7/28/19 1 TRAUMA VS. TAPHONOMY Marcella H. Sorg, PhD, D-ABFA University of Maine Colby 2019 1 NOTE: IMAGES OF IDENTIFIED CASE REMAINS HAVE BEEN REMOVED. DESCRIPTIONS ARE PROVIDED FOR HANDOUT. Terminology ■ Trauma : while person is living or at the time of death – ANTEMORTEM (1-2 weeks before healing is visible; Periosteal reactivity after few days in children (under magnification) (Barbien & Sledzik, 2008) – PERIMORTEM – At or about the time of death. Operationally: lacks signs of healing; bone breaks are influenced by more elasticity, not brittle. ■ Taphonomic modifications occur after death (can be human agency) – POSTMORTEM Colby 2019 Taphonomic modifications ■ Dismemberment ■ Scavenger modifications ■ Fire ■ Water transport ■ Geological forces (e.g., erosion) ■ Weathering ■ Recovery, autopsy ■ Most taphonomic changes are continuous Colby 2019
Transcript
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TRAUMA VS. TAPHONOMY
Marcella H. Sorg, PhD, D-ABFAUniversity of Maine
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NOTE: IMAGES OF IDENTIFIEDCASE REMAINS HAVE BEEN REMOVED.DESCRIPTIONS ARE PROVIDED FOR HANDOUT.
Terminology■ Trauma: while person is living or at the time of
death– ANTEMORTEM (1-2 weeks before healing is visible;
Periosteal reactivity after few days in children (under magnification) (Barbien & Sledzik, 2008)
– PERIMORTEM – At or about the time of death. Operationally: lacks signs of healing; bone breaks are influenced by more elasticity, not brittle.
■ Taphonomic modifications occur after death (can be human agency)– POSTMORTEM
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Taphonomic modifications
■ Dismemberment
■ Scavenger modifications
■ Fire
■ Water transport
■ Geological forces (e.g., erosion)
■ Weathering
■ Recovery, autopsy
■ Most taphonomic changes are continuous
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Anthropologists & pathologists use “perimortem” differently
■ Forensic pathology –more precise■ Detection of hemorrhage (heart still
beating)■ “Perimortem” at or about the moment of
death■ Anthropology --application NOT PRECISE
■ Detecting indicators of moisture & fat loss– “Perimortem” when bone still moist &
elastic enough to “act” fresh biomechanically
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Bone trauma only rarely has evidence of hemorrhage
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(Image of newborn skeletal case with traumatic defect)
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WOUND
Ectocranial View –CLOSE-UP IMAGE OF INFANT PARIETAL
Endocranial view –CLOSE-UP IMAGE OF INFANT PARIETAL
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In the absence of signs of hemorrhage…Was the bone fresh (wet) when the modification happened?
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Indicators of Taphonomicversus Traumatic Status■ Loss of Bone Flexibility and Elasticity■ Fracture pattern
■ Staining■ Desiccation
■ Plastic deformation■ Ruling out taphonomic signatures
■ Place within a sequence of change
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Perimortem to postmortem transition = a continuum■ Looking “fresh” or “wet” (i.e., “perimortem”)
– Can last a long time; depends on context– Related to amount of elasticity remaining,
affecting the biomechanics of fracture– Presence of cartilage, moisture & fat– Elasticity can be lost even if bone stays “wet”
■ Intermediate state between perimortem wetness & postmortem dryness is the problem
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Futile search for universals of postmortem timing in forensics…
Such as…■ How long does it take for a body to decompose?■ How long does it take for a bone to stop acting
fresh?
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Condition depends on context
– Bone retains material properties of being fresh for weeks to months■ Elastic due to presence of cartilage, moisture
& fat (“viscoelastic property”)■ Gradual loss of moisture and fat in most
situations■ Mostly depends on environment (wet vs. dry)
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Type of bone matters
■ Long bone versus flat bone
■ Cortical bone tissue retains elasticity longer than spongy bone
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Fracture Pattern in Long BonesUsually perimortem
– “Spiral” fractures with relatively smooth fracture margins
– “Butterfly” fracturesUsually postmortem (Lack of radial pattern with impact)
– Transverse or step fractures with rougher fracture margins
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Adapted from Wedel & Galloway, 2014, Figure 5-2, p. 64
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Perimortem type spiral fx
But postmortem type step/transverse fxSo probably not perimortem
SAME BONE
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Staining
■ Fracture margin versus adjacent surface■ Fracture margin (cortical bone) exhibits less
stain■ Clearer on long bones
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Staining Staining on perimortem fracture margin on left versus lack of staining on postmortem fracture margin on right. TAPHONOMIC BACKGROUND: Decedent jumped from high bridge into a large, fast-moving river in northern New England, and was transported to and partially buried in a sand bar. Skeletonized body was found in anatomical position 8 years later. Postmortem fracture occurred at time of discovery.
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More recent (postmortem) fxis unstained
Smooth vs. rough fx margins
IMAGE OF PROXIMAL HUMERUS WITH BOTH PERIMORTEM & POSTMORTEM FRACTURE
StainingAnterior view of postmortem sharp force defect on inferior pubic ramus (arrow). With magnification, defect cut walls were found to be unstained), and cortex was stained. BACKGROUND: Decedent missing for ten years was found in northern New England wooded site. Skeletal elements were scattered.
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■ IMAGE OF PUBIC RAMUS
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StainingRe-associated fragments of left innominate, fractured in the perimortem period. TAPHONOMIC BACKGROUND: Decedent was hitchhiking on northern New England highway, and was hit with motor vehicle. Scattered remains were found 5 years later in slightly wooded area 30 feet from highway and down a steep slope adjacent to road shoulder.
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■ IMAGE OF INNOMINATE RECONSTRUCTED FROM TWO FRAGMENTS■ CLOSE-UP SHOWING
STAINED FRACTURE MARGIN
Plastic deformation
■ Plastic deformation is a characteristic of fresh bone that becomes warped due to “slow loading” impact
■ Bending as a result of blunt force, beyond the point where it can bounce back to its original shape.
■ Gunshot projectiles are too rapid for bone to warp
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Plastic Deformation
Close-up of the anterior portion of the fracture showing differential fragment staining and plastic deformation (fragments are slightly warped and do not fit perfectly).
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■ CLOSE-UP IMAGE SHOWING PLASTIC DEFORMATION IN PELVIS
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Desiccation
■ An indication of postmortem status■ Can create defects■ Can modify perimortem defects
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Desiccation cracks ■ TWO IMAGES OF
SCAPULAEComparing desiccation cracks (left) with sharp force trauma (right). TAPHONOMIC BACKGROUND: Scattered skeletal remains (Left) were found in NNE woods; decedent missing 3 years. Partly decomposed & skeletonized remains (Right) found partially submerged in a stream in May after individual had been missing for 1 year.
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Depressed Fracture
■ Depressed fracture with heaving concentric fractures is a pattern characteristic of the perimortem period. Experimental study of hammer blows to 5 fleshed & 5 nonfleshed pig skulls over 12 month postmortem period. Taphonomic change can mimic perimortem fractures (Calce & Rogers 2007)
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Depressed Fracture
Perimortem depressed fracture in frontal bone. Note the bone surrounding the sharp force lesion, including concentric, heaving fractures. TAPHONOMIC BACKGROUND: This is an historic specimen of unknown provenance.
■ Can you rule out carnivore involvement?– Are there carnivore patterns?■ Evisceration■ Extremity units missing■ Long bone end modification■ Spiral fractures (since it is usually in the perimortem
period)
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Rule out scavenger bone modification pattern■ Can mimic blunt force trauma ■ Can occur in antemortem, perimortem or
postmortem period■ Whole pattern recognition
– What is there and what is missing – Extent & type of scatter– Morphology of all modifications in the bone
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Canids: (domestic dogs, coyotes, wolves, foxes) can mimic blunt force trauma■ Depending on the size differential between the
canid and the bone being modified & bite force…– Impact scar or depressed fracture– Spiral fracture in long bone– Comminuted fracture
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NH OCME Apr 12 34
Bear modificationof human femurSpiral fx
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Bear, not coyote, in this case
Canid pattern
■ Punctures■ Pits■ Grooves■ Chipping long bone back from end into marrow
cavity■ Smaller bone may have pits, punctures, &
impacts on opposite sides
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Pit
PitPuncture
Scalloping
Pelvis: canid modification
R/L proximal tibiae: Chipping back to marrow
Pit
PitPuncture
Scalloping
Pelvis: canid modification
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Canid typical sequence
■ Haglund canid modification sequence (Haglund, 1989)– Stage 0 No bony involvement– Stage 1 Ventral thorax damaged and one or
both upper extremities removed– Stage 2 Lower extremity involvement– Stage 3 Only vertebral segments remain
articulated– Stage 4 Total disarticulation
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Defleshing, head
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8 IMAGES OF SKELETAL REMAINS EXPOSED IN WOODLAND STREAM & MODIFIED BY CARNIVORES
2 IMAGES OF SKELETAL REMAINS EXPOSED IN WOODS & MODIFIED BY CARNIVORES
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Carnivore v. Blunt Force Trauma
■ Carnivores can produce blunt force damage– Impact scar + radiating fractures– Spiral fractures– Plastic deformation and warping
■ Ask....– Is the defect demonstrably perimortem?– Was there carnivore access to body?– Is this defect part of an overall known carnivore
pattern or is it isolated/focal?– What are the mechanical limits of the suspected
carnivore jaw in terms of size and mobility?– Is there another likely competing hypothesis for
blunt force? (e.g., fluvial)
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Carnivores v. Sharp Force Trauma
■ Really not an issue if you use the microscope■ SFT: grooves bottoms are V-shaped; U-
shaped with tooth or claw■ Look for SFT weapon class indicators:
machined grooves on kerf walls■ Carnivores can’t do hacking
■ Look for other evidence –e.g., in the clothing
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Dismemberment
■ Pattern of extremity removal or butchery■ Tool marks
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5 IMAGES OF DISMEMBERED REMAINS
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Rodent pattern
■ Usually not confused with perimortem trauma because they like dry bone
■ Haglund, 1997– Short, parallel scrapes– “Windows” scraping and penetrating, then
perforating flat bone– Removal of processes, parts that protrude from
rest of bone, like brow ridges (provides a “purchase” to steady bone with mandible, while maxillary incisors scrape)
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TWO IMAGES OF RODENT MODIFIED CRANIA
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Rodent modification & staining
Probable perimortem crushing blunt force trauma. The main defect border has been modified by rodents, as evidenced by the incisor scraping marks. The fragments from the lateral cranium were scattered in the perimortem period and underwent different exposure to sunlight. TAPHONOMIC BACKGROUND: Decedent was found in the northern New England woods approximately ten years after she went missing.
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■ IMAGE OF RODENT-MODIFIED CRANIUM
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Thermal damage
■ Thermal damage vs trauma■ GSW signature with thermal damage■ SFT signature with thermal damage
■ Bohnert et al, 1997. Retrospective study of 20 cases placed in cremation under observation, and prospective study of 13 fire deaths. No basal skull fx’s observed.
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Sharp force trauma and thermal damagePosterior right oblique view of C1-C6. Transverse processes of C3 and C4 removed with a sharp instrument. Fire damage to C2 & C3 transverse processes, but not cut edge on C3 & C4. Transverse processes of C5 & C6 may have been cut, burned by the fire, or both. TAPHONOMIC BACKGROUND: Decedent was known to have been assaulted with a knife, killed and partially burned.
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■ IMAGE OF CERVICAL SPINE WITH THERMAL DAMAGE AND SHARP FORCE DAMAGE
GSW vs. suture vs. thermal damageReconstruction of burned and fragmented cranium reveals GSW. Close-up of ectocranial surface on bottom left; endocranial surface on bottom right. TAPHONOMIC BACKGROUND: Body recovered in highly burned and fragmented state. Fragments were reconstructed enabling identification of trauma.
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■ IMAGE OF BURNED AND RECONSTRUCTED CRANIUM WITH GSW■ CLOSE-UPS OF
ENDOCRANIAL & ECTOCRANIAL SURFACES
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Macroscopic criteriaPERIMORTEM LESIONS• Bone more elastic• Outline –radial/spiral-
■ When examining bone, must define “perimortem” in taphonomic terms– Period when bone behaves as though it is fresh
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Taphonomic approach needed to differentiate traumatic & postmortem modifications:
■ Context is important: – Documenting access to moisture, heat,
scavengers at the scene
■ Complete inventory is important: – Thorough search & recovery--ability to identify
taphonomic patterns and signatures
■ Thorough documentation of condition is important:– Patterns for each element & region
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References (1)■ L.T. Barbian, P.S. Sledzik, Healing Following Cranial Trauma, Journal of Forensic Sciences. 53 (2008)
263–268.
■ M. Bohnert, T. Rost, M. Faller-Marquardt, D. Ropohl, S. Pollak. Fractures of the base of the skull in charred bodies - post-mortem heat injuries or signs of mechanical traumatisation? Forensic Science International 87:55-62.
■ S.E. Calce, T.L. Rogers, Taphonomic Changes to Blunt Force Trauma: A Preliminary Study*, Journal of Forensic Sciences. 52 (2007) 519–527. doi:10.1111/j.1556-4029.2007.00405.x.
■ A. Cappella, A. Amadasi, E. Castoldi, D. Mazzarelli, D. Gaudio, C. Cattaneo, The Difficult Task of Assessing Perimortem and Postmortem Fractures on the Skeleton: A Blind Text on 210 Fractures of Known Origin, Journal of Forensic Sciences. 59 (2014) 1598–1601. doi:10.1111/1556-4029.12539.
■ A. Cappella, E. Castoldi, C. Sforza, C. Cattaneo. As osteological revisitation of autopsies: comparing anthropological findings on exhumed skeletons to their respective autopsy reports in seven cases. Forensic Science International 244(2014:315.
■ C. Cattaneo, A. Cappella, Distinguishing between peri- and post-mortem trauma on bone, in: E.M.J. Schotsmans, N. Marquez-Grant, S.I. Forbes (Eds.), Taphonomy of Human Remains: Forensic Analysis of the Dead and the Depositional Environment, John Wiley & Sons, Incorporated, 2017.
■ C. Cattaneo, D. Porta, Trauma analysis of skeletal remains, in: Wiley Encyclopedia of Forensic Science, 2009: pp. 1–9.
■ A. Galloway, L. Zephro, V.L. Wedel, Diagnostic Criteria for the Determination of the Timing and Fracture Mechanism, in: Broken Bones: Anthropological Analysis of Blunt Force Trauma, 2nd ed., Charles C. Thomas Springfield, IL, 2014: pp. 47–58.
■ A.E. Green, J.J. Schultz, An Examination of the Transition of Fracture Characteristics in Long Bones from Fresh to Dry in Central Florida: Evaluating the Timing of Injury, Journal of Forensic Sciences. 62 (2017) 282–291. doi:10.1111/1556-4029.13260.
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References (2)■ W.D. Haglund, D.T. Reay, D.R. Swindler, Canid Scavenging/Disarticulation Sequence of Human Remains
in the Pacific Northwest, JFS. 34 (1989) 587–606. doi:10.1520/JFS12679J.
■ W.D. Haglund, Rodents and human remains, in: W.D. Haglund, Sorg (Eds.), Forensic Taphonomy: The Postmortem Fate of Human Remains, CRC Press, Boca Raton, FL, 1997: pp. 405–414.
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