This was my second task at Dinosaur Farm in 1996: putting together a Trionyx turtle shell from a thousand tiny pieces (note my ridiculous hair). I had no diagram to work from, other than Julie's grey plasticene turtle (next to my elbow in the picture),, but I did have a constant stream of museum visitors, each expecting me to laugh at their "it's-like-a jigsaw,-but-without-the-picture" jokes.

Before starting I had no clue as to what turtles looked like inside, but by the end of a couple of weeks, I was a master of Trionyx morphology: able to tell where a piece belonged just by the orientation of the surface texture! Sadly the turtle wasn't all that complete, but not too bad (specimen from Thorness Bay, Isle of Wight, Oligocene).

This is my paleolab in Urumqi, China. While working for the Sino-German expedition, I helped set up the prep facilities. We brought air-chisels from Europe, but everything else had to be purchased in the city. After a few false starts we found an honest merchant who sold compressors and airlines. My power supply in this garage was inconsistent and blew the compressor's fuse, so we visited the store a few more times.

Here I am using my trusty ARO to clean up the ulna of a huge Mamenchisaurus, possibly the biggest dinosaur from Asia. This specimen was the subject of a talk I coauthored (Wings et al, SVP2007)

I've used alot of different air-chisels, and they all vary in what they are good for, and how they are designed to work.

I started out back in the early 90's with the Desoutter VP2-X (second from top) which uses a spring to control the vibrations of the stylus shaft. This allows the stylus tip to move in and out of the housing rather more than what you see in air-chisels that use the O-ring system (all others shown here). Additional movement of the tip means that it is easier to damage fragile fossils, especially as the Desoutter creates more vibrations than other models. It does have advantages though: it will run reliably at much lower pressures than the other units: around 60psi works ok. It never stalls if pressure drops (although it will become less powerful). It is great for blasting apart conglomerates. It has a forward-projecting air exit hole, which can be very handy for blowing away matrix as you prep a specimen.. although of course, it will also blow away any fragments of the specimen you accidentally break off, so you might prefer a unit with a laterally-projecting air hole. It is underpowered compared to the others, although if you crank up the pressure to a similar operating level (90psi or so), it will be more powerful, but difficult to use reliably due to some serious vibrations.

The Chicago Pneumatic CP-9361 (top) is the workhorse air-chisel used in most institutions. It uses a variant of the double-O-ring system to control the position of the stylus, and as such has low vibrations. CPs have a handy speed control at the back of the unit, allowing you to easily regulate the power output. I have seen some wonderfully prepared specimens using the CP: it is a very versatile unit, allowing you to shift bulk matrix, or turn the power down for more delicate work.. you could see it as a drawback that the unit has an oddly shaped stylus tip, and it does use higher pressure than the Desoutter, but not so high as the ARO. It is also one of the quieter units, making a low buzzing noise.

The ARO 8315-B (middle) is a good tool. It uses the double-O-ring sytem to control the stylus, so has very little vibration, and is good for fragile fossils. The stylus is small and precise, although the unit itself is quite bulky, so you sometimes need a bit of room to work: i.e. not so useful when dealing with the intricate pleurocoels of sauropod vertebrae. Variants of this model are available from a couple of manufacturers. The Paleo-ARO (second from bottom) is my preferred weapon of choice. It is notably more powerful than the standard ARO, and has a sturdier carbide stylus, with a longer reach (I use varied stylus lengths, the photo is just an example). All AROs need pretty high pressures and alot of lubricant to keep them working properly, and will stall or grossly underperform if pressure is too low (rendering them more or less useless). They also scream like a banshee when you use them: noone will be able to hear or talk around someone with one of these out in the open.

The Microjack series (bottom) are made by Paleotools and are basically scaled down versions of the ARO, using the double-O-ring system. These come in 6 progressively smaller sizes and are made for especially delicate work, producing extremely low vibrations. They do their job well, but need very high pressure to work (I find at least 90psi, and preferably over 100psi) or else they will buck and stall almost all the time. Like an ARO, they need alot of lubricant, and make a surprising squealing noise.

A problem with all air-chisel units is the eventual wear of the stylus hole in the housing tip, caused by the constant vibration of the stylus itself. Any wear increases the lateral movement of the stylus, which creates larger vibrations: potentially damaging your fossil, and increases the rate at which the housing and stylus are worn. Replace the housing at the first sign of wear, maybe keeping your old housing for rough work that does not need precision. Also note potential health hazards of using vibrating tools for sustained periods .

Sandstone disaggregation using DMSO

Triplehorn (2002) described the use of Dimethyl Sulfoxide in disaggregation of terrestrial sandstones, apparently by attacking kaolinite in the cement. At the end of 2007 I finally bought some DMSO (about $30 a gallon incl. shipping). I haven't yet run any samples.. mainly 'cause I am waiting for warmer temperatures (DMSO freezes at ~50F), but from Triplehorn's descriptions, this could be a remarkable method for retrieving fossils from terrestrial sandstones. Triplehorn & Blake (2001) used DMSO to extract delicate barite crystals from matrix for sedimentological analysis.

When I finally run some disaggreation tests I will post pictures here.

NOTE: DMSO has certain health hazards. read Triplehorn (2002) for full details before trying this method.

Triplehorn, D.M., (2002) An easy way to remove fossils from sandstones: DMSO disaggregation, J. Paleontology, 76(2): 394-395

The greatest field knife ever?

For a long time I didn't use knives in the field: but in the right sediment (generally clays and unconsoldiated mudstones), they are the best tool around.. so it became a quest of mine to find the ultimate field knife: something with a short sturdy blade, very cheap (since it is going to be shoved into dirt), and preferably hammerable. Generally I use cheap buck-knives: but these are usually folding, and get damaged quickly.

Anyway, I was recommended to use an oyster knife by Steve Sweetman a few years ago, so I bought one on Ebay for my dad (in case it turned out to be real rubbish, I could lay the blame on him). As it happens, they rock! The one pictured on the left was the exact same style as I bought for my dad.. it cost a couple of pounds (~$4). I'm not sure if the guard around the blade helps or not, but I figure it could be removed pretty easy. Of course, you can't hammer these, but for close hand work they're great.

Epoxy dribbles

HINT: if you get epoxy resin dribbling down your fossil from overspill, resist the temptation to dab it up immediately with a paper towel (it will invariably end up smeared everywhere, obscuring surface detail. Wait a few minutes until it becomes slightly set, to a rubber like consistency, and just peel it off, or wait until it sets hard and prep it off with an air-chisel (only recommended for hard fossils).

PVA glue in mustard bottles

Polyvinyl acetate (PVA) is a synthetic polymer that dissolves in acetone, and is used for preserving fossils both in the field and the lab.

In Montana I learnt that old squeezable yellow mustard bottles make extremely cheap and effective field containers for PVA. This is a very simple tip, but it made applying PVA in the field so much easier. The nozzle tips that screw open allow you to regulate the size of the aperture, so you can just drip PVA precisely, or squirt it over the surface fast with the nozzle fully open.

...and if you really like this tip, you can dress up as a mustard bottle for halloween

Some links for good preparation websites: