Preparing Your Assemblage

1. Organize bags of animal bone by provenience.

2. Use an inventory of these bags and their provenience as a checklist.

3. Inspect the bones contained in several bags before beginning your analysis.

4. Use one or more metal or plastic trays to hold the bones of a single bag while analyzing them. Be sure to keep the provenience information with the bones by placing labels on or in each tray.

5. Use a denture brush and dull-tipped dental picks to remove dirt as needed.

6. Use a 10X magnification loop to inspect the bone as needed.

7. Sort bones from a single bag by laying them out with the most similar ones together.

8. Remove any non-bone materials such as rocks, twigs, and fragments of ceramic; bag these separately as “non-bone”; be sure to preserve the provenience information.

9. Set up a sandbox for bone mending.

10. Inspect the bones for fresh breaks and make any mends that are possible.

Sorting Bone from Non-Bone

Bone vs. Stone—Bone sticks to the tongue. Stone produces a sharp sound when dropped on a table.

Bone vs. Ceramic—Bone sticks to the tongue. A thumbnail can scratch calcined bone. Most ceramics will not stick to the tongue or be easily scratched.

Bone vs. Plant—Bone usually does not float. Plant material will compress if pushed on with a thumbnail.

Making Identifications with Certainty

1. Reliable data is what you know, not what you think. Always check your intuition against a reliable source. No matter how many deer femurs you have seen in your lifetime, you should always compare the bone you think is a deer femur to an actual deer femur, or a scale illustration of a one. Don’t get sloppy just to save time.

2. Exclusion is as important as inclusion. Sometimes figuring out what your bone is not is the simplest way to increase your certainty as to what it actually is. Check species lists for the other sites in the area. Check the geographic distributions of species in the state.

3. If you are going to make an unusual identification, you need to be 100 percent certain. Don’t identify an Arizona gray squirrel tibia in an assemblage from New York unless you are positive it is an Arizona gray squirrel and not an eastern gray squirrel.

4. Ignore identifications made by others. Field bags and field notes are filled with the intuitions of others, and often these notes can lead you astray. I once spent days looking for a sheep skull that a field crew kept asking about only to discover that the pig cranium I had already identified had been mistakenly identified by the crew.

5. Don’t make an identification just to avoid admitting you are not sure what it is. Every assemblage has its unidentifiables.

Identifying Antler and Horn Fragments

Antler—very wood-like or bark-like exterior surface and very dense outer cortex and inner spongy bone, no interior cavity

Horn—very dense exterior and interior surfaces are porous with holes penetrating from the exterior surface into the interior

Characteristics of Vertebrae by Taxonomic Class

Mammal—large size with complex shape, large central foramen, flat articular surfaces

Fish—roundish solid centrum with little or no central foramen

Bird—complex shape with small central foramen, saddle-shaped articulations, rear-facing spines on lateral surfaces, fusion of vertebrae

Reptile—small central foramen, roundish central body with a ball-like projection at one end and a depressed articular surface at the other (turtles have two lobes on central body)

Amphibian—small central foramen, oval-ish central body with relatively flat articular surfaces, large lateral projections

Differentiating Mammal Vertebrae

Cervical—small centrum; overall ring-like shape; three foramina

Thoracic—larger centrum; large spinous process

Lumbar—largest centrum; short spinous process; large transverse processes

Sacral—fuse to form sacrum

Caudal—small central foramen or no foramen; small transverse processes; may appear star-shaped in cross-section

Differentiating Fish Vertebrae

Cervical—no neural spine

Thoracic—neural spine extends up from central body and points toward tail

Precaudal—neural spine plus transverse processes extending out to sides

Caudal—neural spine plus haemal spine extending downward

Penultimate—only a short neural spine

Ultimate—no spines, support for tail fin present

Differentiating Bird Vertebrae

Cervical—small centrum; three foramina; rear-facing thin bone projections (hypapophyses)

Thoracic—larger centrum; large neural arch and spinous process; may be fused together

Lumbar—fused vertebrae; also fused to sacral vertebrae and pelvis

Sacral—fused to pelvis as part of synsacrum

Caudal—small centrum with spinous and transverse processes

Pygostyle—vertebral body with finlike projection

Identifying Fragments of Vertebra

Mammal—tend to break into complex shapes; fragments of centrum are porous; fragments of spinous and transverse processes resemble ribs but are thinner

Fish—tend to separate into round central bodies and long, thin spines; the bodies resemble spools with depressed ends; the spines resemble sewing needles with a triangular end at the attachment to the centrum

Bird—vertebra are robust and often fused together or to other bones, making breakage difficult

Reptiles—vertebra are small and robust, making breakage difficult

Amphibians—vertebra are small and robust, making breakage difficult

Identifying Rib Fragments

Mammal—squarish in cross-section; inner spongy bone is more organized and less dense than in long bones

Fish—very long, thin, and curved with transparent to translucent character

Bird—flat and some are forked near mid-shaft for the uncinate process

Identifying Fragments of Pelvic Girdle

Mammal—complex shape with thin to thick outer cortex and disorganized spongy bone throughout the interior

Bird—fragments that do break off tend to be very thin; otherwise the fusion makes the bone resistant to breakage

Reptile—density of the acetabulum and ilium makes these the most common fragments that are still identifiable

Amphibian—density of the acetabulum and ilium makes these the most common fragments that are still identifiable

Characteristics of Pelves by Taxonomic Class

Mammal—deep acetabulum and large obturator foramen

Fish—located near cranium; has fin support structures; shaped like a wishbone

Bird—fused together to form synsacrum; three foramina form diagnostic pattern

Reptile—very shallow acetabulum, except those with large obturator foramina; turtle and tortoise pelves resemble a party mask

Amphibian—ilium tends to be the most prominent component of the pelvis

Identifying Fragments of Shoulder Girdles

Mammal—large fragments of thin and flat bone, with no clear interior surface, are usually fragments of mammal scapulae

Fish—resemble cranial fragments

Bird—scapula fragments resemble rib fragments without uncinate process; coracoids break below proximal articulation, leaving blade fragments that are relatively flat but often with shallow depressions or raised lines

Reptile and Amphibian—small size and density makes them resistant to breakage

Characteristics of Shoulder Girdles by Taxonomic Class

Mammal—triangular-shaped scapulae; no coracoids

Fish—no scapulae; do have coracoids and clavicles as a complex of fused bones just behind the cranium

Bird—scapulae are rib-like in appearance; coracoids are hooked at one end; clavicles are fused to form furcula

Reptile—shoulder girdle resembles pelvic girdle but with longer and thinner elements

Amphibian—shoulder girdle resembles pelvic girdle but with longer and thinner elements

Identifying Upper Limb Elements

Humerus—proximal articulation is convex (rounded) to form shoulder

Ulna and Radio-ulna—proximal articulation is concave (cupped) to form elbow

Radius—proximal articulation is relatively flat in profile but relatively circular in plan

Identifying Upper Limb Fragments of Mammals

Humerus—shaft is a twisted cylinder; proximal end is a round knob; distal end is complex with the shaft dividing into two parts just before the articulation

Ulna—proximal end is a hook; shaft is relatively thin but is almost entirely hard cortex; distal end tapers to a point

Radius—proximal end is flat with a slight depression and round to oval in shape; shaft is often D-shaped in cross-section; distal end flares out

Identifying Upper Limb Fragments of Birds

Humerus—proximal articulation is rounded and contains a diagnostic fossa and/or crest; distal articulation resembles a clenched fist

Ulna—shaft is relatively round in cross-section; may have a column of raised quill knobs along shaft; proximal articulation is sloped; distal articulation is W-shaped

Radius—shaft is relatively round in cross-section; proximal articulation is roundish with a small facet just below it

Carpometacarpus—very dense and complex-shaped bone; proximal articulation resembles a pulley; shaft is split in two; distal articulation may have stepped appearance

Identifying Upper Limb Fragments of Reptiles

All are relatively paddle-shaped with a dense outer cortex. Articular ends are relatively shapeless when compared to those of mammals.

Identifying Upper Limb Fragments of Amphibians

Humerus—proximal shaft has a crest but otherwise has a tubelike appearance and some curvature; distal end is rounded and ball-shaped

Radio-ulna—proximal end is concave, and shaft is clearly two shafts fused together; distal end is tubelike but two tubes fused together

Characteristics of Upper Limbs by Taxonomic Class

Mammal—proximal humerus has a rounded knob; proximal ulna has a hook; radius is D-shaped in cross-section

Bird—proximal humerus is rounded; distal humerus resembles a clenched fist; radius and ulna are both long and thin; carpometacarpus has a pulley on proximal end and a stepped distal end

Reptile—humerus, radius, and ulna are all globular and somewhat paddle-shaped

Amphibian—humerus has a rounded distal articulation; radio-ulna is concave at the proximal articulation and fans out from there with two shafts fused together

Identifying Lower Limb Fragments of Mammals

Femur—shaft is very round in cross-section; proximal end has projections known as trochanters; distal end has two large, rounded condyles

Tibia—proximal shaft is triangular in cross-section; distal shaft is D-shaped in cross-section; proximal end has two articular surfaces separated by a small ridge; distal articular end has a projection that is positioned medially

Fibula—shaft is long and relatively thin and sometimes is fused to the lateral shaft of the tibia

Identifying Lower Limb Fragments of Birds

Femur—resembles mammal femur but has much thinner walls and is lighter in weight

Tibiotarsus—proximal articulation is very angular; distal shaft has a shallow canal running down it; distal articulation resembles that of a femur but with less-prominent condyles

Tarsometatarsus—distal end has three-pronged shape or three trochleas; proximal articulation resembles that of a mammal tibia but has two foramina, one on the medial and one lateral side of the anterior shaft surface

Identifying Lower Limb Fragments of Reptiles

All are relatively paddle-shaped with a dense outer cortex. Articular ends are relatively shapeless when compared to mammals.

Identifying Lower Limb Fragments of Amphibians

Femur—long and thin with no clear features

Tibiofibula—resembles a long, thin, and compact X shape with a depression or foramen at the center

Characteristics of Lower Limbs by Taxonomic Class

Mammal—femur has two large projections at each end; tibia is triangular at proximal end and D-shaped at distal end

Bird—femur resembles that of a mammal but with less distinctive shape; distal end of tibiotarsus can be mistaken for a femur, but the proximal end is very tibia-like; tarsometatarsus has complex three-pronged shape to distal articulation

Reptile—femur, tibia, and fibula are all somewhat paddle-shaped

Amphibian—femur and tibiofibula are long and thin with few features

Identifying Metacarpal and Metatarsal Fragments of Ungulates

Both have a very dense outer cortex with little interior spongy bone. Interior may show remnants of the fusion of two bones together; this is also sometimes evident on the exterior of the bone.Metacarpals—proximal articulation is D-shapedMetatarsals—proximal articulation is square

Characteristics of Mammal Metapodials

Carpals—often resemble small rocks, but have many smooth articular surfaces in between rough surfaces; usually smaller than tarsals

Tarsals—larger size and more complex shape makes them easier to identify than carpals

Metacarpals and Metatarsals—distal end has knob shape or pulley shape

Phalanges—proximal end is concave; distal end is convex; a small shaft is in between

Body Size Classes


Tiny—finch or sparrow (<50 grams or 1.76 ounces)

Small—thrush (50–100 g or 1.76-3.53 oz)

Medium—pigeon (100–400 g or 3.53-14.11 oz)

Large—chicken (400-3000 g or 14.11-105.82 oz)

Very large—goose (>3 kilograms or 6.6 pounds)


Size 1 or Small Mammal—rabbit (< 50 pounds or 22.68 kilograms)

Size 2 or Medium Mammal—pig (50–250 lbs or 22.68-113.40 kg)

Size 3 or Medium-Large Mammal—deer (250–750 lbs or 113.40-340.19 kg)

Size 4 or Large Mammal—cow (750–2000 lbs or 340.19-907.18 kg)

Size 5 or Very Large Mammal—elephant (> 2000 lbs or 907.18 kg)

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