I recently got back from Argentina, and in a few months I’ll be headed out to Wyoming and Utah. And I’m not alone.
Every year, paleontologists all across the world load into vans and trucks and head out into the middle of nowhere. Most of us are huntin’ for dinosaurs.
Unfortunately, there’s a lot of ground to cover. Fortunately, paleontologists know (roughly) where to look. Fossils tend to be found in rocks of very specific types, and different dinosaurs are known from different periods of Earth’s history. So if you want to discover a new dinosaur of a certain type (say, a new, giant meat-eating carcharodontosaur), you go to 100 million year old rocks from low-lying rivers and lakes. Once you’re there, you start lookin’!
As you shuffle around the wastes, you keep your head down and walk around the bottom (base) of the rock formation you predict has the fossils in it. The idea is that if you start finding tiny scraps of bone at the base, since fossils can only roll downhill, there must be a dinosaur in the rocks above you!
So you climb up the hill, looking for bone the whole way. Once you stop finding bone on the surface, it means you’ve probably passed where the fossil is weathering out from. At this point, you want to make sure there IS bone in the ground, and not just an exploded bone on the surface. This means you start gently scraping off the dirt, and digging down with hand-tools to see if you can find any bone sticking out of the rock wall.
Finding a dinosaur in the hill is only the begining. You mark the spot on your map and take notes on exactly what color the rock is, and how high up it is, and then you start bringing your gear. Pickaxes, shovels, jackhammers and big, BIG bags of plaster…
You want to take all of the rock from above and around the skeleton out, while leaving just a little bit of rock directly over the bone for the moment. The idea is to make a flat area using jackhammers/big tools, but to also leave a few inches of rock over the bone to protect it from your heavy equipment. Once you haev the big platform carved out, you start digging down with hand tools.
The man in the foreground is where the cliff’s face used to be. Big dinosaur needs a big hole.
When you dig down and hit the bone directly, you DO NOT take it out! Bone is fragile, and if you remove it then-and-there it will crumble and break. You want to take it back to the museum, where fossil preparators, the heroes of paleontology, can gently take off the rock with steady hands, fine tools and powerful microscopes.
To protect the bones until you get them back to the lab, you make a “jacket”. Dig a deep trench all of the way around the bone, and cover the bone with a layer of paper and then several layers of plaster. This way, the rock around the bone helps keep it in one piece for its journey to the museum.
Let the plaster over the top dry for 1-3 days (longer is better), then flip the jacket and cover the bottom! Flipping the jacket can be stressful, because if you don’t do it both quickly and carefully, the contents can spill out and the fossil can be destroyed.
Once the bottom is dry, you have to carry the entire plaster jacket down off the hill.
Jackets are really heavy. For this one Patagonian dinosaur we removed about 20 jackets with anywhere from half to a half dozen bones in each (skull bones are pretty small). The bigger jackets couldn’t be carried down the hill safely, so we lashed them to a raft made of tires and bent sign and slide them down the sides slooooowly.
Then the REAL work begins. Fossil preparators labor for dozens to hundreds of hours carefully picking away the rock from around the bone with dental tools, tiny, air-powered jackhammers, tweezers and all manner of other fine implement. Once the bone has been carefully cleaned off, and any breaks or fragments glued back in place, the fossil is ready for study and/or display!
Mounted skeleton of Giganotosaurus, a close relative of the dinosaur we are digging in the above pictures, in Villa El Chocon.