Comments on: Did the sloths freeze?

By: Pete Eyheralde

Pete Eyheralde — Fri, 23 May 2008 02:27:10 +0000

Holmes, I think I’ve got a deer leg or two still in the freezer from last year. These are from a car hit deer I put down in fall of 06 -it was a warm day so I couldn’t hang him -just quick quartered it and threw him in the deep freeze. I was thinking I’d roast them over the fire for some party this summer, but I could donate them for good science:) I’ve got the lower legs and feet of several bison I’ve butchered in the deep freeze too if you could use those.
- Pete

By: admin

admin — Wed, 14 May 2008 16:48:13 +0000

Good idea. We may not need to wait a year. I don’t think longevity in the freezer is going to contribute to crystal growth as much as SLOW temperature changes. Zugibe and Costello note that slow freezing AND thawing cause enormous ice crystal artifacts to grow. When pathologists do tissue thin-sections they use liquid nitrogen to rapidly freeze the sample and avoid ice crystals entirely. We may want to use a home freezer with an autodefrosting feature rather than our walk-in museum freezer. We’ll have to think about how we simulate the mass of the sloth, especially warming up. Fast thawing will defeat the purpose.

By: Holmes Semken

Holmes Semken — Tue, 13 May 2008 21:10:55 +0000

I think that the freezing explanation is wide open for a volunteer project. I propose that we get a cow humerus from the meat market, have a student make a thin section at both ends, freeze it for at least a semester and then make another section for comparison. It should then go back into the freezer and come out again for annual checkups. I am sure that I can provide a weathered bison bone for parallel treatment. Does the museum have a volunteer that would be interested? Perhaps one of the dig volunteers would like to do this also. Better yet, some are deer hunters and probably have deer or elk that has been in a freezer for more than a year. That would be the fast track!