WEEK 4-taphonomic studies of human remains Flashcards
Taphonomic
study of how organisms decay and become fossilized
Biosphere to lithosphere
Taphonic processes- the biological and physical changes that occur
- post mortem= before burial
- post burial= before excavation
- Post excavation= before study
What does taphonomy help the investigator determine?
The depositional history of a given set of skeletal remains
identify agents of modification and destruction
cultural activates as opposed to natural changes- human intervention?
biases of human composition
Agents, processes and factors?
- Agents- source which causes the modification eg. human, animal
- process- action performed by the agent that causes the modification eg. scavenging butchery
- factor- chemical, physical, biological, cultural
Why was it originally developed?
for palaeontology to explain how and why extent animals become fossilised and preserved in the geological record
taphonomy impetus from research advances in forensic anthropholgy
Understanding the post mortem history of human skeletal remains, trauma analysis, violence vs excavation damage
How can you tell whether remains are human or animal?
Surface of animal bones are more polished and bones are more denser
How can you tell if bones are modern or archaeological?
Modern bones has organic collagen component present, it is heavier and denser and has a more greasy feel
archaeological= more rougher
Assessing the condition of the bones
- Completeness- % of skeleton present
- fragmentation-post mortem breakage
- preservation- condition of the cortical surfaces (erosion, burning, weathering)
Scavenging affect on bones
canviores disarticulate animal carcasses in a regular sequence
early - femur from hip, mandible from cranium, atlas from cranium, humerus from scapula, caudal vertebrae, distal phalanges
middle- femur to hip bone, tibia from femur, tarsals, metatarsals, ribs, humerus from radius, carpals, metacarpals etc
late- sacrum from hip, cervical thoracic and lumbar vertebrae
Fragmentation- incidental
- Disturbance in burial
- breakage during excavation- depending on condition of soil, breaking bones,
- trampling
- peri-mortem fracturing
Intentional fragmentation
- Peri mortem fracturing- can result from interpersonal violence
- butchery- animal
- amputation/ disemberment
Bone surface modification- like amputation with saw
sharp edges would suggest patient did not survive
could also be intentional disposal of human body parts
Intrinsic preservation factors of bone degradation
size- larger bones more likely to survive
porosity
amount of compact or cancellous bone- high amounts of cancellous vs compact
extrinsic Factors for preserving bone degradation
Soil PH- more acidic causes pitting of bone together and thinning of cortical bone margins
Presence of H20 and O2
temp
microbial organisms- action of bacteria is driving decay
duration of burial
Recording surface preservation (brickley et al 2004)
0) absence of modification of surface
3) most surface affected with some details obscured
5) heavy erosion of surface and modifying profile
* increase degradation down scale
Fluvial transport and dispersal
Action of water on bone, influence of water currents on preservation
fluvial dispersal on bones depends on bone shape and density
Fluvial dispersal bone groups
1- light bones that tend to float and are easily moved: ribs, vertebrae, sacrum, sternum
2- intermediate bones that sink and are intermittently lomved- long bones, scapula, pelvis, metapodials, phalanges
3- dense bones that sink and are relatively immobile, forming a lag deposit : mandible, animal skull, deer antler
How can you tell if there is carnivore and rodent gnawing?
Puncture marks and removal of epiphyses (human bone)- tend to be around the long bones
Chiselling pattern
*rodents gnaw to wear down their teeth
