Postmortem Changes to Bone Flashcards
What are the three things that usually cause postmortem changes?
dismemberment, taphonomy, fire
What are the reasons for dismemberment?
- impede identification (remove hands, bash face)
- lack of respect/hatred for decedent
- easier to transport/hide
What are the three instruments that generally cause dismemberment?
cutting, chopping, and chiseling instruments
What are the two types of dismemberment?
localized dismemberments and generalized dismemberments
Localized dismemberments
specific regions dismembered
Generalized dismemberments
across entire body or in logical locations
Why are saws similar to chisels?
the teeth act like individual chisels
Crosscut saws
saw across grain of wood; have angled tip
Rip saws
saw with grain of wood
What are the three types of marks caused by saws on bone?
- superficial false start
- false start kerfs
- sectioned bone cuts
Superficiale false starts
barely nicked it, startled by bone
False start kurfs
metal wiggles and slips, common with handsaws
Sectioned bone cuts
when the cut goes all the way through, useful in determining blade construction and saw type
Kerf
cut marks made by saw
Fine striations indicate
small teeth
Deeper striations indicate
larger deeth
Regular striations indicate
power saw
Irregular striations indicate
handsaw
Rough kerf floor indicate
fewer teeth
Smooth kerf floor indicate
more teeth
Breakaway spur
forms when you saw through most and the last bit snaps off, shows top to bottom motion of saw
TPI
entire teeth per inch
PPI
points per inch
Are serrated knives considered saws?
Yes
What are the three components of saw mark analysis?
full description of cuts, direction of saw cuts, and type of tool
What are the three ways animal scavenging can impact remains?
scatter skeleton, break bones by trampling, remove bone segments by chewing
What are the most typical carnivores involved in scavenging?
dogs and coyotes
Punctures
small holes created by carnivore teeth, not fracture lines
Pits
similar to punctures, but don’t penetrate the cortical surface (from carrying bone)
Scoring
scratches that usually appear as parallel lines (from nails/claws)
Furrows
deeper than scorring, occur at ends of bones
Bones that are ____ to detach are usually taken first.
easy
Do scavengers usually take the cranium?
No
Why do rodents get involved in scavenging?
rodents chew on bones to keep their teeth worn down (and for calcium)
What marks do rodents leave on bones?
flat, square, parallel grooves
What are the signs of weathering?
cracks, peeling and flaking, bone warping, bone bleaching
What effects does the burial have on remains?
cracking/warping (soil weight) and erosion of cortical bone (pH, wind).
Can water damage occur in all bodies of water?
Yes
When can water damage occur?
when the body is moved, when putrefaction/bloating occurs, when individual bones are removed
What does water damage the body through?
hitting rocks, disarticulation, algae straining, or hardening by silt
