.     

Taphonomic Analysis of Micromammal Remains from Striped Owl (Pseudoscops clamator) Pellets in Northeastern Buenos Aires Province,Argentina: Implications for Archaeological Sites Formation

The main objective of this study was to determine the taxonomic and taphonomic characteristics of the micromammal remains recovered from pellets of Pseudoscops clamator (striped owl), collected at three localities in northeastern Buenos Aires Province, Argentina (Punta Lara Natural Reserve, 34°49'02,6''S, 58°03'03,9''W; Costanera Sur Ecological Reserve, 34°36'6,44" S, 58°21'33,22" W; Los Robles Park, 34°40'22,03''S, 58°52'18,88''W). The main taphonomic variables (e.g. evidence of digestive action, breakage patterns and relative abundance of skeletal elements) suggest that this owl mainly produces intermediate to moderate modification. On the other hand, P. clamator preyed mainly upon large‐sized (>150 g) micromammals (e.g. Lutreolina crassicaudata, Cavia aperea, Holochilus brasiliensis and Rattus sp.), and to a lesser degree on medium‐ (50–150 g) and small‐sized species (<50 g) (e.g. Scapteromys aquaticus, Calomys sp., Oligoryzomys flavescens, Akodon azarae and Mus musculus). Fossil assemblages with a dominance of large‐sized micromammals are commonly associated with humans as agents of accumulation. However, this study demonstrates that this owl produces assemblages with abundant large‐sized micromammals, which introduces an equifinality problem. In that sense, digestive corrosion marks, breakage patterns and the relative abundance of skeletal remains are the main attributes to differentiate P. clamator from humans, as agents of accumulation. Finally, our results might serve as an analytical model for the taphonomic interpretation of the fossil record of micromammals from paleontological and archaeological sites, which fall within the distributional range and habitat of P. clamator. Copyright © 2013 John Wiley & Sons, Ltd.     

Micromammal taphonomy of el-Wad Terrace,Mount Carmel,Israel: distinguishing cultural from natural depositional agents in the Late Natufian

A taphonomic analysis of micromammal remains from the Late Natufian deposits of el-Wad Terrace, Mount Carmel, Israel, was conducted in order to test the long-standing premise of owl deposition as the primary accumulating agent. The inferred taphonomic sequence was modeled within an actualistic (recent) comparative framework incorporating a locally derived barn owl pellet collection and an off-site control assemblage of micromammal remains from the cliff overhanging the terrace. The sequence was reconstructed based on multiple types of recorded taphonomic data, comprising skeletal modifications (breakage, digestion, weathering, gnawing, and charring) and age structure. Evidence for post-depositional processes including fluvial transport, trampling, and weathering was isolated and consequently the typical owl imprints were traced through the two actualistic and the archaeological assemblages. Based on the extent of breakage and patterning in skeletal element frequencies it was also possible to scale the preservation potential of primary data in el-Wad Terrace as a discrete site type, intermediate between true cave and open-air depositional environments. Verifying the role of owls as principal agents of accumulation of the el-Wad Terrace micromammal remains enabled the detection of two minor superimposed cultural patterns: consumption of mole rats (Spalax sp.) by the Natufians and commensalism of mice (Mus spp.).