Darren Tanke’s Gorgosaurus preparation 2: into the jacket

Bringing in the jacket

The Gorgosaurus block was brought in the main preparation lab of the Royal Tyrrell Museum today. Its catalogue number is TMP 2009.012.0014. I should explain the numbering system as some don’t understand how it works. TMP = Tyrrell Museum . 2009 = year of collection. 012 = site, in this case a general number for Dinosaur Provincial Park . 14= 14th specimen. So translated this Gorgosaurus is the 14th specimen collected from Dinosaur Provincial Park , in 2009 by the Royal Tyrrell Museum.

All the catalogue data were on the part of the plaster and burlap field jacket which was going to be removed, so I transferred that data to the side of the jacket, rewriting it with a black magic marker. Don’t want to lose that number! Sometimes I will consult catalogue records if I am preparing a specimen unfamiliar to me. Perhaps the collector noted something about the specimen that I cannot see, such as how a certain area is poorly preserved and broken up. Forewarned I can be especially careful when I am digging down to this area. However, as a co-collector of this specimen I know all its little idiosyncrasies so could bypass that step.

The first incision

Then I got ready to open the jacket. Cutting plaster makes a lot of dust so I sprinkled some material (oily sand and sawdust) onto the floor to keep dust levels down and confined so I was not tracking plaster dust all over the museum later on. I got a dust extractor (essentially a giant vacuum cleaner that filters the air) ready to suck up the dust created while cutting. I got a cast cutter- a piece of medical equipment used to cut casts off of broken arms, etc. The blade of this does not spin but rotates back and forth about 5 degrees. As I had only made two plaster/burlap layers on this side of the jacket (to lighten it for the helicopter lift), the cast cutter did quick work- I cut all the way around on the edges in about 10 minutes. I then got some flat screwdrivers, inserted the blade of one into the cut I just made and started to pry up the jacket, moving along, prying and holding up in a stepwise fashion. Within 10 minutes the whole piece popped off. I then vacuumed the dust from the edge of the jacket and threw the cap piece away.

Darren at work with the cutter

The cap is ready to go

The rock had dried out inside the jacket and shrank, forming some deep cracks. This is a common occurrence. I mixed up some dental plaster to the consistency of milk and poured that into the cracks until they filled up. The plaster adds stability to the crack and can be removed as required. More plaster may be added as I work my way down into the rock. The bowl we mix the plaster in is made of rubber- it is easy to clean out, you just wait for the remnants of plaster to harden then you squeeze the bowl and all the plaster breaks free. Most of the rock showing in the jacket now is clay. That I can remove without delay as the specimen itself is inside the white sandstone immediately underneath.

Inside the jacket

Adding some plaster

More to come soon! All photos here and in the series are owned by Darren Tanke and the Royal Tyrrell Museum.

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