Identifying human versus non-human
skeletal remains in the field
Amy E. Kelly
Forensic Investigator
Coconino County Medical Examiner’s Office
Human vs. Non-human
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In modern forensic cases, 25-30% of the
presented cases are non-human in origin.
Access to and using a comprehensive comparative
collection is necessary.
Using a variety of literature in the field is helpful
and an easy and efficient means to improve
animal vs. human identification (Cruz-Uribe and
Klein 1994, Gilbert 1990, Ubelaker 1989).
If in any doubt, GPS, photograph and describe the
specimen and “scene” before moving or collecting
the remains and bringing it to the CCME office for
analysis. If appropriate, call me or the CCME
investigator on-call.
Human vs. Non-human
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The first question that should be asked is “Is it bone?”
and not wood, shell or plastic or rock.
If yes, is it cranial or post-cranial? (cranial bones are
usually thin, flat or even irregular in structure; look for
sinuses, sutures or sockets)
Post-cranial bones are typically long, skinny and can be
flat. Exceptions are the bones of the hands and feet,
vertebrae and the pelves.
Then, look to see if the bone is whole or fragmented.
Also, are the bones adult in age or juvenile? (Fused or
unfused epiphyses)
And lastly but most importantly, could this be human?
Human vs. Non-human
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Most mammalian bones share similar morphological
features between species. The exceptions are marine
mammals and some unusual critters like tree sloths.
The primary difference is size. However some animals,
such as deer, have bones that are very close in size to an
adult human.
Other mammals that cause confusion are bear and
raccoon for their paws (Klepinger 2006). Bear paws look
similar to adult hands and raccoon paws are easily
confused for children’s hands.
Human vs. Non-human
Which hand is human versus bear?
Human vs. Non-human
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Human versus raccoon
Human vs. Non-human
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Easy identifications
Human vs. Non-human
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But what if you come across bones like these?
Human vs. Non-human
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Humans: bipedal
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Pelvis is broad and shallow (bowl-shaped)
The femur is the longest bone in the body with a single linea aspera
The tibia and fibula are separate bones and the tibia is triangular in
cross-section with a small tibial tuberosity
Long and narrow foot with multiple bones for bipediality
Other mammals: Quadrupedal (mostly)
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Pelvis is long and narrow
The femur is short relative to the body size. If the femur’s length is
comparable to an adult human femur, the diameter may be twice as
thick as a human femur (i.e., cow) with a double or plateau linea aspera
The tibia and fibula are often fused and the tibia is more rounded in
cross-section with a large tibial tuberosity or longitudinal ridge.
Legs of larger mammals are modified toes and fingers for speed and
agility
Human vs. Non-human
Vertebrae
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Humans:
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Large, broad and flat vertebral body
Short spinous process (2-3 inches at the most)
Sacrum is triangular in shape and composed of 5 fused
vertebrae, which are broad compared to length and flattened
anteriorly-posteriorly
Other mammals:
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Small vertebral body, often convex on one side and concave on
the other
Long spinous process (>6 inches in some larger mammals)
Sacrum is long and narrow with fewer fused vertebrae (3-4)
Human vs. Non-human
Forelimbs
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Humans:
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Designed for rotation (i.e., throwing, swinging)
Long axis of scapula is perpendicular to scapular spine, which is why it’s
triangular shaped
Clavicle present
Humerus, radius and ulna are not weight bearing so they are not robust. Ulna
and radius not fused
Large thumb
Other mammals:
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Designed for front-back stride
Long axis of scapula is parallel to scapular spine, which is why it’s rectangular
shaped
Clavicle absent in most non-human mammals
Humerus, radius and ulna are weight bearing and robust. Ulna and radius are
often fused to support these weight bearing limbs
Small thumb, even on mammals with similar hands (bear and raccoon)
Human vs. Non-human
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Juvenile Remains
 The most common human bones to be mistaken for animal
bones are bones from infants.
 The ends of the long bones, bones of the hands and feet
and clavicle are not fused
 These unfused bones have indistinct edges
 Multiple ossification centers and unfused epiphyses increase
the number of bones in infants and children
 Epiphyses (the ends of long bones) when separated from
the rest of the skeleton do not look human to the untrained
eye
 Long bones are thinner in cross-section
 Cranial bones can separate and lack the diploe structure, are
uniform in thickness and can be confused with tortoise
carapace. Petrous portion is separate in infants and due to
it’s dense nature, often survives burial better
 Can be confused with smaller mammals such as raccoon,
rabbit or even bird
Human vs. Non-human
Human vs. Non-human
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Mandibles from infants
Petrous bones circled
Human vs. Non-human
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Human infant and fetal bones, recovered from a burial
Human vs. Non-human
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Fragmented and burned remains are more challenging to
correctly identify than intact remains for distinguishing
between human and non-human remains
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Ids can be done macroscopically by morphology**
Ids can be done microscopically (histological examination)
**For our purpose, we only need to discuss
macroscopic analysis
Human vs. Non-human
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Skull Fragments?
Human vs. Non-human
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Fragmentary and burnt bison bones.
Human vs. Non-human
Traumatized and burned pig bones
Human vs. Non-human
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Macroscopic characteristics: cortical bone much thicker
in animal long bones than in human; humeral and
femoral cortical thickness in humans is about ¼ of total
diameter
Bone macroscopic characteristics: cranial bone diploe
relative to cranial cortical (tabular) bone is thinner in
animals compared to humans
Human vs. Non-human
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Review:
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Ask first, “Is it bone?”
Ask second, “Could it be human and
why?” (i.e., context, size/shape of
bones, do the bones fit bipedal
locomotion?)
Have some reference material to
aide in more accurate assessment of
human versus animal (I can provide
photocopies)
If in doubt, no matter how much,
GPS, photograph and document the
remains, then collect or call me or
the on-call investigator
Human vs. Non-human
Call me directly if you ever come upon this…
Human vs. Non-human
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Thanks to the following:
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Staff at CCME for support while I write lectures and play with
bones.
CCSO CI and SAR for all your hard work and selfless dedication
to helping victims and their families with the multitude of hours
and energy invested to ensure recovery.
My dear friends and boyfriend who watch my child so I can
present these lectures.
For Joe