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Taphonomy & Decomposition
…a totally gross lecture topic
The study of the changes that occur to a body
after death, and its eventual destruction by
elemental and biological processes.
Goals of Taphonomy
• Reconstruct the environment of the
site
• Determine which factors cause the
destruction of the body
• Understand the transport of remains
• Discriminate human from nonhuman
agents of the body’s modification
Taphonomy
• Studies of Taphonomy are interested in:
– decomposition rates and patterns
– disarticulation
– dispersion of body parts
– modification of soft tissue and bone
• In order to show
– time and circumstances of death
– postmortem vs. antemortem/perimortem
conditions
– identifying factors – who was it?
Mortem – Time of Death
• Postmortem – after-death
• Antemortem – before death
• Perimortem – around the time of death
Two Factors of Taphonomic Change
• Autochthonous Changes
– happen where death occurred
• Allochtonous Changes
– happen at a place different from
where death occurred
A Forensic Taphonomic Model
• Four Dimensions of Post-Mortem Change
– objects
• human remains
– space
• on the surface
• within other environments (e.g. water)
• buried
• allocthonous vs. autochthonous effects
– modification of objects
– cultural dimension
• cause and manner
• investigator bias
Two Major Temporal Concerns
• Perimortem Interval
• includes the timing of specific
events such as trauma that occur
around the time of death
• Postmortem Interval
• Includes events that occur well after
the time of death
Perimortem Interval
• Estimating time of injury is difficult in the
best cases
• Must be able to determine conditions
under which taphonomic conditions come
into play
– but these processes are not precise, so
the boundary between life and death
becomes blurred
Postmortem Interval
• Also imprecise
• Right after death, the muscles of the body
become flaccid
• Within 1-3 hours the muscles become
increasingly rigid and the joints freeze
– rigor mortis
• All muscles begin to stiffen simultaneously,
but it is noticeable in smaller muscle groups
first
Rigor Mortis
• Complete rigor takes 10-12 hours to develop
under ideal conditions
– 70-75 degrees Fahrenheit
• The body remains stiff 24-36 hours
• Heavily impacted by temperature and other
environmental conditions, body size, activity
prior to death, etc.
Rigor Mortis
Livor Mortis
• Also known as lividity
• discoloration of the body after death due
to gravitational settling of blood
• Usually noticeable approximately 1 hour
postmortem
• Becomes fixed in about 8-10 hours
• Visible until decomposition changes the
color of the body
Livor Mortis
Livor Mortis
Algor Mortis
• Normal cooling of a body which takes place as
the body equilibrates with the external
temperature
• Occurs at an approximate rate of 1.5 degree F
an hour
– this is obviously dependant on external temperature
– use a formula which includes the room temperature
and the victims anal temperature to determine time
since death
Decomposition
• In general, occurs in stages
– after rigor passes, green discoloration of the skin
become evident
• generally begins on the abdomen about 24 hours after death
– The body will begin to swell (bloat) due to production of
gas by bacteria in the large intestine
• may begin within 96 hours after death, sooner if warm or wet
– As the body bloats, the outer layers of the skin begin to
slip off the body, as will the hair and nails
Decomposition
• Also during bloating the body fluids may purge
through the nose and mouth and other
orifices.
• At about the same time, the blood within
vessels degenerates and darkens, giving the
skin a marbled appearance
• Three Very Gross Pictures Next!!!!!
• You may want to close your eyes and
think of flowers and fluffy puppies
Order of Decomposition
• digestive system: intestines, stomach,
accessory digestive organs, heart, blood,
circulatory system
• air passages and lungs
• kidneys and bladder
• brain and nervous tissues
• skeletal muscles
• connective tissues
Autopsy: Post-Mortem Wrap-Up
Steps Involved:
1. External Examination
a. measurements - length, weight
b. inspection of external surface for injury,
discoloration, “cause of death” signs
2. Opening of Trunk
a. ‘Y’ incision
b. Open rib cage
c. Condition of heart
d. Remove organs
Autopsy: Post-Mortem Wrap-Up
Steps Involved:
3. Remove brain
cut around cranium using
“Stryker saw”
store for 2 weeks in 10%
formaldehyde
4. Closing
Cause of Death:
Examples Seen During Autopsy
Petechial hemorrhage as a result of strangulation
Autopsy - Y incision
Autopsy: Post-Mortem Wrap-Up
• Two Short Videos
–Real Life CSI - Crime Autopsy
–Dr. G - Autopsy
–Real Autopsy Demonstration Video