Did the sloths freeze?

If we knew the season in which the sloths died could that help tell us how they died?  Does dying in the winter leave traces in fossils that dying in the summer doesn’t?  The Iceman Murder case offers an intriguing idea for detecting freezing in fresh tissue. In 1983 Pennsylvania police found a corpse tightly wrapped in plastic bags dumped along a mountain road.  Medical examiners performing the autopsy noticed an unusual pattern of decomposition and odor, and suggested to skeptical police that the victim had been kept frozen somewhere since he had disappeared over two years earlier. The examiners had spotted cavities in the victim’s tissues where the doctors hypothesized ice crystals had grow, distorting the surrounding tissue and leaving holes they called “ice crystal artifacts.” Their discovery eventually helped convict a New Jersey contract killer.

I’m wondering: 1) Do ice crystal artifacts form in bone?  2) If so, what do the holes look like and can they be distinguished from the post-mortem recrystallization of apatite that also enlarges the cavities? 3) Is the warping of the bone by the ice different in fresh bone versus weathered bone ? 4) Can we distinguish immediate post-mortem freezing from ice artifacts that form in subsequent winters?   5) Would ice crystal artifacts be more likely in one particular bone?  6) Will a thin-section of the bone show them?   7) What other clues does dying in winter leave?


Zugibe, FT and Costello, JT. 1993. The Iceman Murder:  One of a series of contract murders. Journal of Forensic Science 38: 1404-1408.

Did the sloths drown?

How do three sloths die all at the same time? One of my crazier ideas is maybe by falling through ice and drowning.   I read a lot of forensic science literature hoping for an “Aah ha” moment when I find a technique that might give us a clue.  We obviously can’t look for fluid in the sloths’ lungs, but forensic scientists have come up with an intriguing alternative–diatoms. 

Drowning victims often inhale diatoms as they fight for breath.  They enter the bloodstream when the alveoli in the lungs rupture and then disperse throughout the body as the heart keeps beating, winding up in well-vascularized organs and tissues, including bone marrow (Peabody, 1999).  Medical examiners find them inside the femur about 1/3 of the time (Polanen, 1998).   We do have an adult sloth femur, and diatoms fossilize just fine, but even if we found some inside, there’s the problem of proving they didn’t enter through small cracks as the bone sat exposed or during excavation.   The femur was sealed in clay for 10,000 years but weathering and/or frost fractured it into almost 50 pieces and that’s a lot of cracks in the bone and holes in my theory.  Could we sacrifice another bone that isn’t so broken. . . a rib of the toddler perhaps?  Are ribs as well-vascularized as femurs?   There’s another problem–it’s not that unusual to find diatoms even in the absence of drowning.  Swimmers inhale them all the time.  If our sloth was like Mark Spitz, he/she was loaded with them. . . .    Dave   


Peabody, AJ.  1999. Forensic Science and Diatoms.  In The Diatoms:  Applications for the Environmental and Earth Sciences, EF Stoermer and JP Smol eds. Ch. 20,  pp. 413-418.

Polanen, MS. 1998. Diatoms and homicide, Forensic Science International 91: 29-34.