Preparing a large fossil is a lot like going on a road trip. It’s all small physical movements mitigated by instinct and enhanced with technology.
With a road trip your eyes are always ahead of you, focusing on the asphalt rolling out towards the horizon. Occasionally you glance in the mirrors or at something interesting sliding by your window but mostly, you watch the road. Your hands and your feet move semi-consciously as you drive, making minute adjustments to the wheel or the gas pedal, kicking at the brakes.
In fossil preparation, your eyes focus on the piece in front of you, watching it, adjusting your hand movements as you chisel away or blast the stone with a fine stream of abrasive powder. Your foot rests on a pedal adjusting that fine stream of powder.
Like on a road trip, it’s easy to get bored and I handle that the same way I handle road trips – I listen to audio books. I listened to books about Fredrick Douglass, the Battle of the Little Big Horn, fish intelligence, water management in the arid west and more this last year. I listened to short stories by Stephen King and Toni Morrison as I worked.
2020 was a big year for fossil preparation for me but it began even earlier, during the summer of 2019. I was volunteering at Aransas National Wildlife Refuge in Texas, to observe alligators as part of research for my first book. I called my boss and he told me about an enormous crocodile fossil from the Green River formation. Little did I know at the time, but I’d spend over a year carefully cleaning the stone off this crocodile’s fossilized skeleton.
A lot of the heavy lifting was done before I was even involved. The slab of stone was cut from the surrounding rock, loaded into a truck and driven from the quarry in Wyoming to a lab in Tucson. That was where I began to work on it.
The first step was to hand chisel away thick pieces of stone covering the fossil itself, something my boss and I did together. The stone from the Green River formation splits easily along planes, and soon we’d removed inches over over burden, something that saved months of work.
Next I took an air scribe, something like a hand held pneumatic jack hammer or chisel and cleaned off more stone. During this phase details of the skeletal anatomy begin to be revealed. Bits of vertebrae peek out through a thin gauze of rock, scutes reveal their strange honey comb pattern. I carefully avoided chipping teeth as much as possible during this phase, in the case of the crocodile, teeth were sharp and some quite fragile. The general shape of the animal’s skeleton started to swim into hazy focus during this stage.
Eventually all the sediment that can be has been removed with the air scribe. The air scribe saves time but if you’re not careful, you can easily damage the fossil. The next stage of fossil preparation is more gentle and thorough.
Air abrasion is messy. After a day of blasting a fossil, my clothes and hair were covered in dolomite, the fine powder we use to clean off the last bit of sediment from a fossil. In the case of the 14 foot long crocodile fossil, all in one piece together, the size required preparation to be done in the open air.
Large fans were set up and the garage doors rolled open in an attempt to blow as much abrasive as possible out of the lab. I wore an industrial mask to protect my lungs and started blasting a fine mist of dolomite from a stylus. Because so much abrasive material moves through the machine, hoses often develop leaks and repairs are necessary. Air abrasion is what reveals all the fine details – textures, shades of rich color become obvious.
Sometimes you find pieces of bone hidden where it wasn’t expected. Often work switches back and forth between air scribe and air abrasion when necessary. Sometimes you discover there is more sediment covering bones than you thought and an air scribe speeds up the process.
After nearly a year to finish the preparation of a crocodile fossil, I find it amazing that fossil preparation was once done purely with hand tools but such were the times. Fossil work today is hard and tedious but a hundred years ago paleontology was back breaking as well as intellectually rigorous work. Nothing makes you appreciate a backhoe more than a few weeks at a modern dinosaur dig.
