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.     

Bone surface modifications in zooarchaeology

Cutmarks made by stone tools, conchoidal flake scars from hammerstone percussion, carnivore tooth marks, striations from sedimentary abrasion, and other surface modifications on bones from archaeological sites constitute a crucial body of evidence for investigating the role of human behaviors and of nonhuman taphonomic processes in site formation. This paper describes the various kinds of bone surface modifications produced by humans and by nonhuman processes and assesses the current status of bone surface modification studies with regard to such issues as the need for greater analytical standardization, the selection of instruments for examining bone specimens, tactics for identifying the origins of marks on bones, and strategies for inferring human behaviors.     

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.     

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.     

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.     

New analytical methods for comparing bone fracture angles: A controlled study of hammerstone and hyena (Crocuta crocuta) long bone breakage

Accurate interpretation of the cause and timing of bone breakage is essential for understanding the archaeological record. However, many variables potentially influencing break morphology have yet to be systematically explored. Focusing primarily on hammerstone breakage, we introduce new analytical methods for comparing fracture angles using the absolute values of the angle from 90°. We systematically control for intrinsic variables such as taxon, skeletal element, limb portion and skeletal age. We also compare experimental assemblages of femora broken by hammerstone and spotted hyena (Crocuta crocuta). We show that fracture angles are influenced by breakage plane, skeletal element and limb portion. While the latter two have been suggested before, this is the first time the differences have been quantified. We suggest that researchers stratify their assemblages by these variables if they are using fracture angles in analyses. At the assemblage level, hyenas created more oblique fracture angles on oblique breaks than did hammerstones.     

Ascertaining an agent: using tooth pit data to determine the carnivore/s responsible for predation in cases of suspected big cat kills in an upland area of Britain

The identification of the involvement of a particular carnivore in the modification of bone assemblages concerns a number of fields of research including archaeological and palaeontological enquiry. Taphonomy provides a methodology by which bone assemblages can be analysed and interpreted and this is more often undertaken with archaeological or palaeontological assemblages. A taphonomic analysis is undertaken here in order to determine the perpetrator of predation attacks on domestic stock from a modern-day setting. Recently reported techniques using tooth marks preserved on bone surfaces made by known carnivores are successful at determining some class sizes of predators and are used here to determine the perpetrator(s). Although a class size of carnivore is readily identified by this methodology, a particular carnivore taxon is not. Tooth morphology and dental configuration are reported here as better criteria for identifying a particular taphonomic agent. Tooth pit dimensions are used here to identify the class size of carnivores involved, and tooth morphology and cusp spacing to suggest a medium sized felid and fox as taphonomic agents. The identification of the medium-sized felid may support observations and reports of alleged “big” cat kills in the area. The study has important implications for the interpretation of fossil sites where felids may have been involved in the modification of animal carcasses but are archaeologically invisible in terms of their fossil remains.     

Pits and pitfalls: taxonomic variability and patterning in tooth mark dimensions

Archaeologists use experimentally derived tooth mark frequencies, locations, and size data to infer (a) the extent of carnivore involvement in the formation and modification of faunal assemblages, (b) the size classes of predators marking those assemblages, and (c) whether hominins accessed fleshy or defleshed carcasses (Blumenschine and Pobiner, 2007; Dominguez-Rodrigo et al., 2007). These inferences are often debated in part because frequency counts can vary widely among observers and because the carnivore taxa for which tooth mark dimensional data are available are limited. This study contributes to the body of actualistic/experimental tooth mark data and presents a methodology for collecting these data. We offer a greatly simplified method that may encourage others to collect and quantify tooth mark dimensions. We present dimensional data from feeding experiments with 16 omnivore and carnivore species of known age and mass, ranging in size from skunks to tigers, significantly expanding the taxonomic and size range of carnivores for which we have tooth pit data. Our results demonstrate considerable, but not complete, overlap in tooth pit dimensions among size, class, and taxon. Tooth mark dimensions on epiphyses and metaphyses were relatively strongly correlated with body mass, whereas diaphyseal tooth marks exhibited the weakest correlation. Human consumption of animal tissue produced tooth marks comparable in size to medium felids and small canids, suggesting the possibility that some tooth marks on Early Stone Age (ESA) faunal assemblages could, as suggested by Oliver (1994), result from small carnivore and/or hominin consumption.     

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.     

An experimental study of large mammal bone modification by crocodiles and its bearing on the interpretation of crocodile predation at FLK Zinj and FLK NN3

The taphonomic signature of crocodiles as agents of bone modification has been previously identified by specific tooth mark types (e.g., bisected pits) and by a conspicuous presence of these marks: more than 75% of bones modified by crocodiles bear at least one of these distinctive marks. Therefore, crocodile tooth-marking would be notably prevalent in bone assemblages resulting from crocodile predation and active scavenging. The present study contributes to refine this diagnosis by showing greater variability of these types of marks, a different degree of tooth-marking intensity, and a somewhat different distribution of tooth-marked elements according to skeletal parts from previous experiments with crocodiles. Some of these differences are due to different experimental variables and conditions and this highlights the need to understand behavioral variability in crocodile ecological settings. This variability in crocodile tooth-marking probably results from several as-yet-inadequately measured behavioral and ecological factors, such as intensity of feeding competition and differences between male and female crocodile feeding behaviors, among others. Furthermore, this study also contributes to a better definition of the microscopic criteria that can be used to distinguish crocodile-inflicted marks from other types of bone surface modifications. In light of these and previous experimental frameworks, we reevaluate the application of these analogs to modifications documented in hominin fossils from Olduvai Gorge (OH8 and OH35) and the resulting inferences about the hazard posed by crocodiles on the paleolandscape where FLK North North and FLK Zinj (Bed I) were formed. The taphonomic analysis also shows that Olduvai OH8 and OH35 were probably not preyed upon by crocodiles. It is concluded that no tangible evidence can be used to support the interpretation that OH35 was modified by crocodiles and that the overall presence of crocodiles in FLK North North and FLK Zinj was rather marginal, based on the virtual absence of crocodile-modified bones in both archaeofaunal assemblages.     

Identifying the Involvement of Multiple Carnivore Taxa with Archaeological Bone Assemblages

Information on the number of carnivore taxa that were involved with archaeological bone assemblages is pertinent to questions of site formation, hominid and carnivore competition for carcasses and the sequence of hominid and carnivore activity at sites. A majority of early archaeological bone assemblages bear evidence that both hominids and carnivores removed flesh and/or marrow from the bones. Whether flesh specialists (felids) or bone-crunchers (hyaenas), or both, fed upon the carcasses is crucial for deciphering the timing of hominid involvement with the assemblages. Here we present an initial attempt to differentiate the tooth mark signature inflicted on bones by a single carnivore species versus multiple carnivore taxa. Quantitative data on carnivore tooth pits, those resembling a tooth crown or a cusp, are presented for two characteristics: the area of the marks in millimetres, and the shape as determined by the ratio of the major axis to the minor axis of the mark. Tooth pits from bones modified by extant East African carnivores and latex impressions of tooth pits from extinct carnivore species are compared to those in the FLK Zinjanthropus bone assemblage. Data on tooth mark shape indicate greater variability in theZinj sample than is exhibited by any individual extant or extinct carnivore species in the comparative sample. Data on tooth mark area demonstrate that bone density is related to the size of marks. Taken together, these data support the inference that felids defleshed bones in the Zinj assemblage and that hyaenas had final access to any grease or tissues that remained.     

The Taphonomy of the Final Middle Stone Age Fauna from Sibudu Cave,South Africa

This study applies a taphonomic analysis to the final Middle Stone Age faunal assemblage from Sibudu Cave, South Africa, by assessing bone surface modifications, breakage patterns and skeletal element abundances. Cut marks, percussion marks, severe fragmentation and the high frequency of burned bone combine to demonstrate that human behaviour was the principal agent in the assemblage's formation. These results are consistent with previous research on earlier occupations of Sibudu during the Middle Stone Age. Moreover, this assemblage is proposed to reflect regular site maintenance and cleaning. This conclusion is consistent with previous research that demonstrates systematic site maintenance during the Middle Stone Age at Sibudu and emphasises this behaviour as being a consistent activity for Middle Stone Age foragers. Copyright © 2013 John Wiley & Sons, Ltd.     

Changing patterns of carnivore modification in a landscape bone assemblage, Amboseli Park, Kenya

This study compares the landscape-scale taphonomic signal of carnivore modification to the surficial bone assemblage in Amboseli Park, Kenya as it was in 1975 and 2002–2004. Change in predator abundances over time provides a means of assessing the taphonomic signal of carnivore-mediated bone consumption and destruction under differing ecological conditions and varying levels of conspecific competition for resources. The landscape assemblage indicates taxonomic variation in the patterning of carnivore modification to ungulates of different size classes as well as within equivalent size classes. Analyses of long bone elements indicate that the differential destruction of limb ends and the strength of the correlation between limb end abundance and bone mineral density provide an indication of the intensity of carnivore modification to a faunal assemblage. The ability to infer levels of carnivore modification based on limb elements can provide faunal analysts with the tools to determine whether the taphonomic signals in the fossil record relate to carnivore modification, hominin transport of appendicular elements, or both.     

A cautionary note on the use of captive carnivores to model wild predator behavior: a comparison of bone modification patterns on long bones by captive and wild lions

A study with wild lions in Tarangire National Park (Tanzania) and with captive lions in Cabárceno Reserve (Spain) has yielded two different bone modification patterns, probably as a result of the differences in environmental contexts. Captive lions have modified bones more intensively, both in the form of total number of tooth-marked bones and number of tooth marks per tooth-marked bone, probably because of stereotypic behaviors. This emphasizes the importance of environmental contexts to understand carnivore behavior and their resulting bone modification patterns. It also shows that analogical models based on experiments carried out with captive carnivores may be biased and inadequate as proxies for wild carnivore bone modification behaviors.     

Taphonomic studies with wild brown bears (Ursus arctos) in the mountains of northern Spain

In this work we present data obtained from experiments with wild brown bears from the Cantabrian Mountains in northern Spain. Our results show that wild brown bears do not take carcasses to their dens, but can displace them by tens of meters before eating them, and the remains can become dispersed some meters around the place where the carcass is consumed. The long bones of large-sized carcasses show no fractures, but they do show tooth marks (scores, pitting, punctures and furrowing) especially on the cancellous bone of the epiphyses. Ribs and vertebrae show fractures and furrowing. The innominate also shows furrowing on cancellous bone of the ilium and ischium. The results of this study are in agreement with previous work and also shed some light on the behavior of this carnivore in the wild. The data gathered are of great importance when interpreting paleontological and archaeological sites where the bear is a likely taphonomic agent.     

A study of dimensional differences of tooth marks (pits and scores) on bones modified by small and large carnivores

The use of tooth mark sizes to infer carnivore types when analyzing the modification of faunal assemblages has been criticized on the base of intense overlap in tooth mark size among differently sized carnivores. The present study analyzes this overlap and presents some critical explanations for it. This work is based on the largest collection of tooth pit dimensional data collected to date for some of the most relevant carnivore types. The study empirically shows that small and large carnivores can be clearly differentiated when using tooth pit size, with a higher discrimination when using tooth marks on dense shafts than on cancellous ends. It is argued that most previous studies of tooth mark sizes have reproduced a higher overlap probably because sample sizes were small, and experiments were carried out using small carcasses (which require a smaller bite force) or for a combination of factors.     

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.     

Taphonomy of ungulate ribs and the consumption of meat and bone by 1.2-million-year-old hominins at Olduvai Gorge,Tanzania

The phenomenon of equifinality complicates behavioral interpretations of faunal assemblages from contexts in which Pleistocene hominins are suspected bone accumulators. Stone tool butchery marks on ungulate fossils are diagnostic of hominin activities, but debate continues over the higher-order implications of butchered bones for the foraging capabilities of hominins. Additionally, tooth marks imparted on bones by hominins overlap in morphology and dimensions with those created by some non-hominin carnivores, further confounding our view of early hominins as meat-eating hunters, scavengers or both. We report on the manual/oral peeling of cortical layers of ungulate ribs as taphonomically diagnostic of hominoid/hominin meat- and bone-eating behavior that indicates access to large herbivore carcasses by hominins at the site of BK, Olduvai. Supporting these inferences, we show that certain types of rib peeling damage are very rare or completely unknown in faunas created by modern carnivores and African porcupines, but common in faunas modified by the butchery and/or consumption activities of modern humans and chimpanzees, during which these hominoids often grasp ribs with their hands, and then used their teeth to peel strips of cortex from raggedly chewed ends of the ribs. Carnivores consume ungulate ribcage tissues soon after kills, so diagnostic traces of hominin butchery/consumption on ribs (i.e., peeling and butchery marks) indicate early access to ungulate carcasses by BK hominins. Tooth marks associated with the peeling and butchery marks are probably hominin-derived, and may indicate that it was not uncommon for our ancestors to use their teeth to strip meat from and to consume portions of ribs. Recognition of rib peeling as a diagnostic signature of hominoid/hominin behavior may also aid the search for pre-archaeological traces of hominin meat-eating.     

Avian taphonomy: observations at two Magellanic penguin (Spheniscus magellanicus) breeding colonies and their implications for the fossil record

Actualistic studies on vertebrate taphonomy have centred on mammals, and to a much lesser extent on flying birds. Members of the Spheniscidae are anatomically specialized making it problematic to make direct inferences from previous taphonomic work. Modern bone assemblages from two Spheniscus magellanicus breeding colonies on the southern Atlantic coast of continental Patagonia, Argentina, were surveyed on foot along linear transects, and features were determined that are useful in interpreting the fossil record. Present day bone accumulations have specific properties resulting from penguin anatomy and osteology as well as from the composition of the vertebrate community and regional environmental conditions. Most salient are the high spatial density of bones, the dominance of Spheniscidae remains over those of other vertebrates, the high percentage of disarticulated bones, the predominance of limb bones, the low frequencies of carnivore bone modifications, and the abundance of fractured bones. Many of these features observed in the modern assemblages can be identified in fossil avian bone deposits.     

Evidence of butchery and hominid activities at Torralba and Ambrona; an evaluation using microscopic techniques

Torralba and Ambrona have been interpreted as butchery sites for many years, a contention recently challenged; natural death or carnivore activities are invoked as an alternative explanation. Scanning electron microscopy (SEM) of bone surface replicas distinguishes among hominid-produced cutmarks, carnivore tooth scratches, and other types of bone damage. A sample of 102 replicas, comprising the most likely cutmarks on a combined sample of roughly 3000 fossils from Torralba and Ambrona, were scanned to determine the major agent of damage. Microscopically verified cutmarks are present, but rare, occurring in less than 1% of the bones in the combined sample. Carnivore tooth scratches are comparably rare. In contrast, evidence of sedimentary abrasion, which obliterates the diagnostic features of cutmarks, is present on nearly every bone from Torralba and Ambrona. It remains unresolved whether cutmarks were initially more common on these bones and were subsequently obliterated by abrasion, or whether the incidence of cutmarks was always low. These data demonstrate clearly that hominids and carnivores each damaged some bones at Torralba and Ambrona, but the frequency of each type of mark is too low to confirm strongly the interpretation of these sites as either butchery or carnivore remains.