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I've given you all quite a bit of information on the dinosaurs themselves, but I've yet to really go into detail about how paleontological fieldwork is operated, nor the processes that create the remnants of these ancient life forms.

Hopefully this diary will give you a basic rundown!

Fieldwork is absolutely essential to the existence and continuation of the paleontological field--unlike many branches of physics, chemistry, and many other sciences, without fieldwork paleontology would essentially not exist. We would know as little about where we came from (both our species and life as a whole) as we did several thousand years ago.

To truly understand the core nature of what we do during the fieldwork process, it's first best to have a basic grasp of the notion of geologic time (the vast time scales we paleontologists must deal with almost every day). The scientific concept of an ancient Earth itself is a very recent invention (admittedly, in the western hemisphere--many Asian cultures believed the universe to have been timeless and ancient) --first proposed by a scientist by the name of James Hutton in 1785 in a book called Theory of the Earth; or an Investigation of the Laws observable in the Composition, Dissolution, and Restoration of Land upon the Globe. In it, he observed that many of the processes that helped create the rocks around him can be seen today, and that these processes create sedimentary layers of rock over time on an Earth in which "we find no vestige of a beginning, no prospect of an end."

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Life, as far as our definition will carry us, appeared roughly 3.7 billion years ago; in the form of simple single-celled organisms very similar to many of the bacteria we know of today. And it has been in this unicellular form that most of life has existed throughout the aeons. Through a mergence of genetic theory and through studying the fossil record, multi-cellular life is thought to have most likely appeared nearly 600 million years ago, with the first traceable fossils appearing during an event dubbed the 'Cambrian Explosion' roughly 540-530 million years ago, in which multi-cellular life rapidly diversified into a multitude of forms.

The dinosaurs, the subject of this series of diaries, are a relatively recent breed through time--first appearing roughly 230 million years ago, during the Triassic Period, when all the continents were fused together into a massive super continent by the name of Pangea (it is thought that Eoraptor, a small bipedal dinosaur found in Argentina may be very closely related to the common ancestor of all of the Dinosauria).

And over time, Pangea started to fragment--first in two parts (when the Tethys seaway opened between now Asia, Europe, and North america and the rest of the world), then other splits as time went on. As the continents split and became isolated, so did the dinosaurs--and isolation means rapid diversification and evolution.

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In order to become fossilized, many specific conditions must occur--a subject must die, and become buried in sand or mud relatively quickly. Oftentimes scavengers or other forces will scatter the bones to the four winds (part of the reason that so few complete skeletons are discovered--most of the time, once bones are exposed they're gone in days). Therefore, most remains are very fragmentary.

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After the subject has been buried, it must remain covered for a vast period of time--slowly, water will seep through the rocks and steadily replace each of the minerals inside the bone (though sometimes ancient remnants can be traced--proteins, etc.), rendering it a rock copy of the bone that once was.

As time goes on, deposited layers stack on top of each other--each met by the forces of erosion and tectonics. To discover a fossil, you must first be in the proper types of rock to bear fossil life (sedimentary deposits!), and it must have enough exposed and tilted upward to see what may lie within (without tectonics and volcanic forces molding the Earth, we would see nothing but recent rock formations).

And because we can determine the age and type of certain rock formations, we can pick and choose which are likely to hold certain types of fossils--this is where the field work begins.

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Once a field crew has been gathered together, with all the supplies packed, you find a place to camp relatively near the localities that you will be working in. After looking at geologic maps to understand where you are in time, you also need to know where you are in locality--permission to prospect for fossils is essential, and not doing so makes one susceptible to legal hell.

With a prospective area in view, prospecting begins--when prospecting, it's usually best to follow a certain strategy to cover the area as efficiently as possible. You're walking very slowly, almost as a Buddhist monk in meditation might. Your focus is on the ground, developing a search image for the specific coloration of the fossils in a given locality (different rock types tend to have chemical differences which changes the composition and color of the fossils you are seeking). Sometimes you will see little fragments of bone--these can be a clue if you know how to use them!

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Because most fossils are found in locations that have a great amount of erosion, when they are exposed they tend to fall apart quickly, sometimes rolling down a hillside from the actual layer the bones appear in. When you find a series of fragments, you try to trace it--find where in the area they are coming from. If you see a portion of bone sticking from the inside of the rockface, this may well be it!

To give an idea, this probable duckbill dinosaur femur was found with only roughly a centimeter of weathered bone exposed.

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Then you slowly work your way into the wall (starting from the top and working your way down), being sure to not undercut the fossils as they lie. If the bone seems to be in decent shape, you will then dig an evaluation pit, testing to see if there are more fossils in the locality (1 meter x 1 meter is generally fantastic for size).

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If there are more fossils, you will slowly work your way back into the wall, exposing (but not fully uncovering) each bone in the locality (often using easily dissolvable glues to help preserve the bones when exposed).

Here scientific information is essential--'what are the GPS coordinates? how are the bones spread about? Are there multiple species in the area? Are there any signs of predation, like fractured teeth?'. As the bones are steadily uncovered (using anything from dental picks to jackhammers to even dynamite), you map their position for later study. With all the necessary geologic information and any of the taphonomic information you can divine (how it may have died, and what happened to it after it died--where it was when fossilization occurred, whether it was slowly or rapidly buried, whether it was scavenged, etc.), it's time to extract the fossils.

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The method of fossil extraction has changed almost none in the 100+ years that it's been used by paleontologists--cover the fossil (whether a single bone or entire skeleton) with paper, foil, or something similar, and slowly place strips of plastered burlap over the surface (same idea as casting a broken bone), doing all you can to jacket not only the top, but below the fossil as well (sometimes tunneling below the fossil is essential). If you do it right, you should be able to flip the jacket over without damaging the fossil inside (sometimes flipping it can take some heavy equipment--some jackets have been known to weigh half a ton or more).

Periodic breaks are essential when exposed to the rigors of paleontology--sometimes you are isolated nearly a hundred miles from civilization (in this photo... 10 miles from civilization), in temperature ranging well over 100º F.

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You then load the jacket (sometimes creating a top covering of plaster) into a truck (or carry it with a helicopter!) and take it back to the lab to clean and study.

Hope you enjoy, and feel free to tip and rec away!

Stay tuned for the regular series this coming Wednesday.

Originally posted to Username4242 on Sat Sep 05, 2009 at 12:00 PM PDT.

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