ANT 256 Lecture 10

Forensic Taphonomy

What is taphonomy and why is it an important element in analysis of human remains?

- Forensic Taphonomy
- postmortem (PM) changes to bone
- what happened to body between the time of death and the time of discovery (why its important)

Why study taphonomy?

- position, color, weathering, erosion
- consistent with
--> where and how body is found
--> tip or testimony
* what was done to body
- movement of body
--> animal, human, gravity, H2O
- elapsed time since death
- evidence
--> altered, added to, lost

Traditional Archaeological Taphonomy

- disarticulation sequences
--> loss of tissue
- animal scavenging
- animal scatter
- environmental transport
- weathering/discoloration
- survivability of skeletal remains

How do we identify scavenging marks? How do we tell the difference between different kinds of scavenging species?

different animals have different indicators to the type of scavengers
- animal activity
--> gnawing, digging, clawing

Carnivore scavenging/activity indicators

- punctures, channeling, marrow coning
- chew condyles, hands, epiphyses
- scalloped edges

Rodent scavenging/activity indicators

- gnaw on sharp edges
--> orbits, broken edges
- parallel chisel-like marks
- camouflage wounds
- nests in bodies

Other scavenger activity indicators

- sheep and deer
--> crunch shafts
--> double prong fragment
- pigs
--> crush bone
- porcupines
--> may carry up trees
- birds
--> peck holes
- bears
--> crush long bones
--> longitudinal cracks
--> few fragments
--> axial skeleton consumed

Disarticulation Sequences

- least stable --> most stable joints
--> joint type, amount and type of tissue
--> ball and socket (hip)
--> hinge (knee)
- normal decomposition
--> bacterial and enzymatic action

Typical Sequence (disarticulation)

- skull and atlas separate from vertebrae
- ribs loosen, chest collapses as the sternum disarticulates
- limbs disarticulate
- mandible from skull
- overlapping these stages
--> vertebral column disarticulates
--> weathering begins before vertebrae

Variation in Sequence (disarticulation): Insect Activity

may speed up process

Variation in Sequence (disarticulation): sedimentation and burial

fix position

Variation in Sequence (disarticulation): Water

head first, hands/feet, upper limb, leaving only a torso

Variation in Sequence (disarticulation): Other

- animal scavenging
- human intervention

Movement in Water

- moving water
--> round elements often transported further from the insertion site than flat or long bone
--> smooth, rounded in in water
--> eroded if water passes over/through

Movement on Land

- scratched, damaged
--> breaks more ragged -- not stained, no tissue adhering to "new" breaks

Exposure to Water

- Salt Water
--> adipocere
--> chalky, brittle, algae stained, barnacles, barnacle cement
- Fresh Water
--> adipocere
--> greasy, bone flaking

What are the different taphonomic forces and how do they affect bone?

- exposure to water
- erosion
- weathering
- color
- cuts, chops, saw marks, etc.

Taphonomic Forces: Erosion

- exposure to surroundings
- chemical erosion
--> acids and bleaches
- soil erosion -- often very irregular margins
- root etching
- mechanical erosion

Taphonomic Forces: Weathering

- exposure to elements
--> wind, rain, sun, etc
- sun bleaching, bone checking or cracking -- eventually leads to flaking and splintering
- rate -- environment
- no weathering 0-1yr
- falling apart, easily broken 6-15yrs or more

Taphonomic Forces: Color

- fresh -- yellow (grease)
- heat -- brown/black/blue-gray/white
- staining -- metal
--> green -- copper
--> iron -- orange
- bacteria/plants/soil
--> variety of colors
- lichen/moss
--> dark green
- sunlight -- white
--> greasy, dry, brittle

Taphonomic Forces: Cuts, Chops, Saw Marks, etc.

- AM alterations relate to process of death
--> trauma
- PM alterations
--> disposal of body
--> taphonomy -- it tells us the events that occurred after death

Antemortem Injuries

- evidence of bone healing/remodeling
- indicates that the individual survived the trauma
- rarely give clues to the manner of cause of death. But, they can be helpful in establishing identity if the victim had medical records. So we might cross check any records for individuals who match the biological description.

Perimortem Damage/Injuries

- pathology
--> contributing to cause of death
- anthropology
--> at of around the time of death
- bone behaves as if fresh
--> several weeks after death
--> submersion, freezing delay loss of collagen
- fire, heat accelerate loss of collagen

Postmortem Damage

- color differences
--> bone surface and cut or edge of break
* if damage is recent
- brittle tissue
- unnaturally squared angular edges

Why find the point of origin (dumpsite)?

- additional evidence and bones
- determined how remains were moved (an evidence of scavenging or body drag marks)
--> locate dumpsite

What are the indicators of a body dumpsite?

- scalp hair
- staining
- insect activity
- clothing