March 02, 2012

Meet Our Giant Turtle

Last summer the Burke's fossil preparator, Bruce Crowley and a team of volunteers excavated a giant turtle - but finding it was only the beginning.


The fossil was first spotted on this rocky outcrop. Bruce and volunteers dug around the area where the bone was visible to make sure they got every piece of the fossil.

Enough of the bone was showing to tell that they belong to a prehistoric soft-shelled turtle (the family Trionychidae). The geology of the area tells us that it's about 49 million years old.








Bruce wheels in the giant turtle.
The fossil and the rock surrounding it were covered - first with aluminum foil (or paper towel or toilet paper), then with plaster. The aluminum foil prevents the plaster for sticking to any exposed bone, and makes it easier to remove once it's back at the museum.





Inside this plaster jacket are the fossil remains of a 49-million-year-old turtle. But for the moment, it's covered in rock and it's heavy.





Now that the jacket is in the fossil prep lab at the Burke, the team can begin to remove the rock that surrounds the bones.

Once the rock is removed, the turtle could prove to be the biggest fossil turtle in the Burke's collection.


Bruce uses a cast cutter to open the plaster field jacket. The black tube in the upper left of the photo is a vacuum to suck up plaster dust and dirt. Bruce wears a mask to protect his lungs from plaster powder.





The fossil prep setup. Bruce uses a vacuum cleaner to clean up dust in the work area.










After a couple weeks of work, fossil bone is exposed. It may not look like much, but what you see here represents a lot of work.

The sandbags are used as wrist rests while Bruce works on the bone with air-powered "micro jacks" - tiny, miniature, hand-held jack hammers.


In this close-up of the work area, taken about 2 weeks after the field jacket was first opened, you can see part of the fossil bone exposed. The orange stuff in the upper right is glue to keep the rock from splitting while Bruce is working and breaking the fossils inside.

You can see the giant fossil turtle this Saturday at the Burke's annual Dino Day. From 10 am (9 am if you're a Burke member!) to 4 pm, get an up-close look at the turtle and talk to Bruce and other Burke paleontology experts. 

Posted By: Winifred Kehl, Communications