Mammoth Site finds new way to prepare old bones

Published: Oct. 19, 2021 at 11:12 AM CDT
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HOT SPRINGS, S.D. (KOTA) - The Mammoth Site is a resting place to roughly 60 mammoths and more than 80 plants and other animals.

Their stories go way back; Dr. Sharon Weaver, curator for The Mammoth Site, is keenly aware of their history: “we’ve been excavating fossils here since 1974, but where we have excavated to - the bottom-most layer that we’ve excavated to - is about 190,000-200,000 years old.”

The bones are more show than tell. They stick out from nearby dirt and are left in situ, or as originally found.

Sometimes, the prehistoric graveyard can have a profound impact on its observers: “I mean, we have people that sometimes come through and do get super emotional. They may cry, because these animals did not have an easy death. This is a very impactful site,” Sharon adds. “It’s a very important site, too, scientifically. You feel a little small, sometimes, looking out into the bone bed.”

Over the last few years, the staff discovered a new problem: Glyptal, an adhesive used to prepare early discoveries in the ‘70s, is creating some unforeseen side effects.

The protective coating, which was brushed onto some specimens decades ago, has hardened overtime and formed a shell over the old bones. This is similar to how chocolate shell topping hardens over ice cream.

Alex Gardner, conservator for the site, says the Glyptal shell leaves the brittle bones exposed to the elements, causing them to slowly crumble underneath and gain a dark or yellow hue over time.

To that end, staff have been using Paraloid, a versatile resin, instead. The substance can adapt to be runny like water or thick like glue, which can be useful in adding a protective layer or fusing certain bones together.

The coating can also be easily removed with acetone like nail polish remover cleans painted nails.

However, rather than spread a protective layer over the outside of fossils, Gardner says they plan to do the opposite: “we need to get this thinner glue inside to stabilize everything from the inside out.”

This is also necessary because some of the more spongy or porous bones needs a substance that can be easily seeped into hard-to-reach or fragile regions of the fossil.

However, removing decades-old build-up is the first obstacle - one that requires a delicate touch, like that of The Mammoth Site Preparator Tabatha Gabay.

“Unfortunately, things do break fairly often. They’re so fragile and brittle that it’s easy for them to break,” Gabay says. “Our goal here is to figure out a very safe and effective way of removing that Glyptal so we don’t damage that skeleton any further and so that we can preserve it.”

Weaver hopes this new method will better preserve a piece of Hot Springs history both today and tomorrow.

“If they’re just falling apart themselves, we lose that information - we lose that piece (of history) ... but that’s always something we’re kind of considering: how can we make sure this resource is available long into the future?” Weaver says.

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