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Preparing dinosaur fossils

Fossil preparators are highly skilled technicians who restore the naturally fractured bones and teeth of fossil to the original state, somewhat like art conservators restore damaged paintings and sculptures.
When fossils arrive from the field, they are encased in plaster jackets and the rock, or matrix, which was deposited around the fossils. Fossil preparation involves cutting open the plaster jacket and removing this matrix surrounding the fossil.
Created by American Museum of Natural History.

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Video transcript

>>JUSTY ALICEA: This, specifically, is  the skull of a dinosaur from a group of   families called Ankylosaurs. They are the  armored dinosaurs. If you could imagine an   armadillo with a lot of spikes all over it. It's  a common misconception that bones are dug in the   field where they're found. What actually happens  is that a researcher will be walking through,   you know, deserted, barren canyon land looking for  bones sticking out of the rocks or weathering out.   A trench is dug around the the specimen. Then  it is wrapped in bandages soaked in plaster,   which is what you see here. So, this is straight  from the field where it was found in Mongolia. For   this kind of material, I would use small tools,  like these needles and things like that, and some   brushes to slowly work off the rock from the bone.  This is soft enough where I can use these kind of   needles and things like that to kind  of gently work it off. We're basically   chipping away till we get to the surface of  the bone and then what we're doing from there   is following the line of the bone around,  gradually removing the rock as we're doing so.   So, what I'm doing is essentially just using  this needle to softly work off the surface   of the rock until I get to the layer of  bone underneath. I've been working on this   piece already about five months already. And  it's probably going to take me another three   or four to get it to the condition that  the researchers want it in. Every year,   these researchers go out to the field and collect  hundreds of specimens and they bring them back   here to the Museum. A lot of times we just find  pieces like you see here. These are just broken   pieces of bones of individual dinosaurs and  things like that. But once in a while we do get   whole dinosaurs and this tells us very much  about the anatomy. This is how we know how   certain dinosaurs were, actually how their  bones were arranged and things like that. Using a silicone rubber we've actually made a mold  of the skull here. And then filling it in with an   epoxy resin we basically make a copy of the skull.  You can see here. And this is research quality.   You can take this under a CT scanner and it will  literally have all of the folds and wrinkles and   cracks of the original specimen. We'll take  about four copies of each bone that we do.   One scientific quality cast, another  one for the home institution. So,   whatever country we've gotten it from,  they'll get a copy of it, as well.   Somebody will sit here and literally block  out these pieces, put them back together   and then mold the whole thing all together  and get this this cast that you see here.