Experimental effects of bone size and temperature on bone diagenesis

In the ground, bone undergoes chemical and physical changes which affect its preservation. This fact has important implications for dating and other analytical procedures involving bone, as well as faunal analysis where differential preservation of bones of different species may affect conclusions regarding the relative significance of an animal to the economy of a given society. The diagenic processes in bone range from minor changes in the bone protein to complete structural and chemical breakdown.Using fresh cow bone, we conducted laboratory experiments which simulate the effect of temperature and bone size on the rate and nature of bone disintegration in archaeological sites. Temperature influences the rate of chemical change, and bone size and density affect the accessibility of the molecular constituents of bone to extrinsic chemical reactions. These findings clarify the importance of two well-known concepts in bone taphonomy. (1) The rate of chemical breakdown in bone tissues is related to the proximity of a given unit of tissue to the bone surface. This means that, in archaeological bone samples, tissue near the surface may be different chemically from tissue away from the surface and great care is necessary in choosing and preparing bone samples for analytical procedures. (2) In general, small bones are not as well preserved as large bones, therefore small animals are likely to be underrepresented in faunal assemblages.     

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.     

Fluvial spatial taphonomy: a new method for the study of post-depositional processes

Traditional taphonomic analyses do not consider the emergent properties resulting from the relationship of variables. Several of these emergent properties are expressed spatially. Here, we present a spatial taphonomic approach to the understanding of post-depositional processes affecting experimental assemblages modified by fluvial currents. Spatial statistical methods are a great tool to understand how different taphonomic variables relate at a spatial scale. The results of the application of this method to bone assemblages affected by low- and high-energy flows show the loss or modification of most of the original spatial taphonomic relationships. It also shows the degree of bone loss according to element, anatomical section and bone structure, and shape types. Anisotropy is identified in both experimental contexts. These results add new criteria to assess the impact of water flows in bone assemblages and contribute to define the properties of lag 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.     

Examining criteria for identifying and differentiating fossil faunal assemblages accumulated by hyenas and hominins using extant hyenid accumulations

Numerous authors have put forth criteria for distinguishing between assemblages collected by hyenas and hominins. Of the seven most recognised criteria used to distinguish hyenid from hominin assemblages, it has recently been suggested that four be rejected and three retained. The four rejected criteria are: an excessive proportion of horns and horn cores in hyena accumulated assemblages; the absence of small, hard, compact bones; mortality profiles; and the ratio of cranial bones to postcranial bones. The three criteria previous researchers suggested be retained are: a carnivore MNI ratio of ≥20%; an abundance of cylinder fragments; and hyena‐inflicted damage upon the bones. In this examination of over 27,000 faunal remains associated with all three species of extant bone‐collecting hyenids from four countries and two continents, six of the seven previously established criteria and reconsiderations of criteria have been evaluated. The results of the present study indicate that of the six criteria examined, none, as written, are indicative of hyenid activity on bone assemblages of unknown origin. Copyright © 2008 John Wiley & Sons, Ltd.     

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.     

Skeleton decay of <Emphasis Type="Italic">Cervus elaphus hispanicus</Emphasis> carcasses in Mediterranean ecosystems: biostratinomy at Sierra Norte of Seville natural park (SW Spain)

Taphonomic studies of faunal assemblages from archaeological and palaeontological sites need biostratinomy research to endorse their results. Many papers have studied the relationship between the differential conservation of anatomical parts and the animal responsible for the deposits. In this paper, we present the biostratinomy results from 18 Cervus elaphus hispanicus carcasses (Hilzheimer 1909) in a Mediterranean ecosystem (the Sierra Norte Mountains in Seville Natural Park). We also describe the skeleton decay related to scavenger community, where Sus scrofa (Linnaeus, 1758) is maybe the most important bone scavenger in our study area. These results of this research were compared to those obtained from a similar study carried out in Doñana National Park (Huelva) and confirmed that post-mortem tendencies are similar in both ecosystems.     

Polarizing Microscopy Identification of Chemical Diagenesis in Archaeological Cementum

Cementum increment analysis can potentially retrieve relatively complete, high-precision seasonality and mortality profiles from archaeological mammalian tooth assemblages. However, cementum exhibits many similarities to bone in composition, histology, ultrastructure, and even microstructure. Consequently, the mineralized dental tissue may be prone to the same processes of post-depositional chemical alteration that affect bone. This article reviews the issues surrounding chemical diagenesis in cementum and presents a new application to archaeological ungulate cementum of a polarizing microscopy technique that has previously been utilized to identify the effects of chemical diagenesis in archaeological bone and human cementum (Geusa et al., 1999; Gilbert, 1989; Watson, 1975; Zeder, 1978). It is argued that the post mortem leaching of collagen and the diagenetic growth of apatite crystallites can develop into banded features that mimic seasonal cementum increments. This pattern of diagenesis is demonstrated in multiple locations on a macroscopically well-preserved Upper Pleistocene-age archaeological tooth, which was previously interpreted by the author to exhibit biogenic seasonal cementum increments (Stutz, 1993; Stutz et al., 1995). It is suggested that if researchers seek to retrieve seasonality and mortality data from archaeological cementum, the microscopy analysis protocol must include screening of a pilot sample for the frequency and extent of chemical diagenesis.     

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.     

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.     

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.     

A taphonomic study of the African wild dog (Lycaon pictus)

Carnivore taphonomy has been traditionally used for the interpretation of archaeological sites in order to discriminate human-generated or modified from non-anthropic bone assemblages. In most of this actualistic research, the focus has mainly been placed on hyenas and felids, neglecting other carnivores. This paper analyzes the taphonomic impact of the African wild dog (Lycaon pictus) on equid bones and compares it with the bone modification patterns produced by other canids, such as wolves (Canis lupus) in order to compare medium-/large-sized canid variability on bone modification patterns and elaborate a referential framework which could be feasibly applied to the zooarchaeological record to detect canid intervention on archaeological assemblages in the past.     

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.     

A bone grease processing station at the Mitchell Prehistoric Indian Village: Archaeological evidence for the exploitation of bone fats

Recent excavations at the Mitchell Prehistoric Indian Village, an Initial Middle Missouri site in Mitchell, South Dakota have revealed a large, clay-lined feature filled with fractured and fragmented bison bones. Fracture and fragmentation analysis, along with taphonomic evidence, suggests that the bones preserved within the feature represent evidence of prehistoric bone marrow and bone grease exploitation. Further, the character of the feature suggests that it served as a bone grease processing station. Bone fat exploitation is an activity that is frequently cited as a causal explanation for the nature of many fractured and fragmented bone assemblages in prehistory, and zooarchaeological assemblages have frequently been studied as evidence of bone fat exploitation. The Mitchell example provides some of the first direct, in-situ archaeological evidence of a bone grease processing feature, and this interpretation is sustained by substantial analytical evidence suggesting bone fat exploitation. This new evidence provides a clearer concept of the nature of bone fat exploitation in prehistory as well as an indication of the scale and degree to which bone grease exploitation occurred at the Mitchell site. Finally, this research demonstrates the importance of careful zooarchaeological and taphonomic analysis for the interpretation of both artifactual remains as well as archaeological features.     

The Middle Pleistocene argali (Ovis ammon antiqua) assemblages at the Caune de l'Arago (Tautavel,Pyrénées‐Orientales,France): were prehistoric hunters or carnivores responsible for their accumulation?

The argali (Ovis ammon antiqua) assemblages from the Middle Pleistocene site of the Caune de l'Arago (Tautavel, southern France) were studied in terms of zooarchaeology and taphonomy. It is possible to discern palaeobiological information lost during fossilisation, as well as the palaeoethology of the bone collector, by the observation of taphonomic details preserved on the bone assemblages. The observations leave no doubt that both humans and carnivores were involved in the accumulation of argali carcasses in the cave. In some assemblages, the type of bones found in articulation and the gnawing marks observed are characteristic of carnivores. In other levels, the intense fracturing of the major limb bones in relation to their marrow content and mineral density, and butchering marks found on specimens in the earlier levels, are in favour of human accumulation, the modalities of which are discussed. The results suggest that the degree of carnivore activity seems to have been higher in levels M, N and O than in level F. Copyright © 2006 John Wiley & Sons, Ltd.     

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.     

The recovery and interpretation of microvertebrate bone assemblages from archaeological contexts

The analysis of microvertebrate remains recovered from buried contexts is frequently problematic for archaeologists. Diminutive size is a major obstacle to recovering, identifying, and interpreting microfaunal bone materials successfully. Their taphonomic history is often obscure, thus the significance of microvertebrate accumulations for settlement, subsistence, and ecological interpretation is difficult to evaluate. Recognizable and reliable archaeological signatures are sought for assessing the effect of taphonomic history on microvertebrate assemblages. Relevant signatures of bone damage, skeletal survivorship, taxonomic composition, and context are examined in assemblages produced and modified through accidental non-predator-related death, predator accumulation, and postmortem alteration.     

Process and terminology in mammal carcass reduction

A simple process-functional model is developed to explore some of the main stages in the utilization of a mammal carcass by people aiming to maximize the use of the carcass. The model predicts the potential deposition of many different and distinctive bone assemblages, some of which would be archaeologically recoverable. Explicit terminology is needed in order to distinguish assemblages of waste material from the intended product of a particular process, and to distinguish between assemblages characterized by depletion of certain elements and those in which parts of the carcass have been supplemented.     

Bone Diagenesis and Taphonomic History of the Paso Otero 1 Bone Bed, Pampas of Argentina

Samples of guanaco bone from an archaeological site in the Pampas of Argentina have been analysed to understand the diagenetic profile of the bone assemblages that characterized the taphonomic history of the site. Two archaeological occupations of Paso Otero 1 were investigated, encompassing similar landscape settings, climates, and depositional environments. The time span is a c. 2000 year period from c. 4800 to 2800 years . A total of 30 bone samples taken from both occupations were used to provide a preliminary characterization of the diagenetic pathways at the site. The parameters investigated provide a comprehensive account of how both mineral (hydroxyapatite) and bone protein (collagen) have been altered. In order to compare the two bone assemblages in terms of their diagenetic parameters, multivariate analyses were conducted. Results indicate two different diagenetic profiles in the site, % N being one of the variables that accounts for most of the variation in Paso Otero 1. The diagenetic analyses indicate that protein is less preserved in the bone assemblage from the middle stable landscape. Alternative interpretations of the diagenetic profiles are discussed in light of the taphonomic history of the site, and palaeoenvironmental information of the region. One hypothesis stresses the importance of the role of climate in defining the different diagenetic pathways, and the other the continued action of the combined diagenetic factors along time as the main explanation for the variability in the state of preservation of the bones in Paso Otero 1.     

Small prey hunting technology and zooarchaeological measures of taxonomic diversity and abundance: Ethnoarchaeological evidence from Central African forest foragers

Archaeological analyses of faunal assemblages often rely on rationale derived from the prey choice model to explain temporal and spatial changes in taxonomic measures of diversity and/or abundances. In this paper, we present analyses of ethnoarchaeological observations and bone assemblages created by Central African Bofi and Aka forest foragers which show that different small prey hunting technologies target specific suites of prey and that hunters vary their technological choice depending on their foraging goals. Analysis of ethnoarchaeological bone assemblages produced by the Bofi and Aka shows that variability in target prey can create spatially distinct, but contemporaneous, faunal assemblages with different diversity values and abundance indices. These data reveal important variation in how individuals within a contemporary human population rank prey and challenge current assumptions about the meaning of diversity and abundances measures in archaeological contexts. We argue that the use of diversity and abundance indices can obscure important intrasite variability in prehistoric foraging effort and suggest strategies that might enhance current techniques.