Offering a field-tested analytic method for identifying faunal remains, along with helpful references, images, and examples of the most commonly encountered North American species, Identifying and Interpreting Animal Bones: A Manual provides an important new reference for students, avocational archaeologists, and even naturalists and wildlife enthusiasts. Using the basic principles outlined here, the bones of any vertebrate animal, including humans, can be identified and their relevance to common research questions can be better understood. Because the interpretation of archaeological sites depends heavily on the analysis of surrounding materials—soils, artifacts, and floral and faunal remains—it is important that non-human remains be correctly distinguished from human bones, that distinctions between domesticated and wild or feral animals be made correctly, and that evidence of the reasons for faunal remains in the site be recognized. But the ability to identify and analyze animal bones is a skill that is not easy to learn from a traditional textbook. In Identifying and Interpreting Animal Bones, veteran archaeologist and educator April Beisaw guides readers through the stages of identification and analysis with sample images and data, also illustrating how specialists make analytical decisions that allow for the identification of the smallest fragments of bone. Extensive additional illustrative material, from the author’s own collected assemblages and from those in the Archaeological Analytical Research Facility at Binghamton University in New York, are also available in the book’s online supplement. There, readers can view and interact with images to further understanding of the principles explained in the text.
About the Author
APRIL M. BEISAW is an assistant professor of anthropology at Vassar College in Poughkeepsie, New York, and an adjunct research associate in anthropology at Binghamton University. She has served as an independent faunal analyst since 1998 and has analyzed assemblages from prehistoric and historic sites across North America.
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Identifying and Interpreting Animal Bones
By April M. Beisaw
Texas A&M University PressCopyright © 2013 April M. Beisaw
All rights reserved.
The ability to identify animal bones from archaeological sites is a skill that few archaeologists develop without dedicated instruction in a classroom environment. In the absence of such a course, it is difficult to learn animal bone analysis, also known as faunal analysis or zooarchaeology. Most books on the topic can be either daunting in their coverage of the vast literature on method and theory or overly simplistic in their illustrations of complete bones of specific animals with little instruction on how to use them. What is missing are books that guide readers through the processes of comparing archaeological bones and bone fragments to known specimens or illustrations This book models the steps that an experienced analyst might follow, from receiving specimens to writing a basic report.
This manual should be used in conjunction with real animal skeletons, known as comparative collections, and books that illustrate the complete bones of specific species, known as bone atlases. For guidance on analyzing and interpreting the resulting data, books on zooarchaeological method and theory (e.g., Reitz and Wing 2008) should be consulted. Faunal analysis requires numerous resources, and the text identifies some "tools of the trade." A more detailed directory of resources is also available in the online appendix (see appendix 1).
Although readers can use this manual to identify a single bone fragment from any context, it is written specifically for those who wish to identify a large quantity of animal bone from an archaeological site. A collection of objects from an archaeological site is known as an assemblage. This term is not specific to animal bones. For example, the collection of stone tools from an archaeological site may be referred to as a lithic assemblage. It is common practice for animal bone to be separated from all other artifacts and for the bone assemblage to be provided to a single person, the faunal analyst, for identification and analysis.
Chapter 2, Preparing Your Assemblage, outlines the organizational steps to follow when an animal bone assemblage is received. Bones should be cleaned before they are sent to an analyst, but some additional cleaning is usually required. An initial sorting step reduces an intimidating pile of generic bone into smaller and more manageable piles of bones that share similar characteristics. This allows variability in the assemblage to become more obvious. Faunal analysis is all about pattern recognition. The first pattern an analyst should recognize is that of freshly broken bone, which may be mended to increase the identifiability of the assemblage as a whole.
Identification then proceeds in one of two directions: either toward the type of animal the bone came from first and then what bone it is or toward the type of bone first and then what animal it came from. In reality both processes are used simultaneously as analysts refine their identification. For example, a bone fragment may first be identified as a mammal bone, then a fragment of mammal femur, then as a white-tailed deer femur. To simplify this manual, instruction for identifying the type of animal is provided before that for identifying the type of bone simply because the former require fewer decisions. However, these chapters have been written so that they can be used in either order, depending on the analyst's needs.
Chapter 3, What Animal Is It?, provides keys for identifying the patterns that distinguish one animal skeleton from another. A basic knowledge of taxonomy, the organization of all living things based on similarities in their bodies and their behavior, is needed. The first question an analyst asks is, what taxonomic class (e.g., Mammalia, or mammal) of animal is this? This question can be answered by evaluating the texture, curvature, and thickness of the bone. The more specific the identification gets, the more knowledge is required. To discern what taxonomic order (e.g., Carnivora, or carnivore) or family (e.g., Canidae, or dogs and their relatives) the animal belongs to, an analyst must be able to recognize the patterns of functional morphology; the shape of an animal's bones are the result of how its bones function. For example, mammals that run fast often have fewer foot bones than mammals that do not; multiple foot bones that have fused make a more efficient runner. Functional morphology may or may not help an analyst discern the genus or species that a bone represents (e.g., Canis lupus). To arrive at this level of specificity, the analyst needs an understanding of the species available to site inhabitants. Once a list of suspects has been compiled, comparative illustrations or specimens are used. If common species can be ruled out, more exotic species are considered. If a specimen cannot be identified below the level of taxonomic class, it is described using an estimated size of the animal within its class (e.g., medium mammal).
Chapter 4, What Bone Is It?, provides keys for recognizing patterns that distinguish one skeletal element (e.g., humerus or radius) from another. The easiest elements to identify are dealt with first, those of the head and those of the chest and abdomen (thorax). While fragments of these bones are readily apparent to a trained analyst, they are not easily identified to a particular genus or species. Teeth are the most identifiable element in the body, and in many cases a single tooth can be identified to the species level. Most animal bone assemblages are primarily composed of limb fragments. Techniques for discerning one type from another are described. For example, a fragment of mammal long bone that is triangular or D shaped in cross-section is almost always from a tibia or radius. After the bone is identified to a specific animal and element, the side of the body from which it comes can be determined. In some cases the sex and age of the animal can also be established.
Chapter 5, What Else Can the Bone Tell Me?, provides an overview of the taphonomic information that many bones contain. Taphonomy is the study of everything that happened to an animal from the time it died until it is described in a technical report. Some taphonomic processes leave marks on bones that can be identified and interpreted. Examples include bone broken for the extraction of marrow, cut for the removal of flesh, burned as part of cooking or trash disposal, weathered from long-term exposure to the elements, gnawed on by carnivores or rodents, or shaped by humans into tools or ornaments. Some taphonomic processes destroy bones before they can be recovered through archaeology. To gauge the amount of bone destruction that has occurred, analysts can consider the density of the recovered bones and bone fragments. This allows for an estimation of how much destruction may have occurred and can help to answer questions such as "Did people at this site not eat fish?" or "Were all the fish bones destroyed by processes of trampling or animal gnawing?" For additional information on taphonomy, consult the volume Vertebrate Taphonomy by Lyman (1994).
Chapter 6, Recording Your Data, provides guidance on deciding what data to record and how to record it. Before databases became user friendly, analysts used tables of abbreviations to code their data. Databases no longer require codes, so it is largely up to the analysts to develop their own recording system.
Any two analysts can analyze the same assemblage and produce somewhat different data sets. Because animal taxonomy is hierarchical, a novice analyst can produce a database that is as accurate as one created by an expert yet not as precise. For example, a novice may identify a squirrel bone as a Rodentia (order) or a Sciuridae (family). Experience and an appropriate comparative collection may allow an expert to identify it as Sciurus carolinensis (genus and species). The novice's data are not wrong; they are just not as precise as the expert's. A more general identification is always preferable to guesswork. The same holds true for skeletal element identifications. A novice may refer to a fragment as long bone, whereas an expert may identify it as a left femur. Additional data recorded should include descriptions of the completeness of each element and which, if any, articulations (joints) are present. Bones should always be counted, but they may also be weighed as long as they are clean. The presence of taphonomic marks (e.g., cut marks) should be noted, and any additional information may be added to a "comments" field.
PRECISION VS. ACCURACY
A precise identification is very specific but may not be correct. Species-level identification is very precise, whereas genus-level identification is less precise. Precision is useful only when the identification is accurate.
An accurate identification is correct, but it may not be very specific. A genus-level identification may be less precise, but if there is any question as to which species is represented, it may be the most accurate identification possible.
Chapter 7, Presenting Your Data, covers the basic calculations that all faunal analysts should perform on their assemblages: number of identified specimens (NISP) and minimum number of individuals (MNI). These calculations can be applied at multiple scales to allow for comparisons between different areas of the same site or for comparison between sites. While other faunal analysts will be most interested in your NISP and MNI numbers, nonspecialists will benefit from other ways of summarizing the assemblage composition. Body-part profiles are one such technique. These drawings illustrate which bones of a specific type of animal were identified. For other ways to quantify and present your data, consult Zooarchaeology by Reitz and Wing (2008) and Quantitative Paleozoology by Lyman (2008).
Some general advice on preparing a faunal report is provided along with examples from actual archaeological sites. There is little standardization in animal bone analysis, and just one approach is presented here. Additional examples can be found in the online appendix (see appendix 1), which also contains photographic versions of all the bone images that appear here as line art (drawings) as well as some additional content.
This book is a manual and as such is not intended for a cover-to-cover read. Instead, select the chapter or section within a chapter that fits your needs at any given time during your analysis. If you need help deciding whether a bone fragment is that of a fish, skip to chapter 3. If you think you have a bone from a bird's wing, jump to the "Upper Limbs" section of chapter 4. If you are not sure what bone you have, browse through the figures until you see one that resembles it, and read the adjacent text for clues on how to identify that type of bone.
Animal bone analysis requires memorization of taxonomy and skeletal anatomy. Two features of this manual are designed to help with the tedious task of memorization. First, terms that every faunal analyst should know are defined in the text, and these definitions are also compiled into a glossary. The first instance of each term appears in "light" boldface type. Second, common and technical forms of taxonomic and anatomical terms are usually shown together throughout the manuscript to minimize the need to refer to the glossary while reading. To the expert, this may seem redundant. To the novice, it is likely a welcome teaching tool.
This manual does not contain bone illustrations in which each bone or bone feature is labeled with a corresponding technical name. Such figures are widely available in other books. Instead, the figures here allow the reader to examine the shapes of bones without distracting labels and to read corresponding textual descriptions of these shapes to enhance the three-dimensional visualization necessary for bone identification.
This brings us to some standards of taxonomy. The genus and species names of animals used in this book are provided in parentheses after the common name for that animal. Additionally, both genus and species names are italicized, and the genus name is capitalized whereas the species name is not. These are standards that you should adhere to. When reviewing lists of animals identified from other assemblages, you may see something like (Gallus sp.) or (cf. Gallus gallus). These are shorthand for tentative identifications. The former (sp.) means the specimen was identified to the genus Gallus but the species could not be discerned. The latter (cf.) means the specimen compares well with Gallus gallus but is not a perfect match. Some sources use sp. to represent "species" in the singular form and spp. to represent "species" in the plural. Therefore, if your specimen may be one of multiple species of Gallus, the correct identification would be Gallus spp. rather than Gallus sp.; however, this distinction is not uniformly applied in faunal analysis.
GENUS AND SPECIES NAMES
Genus names are always capitalized.
Species names are never capitalized.
Genus and species names are always italicized.
When one genus name is used repeatedly, it is acceptable to abbreviate the genus using just its first letter in italics followed by a period (e.g., Canis sp. as C. sp.). To do so, the genus being abbreviated must be obvious from the context within which the abbreviation is used. For example, if you have written a paragraph about the species of the genus Canis and then a paragraph about those of the genus Cervus, any use of C. in a third paragraph would imply the genus Cervus. Because of the potential for confusion, use of the genus abbreviation should be minimal.
COMMON TAXONOMIC SHORTHAND
sp.—an unspecified species
spp.—multiple unspecified species
cf.—compares well with but is not a perfect match C. (or any italicized capital letter followed by a period)—abbreviation for the genus; use only if the same genus name was recently used. For example, a set of Canis species can be written out as Canis lupus, C. rufus, C. latrans.
Before identifying your bone specimen to a specific genus or species, it is necessary to determine what bone or skeletal element the specimen represents. The chapters that follow provide instruction on how to identify both complete and fragmentary remains. Domestic species contain a significant amount of skeletal variation. This is due to selective breeding and the creation of distinct breeds. There are more than eight hundred breeds of domestic cow and hundreds of breeds of domestic chicken (Gallus gallus). While your favorite bird bone atlas may illustrate the skeletal elements of the domestic Gallus gallus, the chances that your bone will perfectly match any chicken bone are small unless the breed of your bone specimen happens to match the breed of the illustrated bone. The same is not true for wild species. The bones of wild species often form near-perfect matches with atlas illustrations of wild species.CHAPTER 2
Preparing Your Assemblage
Although it is common for colleagues, friends, and strangers to thrust a bone at an analyst for on-the-spot identification and interpretation, faunal analysis is more nuanced than this. Of course, even an inexperienced analyst can provide general information about almost any presented specimen, but an accurate and precise identification usually requires a bit of lab work. Until you have a couple of years of analysis under your belt, avoid the temptation to perform such party tricks.
Bones should be provided to a faunal analyst only after they have undergone preliminary cleaning and quantification in the laboratory. At a minimum, bone should be dry-brushed to remove surface dirt and then bagged by provenience, the location from which the bone was recovered. Bone should not be presorted by field or lab technicians because incorrect identifications by nonspecialists create many logistical problems in record keeping and hinder the faunal analyst's ability to recognize patterns in the collection. A paper inventory of the bagged bone that includes provenience and bone count should accompany the faunal assemblage when it is transferred to the analyst. This inventory can serve as an ordered checklist to guide analysis. It also provides the analyst with reliable typewritten provenience information, which is often easier to read than the handwritten tags that accompany artifact bags.
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Table of Contents
1 Introduction 1
2 Preparing Your Assemblage 7
Cleaning Bones 8
Sorting Bones 10
Mending Fresh Breaks 12
3 What Animal Is It? 17
Class: Mammal, Fish, Bird, Amphibian, or Reptile? 18
Order and Family: A Question of Functional Morphology 24
Mammal Orders 28
Fish Orders 33
Bird Orders 35
Amphibian Orders 37
Reptile Orders 37
Genus and Species: Environment and Economy 40
4 What Bone Is It? 47
Skulls and Teeth 54
Vertebrae and Ribs 59
Pelvic and Shoulder Girdles 70
Pelvic Girdle 71
Shoulder Girdle 75
Upper Limbs 79
Lower Limbs 88
Hands and Feet (Manus and Pes) 94
Siding Bone 98
Determining Sex and Age 99
5 What Else Can the Bone Tell Me? 103
Broken Bone 104
Cut Bone 105
Worked Bone 108
Burned Bone 109
Weathered Bone 111
Gnawed Bone 112
Digestive Damage 113
The Biased Assemblage 113
6 Recording Your Data 117
Levels of Certainty 117
Size Classes 120
Mutually Exclusive Categories 120
Completeness and Articulations 123
Counting and Weighing Bone 123
Your Research Questions 125
Comment Fields 126
7 Describing Your Data 129
Common Calculations 129
Body-Part Profiles 133
Contextual Analysis 136
Producing a Faunal Report 136
Appendix 1 Online Appendix 143
Appendix 2 Bone Atlases 144
Appendix 3 Mammals, Fish, Birds, Reptiles, and Amphibians by Habitat Preference 146