Paleontology starts with a little childlike wonder
If you were a lucky little kid, your parents took you on a trip to a museum of natural history. There, when you saw the terrifyingly awesome Tyrannosaurus rex, you almost certainly dropped your plans to be a veterinarian or an astronaut, and - if only briefly - dedicated your future to paleontology.
What if you, like Mark Norell of the American Museum of Natural History, had stuck with your dream? What's it like to search for dinosaur bones? Where do scientists look? Is there a right way to dig? Over the next 1,000 words or so, we're going back to the future - the future you conjured in your childhood imagination.
The first step for a budding paleontologist is deciding where to put in his or her shovel. According to Norell, one of the most acclaimed dinosaur-hunters in the field today, young paleontologists face a dilemma. The most reliable place to look for dinosaurs is where other people - either paleontologists or astute farmers and miners - have already found them. But the way to make a name in the field is by digging in places where no one has dug before. Some areas have been off-limits because of political unrest. Others, such as Antarctica, can require dino-hunters to brave decidedly unpleasant living conditions.
Choosing a site has money implications too. "Being a paleontologist is a lot like being a Wall Street analyst," says Norell. "If you keep coming up empty, no one's going to give you any more money." To make matters worse, the odds are terrible. Vertebrate fossils are far less common than their invertebrate cousins.
A scientist can improve those odds by making sure the geology and age of the location are right. The oldest dinosaurs appeared around 230 million years ago, and the last great beasts keeled over 65 million years back. (Of course, you can find a dinosaur nearly anywhere today with a pair of binoculars or some breadcrumbs. Birds are living dinosaurs, at least according to paleontologists.)
Arid areas with fine-grain sediments, such as sand, are best. Lots of big boulders mean that a natural force strong enough to carry a few tons, such as a fast-flowing river, swept through the area at some point, probably destroying everything in its path. Oceans are also low-yield. There are occasional "bloat and float" finds, in which a dinosaur died in the water and drifted out several miles before sinking to the bottom. But those are rare.
Aside from a few satellite images, technology won't help much. According to Norell, who chronicled the life of history's greatest dinosaur hunter in his book, "Barnum Brown: The Man Who Discovered Tyrannosaurus Rex," finding dinosaurs hasn't changed that much since Brown unearthed his most famous fossil in 1902.
Once a paleontologist has found a site and assembled a team of helpers, it's time to handle logistics. A lot of this depends on the site. Paleontologists digging in China - or in north Jersey, or even Prince George's County, where people still find dinosaur bones - usually just bring money for food, accommodations and equipment.
In other areas, researchers have to package up shipping containers of food to sustain a crew of between 10 and 40 people through weeks of digging, along with camping gear, shovels, picks and maybe a jackhammer.
Once on the ground, it's time to start walking. Sites can cover several square miles, so it's impractical to dig the whole thing up. "In 99 percent of cases," says Norell, "you'd never start digging until you found something on the surface."
Many trips come up empty. "If I were exploring a site the size of Manhattan," says Norell, "I would probably spend about two months looking." Sometimes, he laments, "you walk into a beautiful rock formation and think, 'I'm going to clean up.' Then you don't find anything."
If paleontologists do stumble upon something, it's time to start digging. There's no real technique here. You may have seen footage of archaeologists dusting their finds delicately with tiny brushes. That's not how paleontologists work. They establish a wide perimeter around the find to avoid breaking bones, then lift out a large block in one piece. Still, broken bones are part of the business.
As with fishing, they sometimes throw a few back. Norell says, "like an art historian who can tell which painter and studio a particular work came from, a paleontologist knows what he's found." If the fossil is low quality and redundant, they might just let it be.
For a big find, scientists apply some tissue paper, plaster and burlap to keep the block together and protect it during what could be a very long journey over bumpy roads. They can't move blocks heavier than 900 pounds in a truck. With a helicopter, it's possible to carry one-ton blocks.
In the old days, they sent the bones home to be cleaned and assembled. Now fossils belong to the country where they're found. The bones may be analyzed in a different country, but officially they're on loan, and will ultimately have to go back to their country of origin.
In the meantime, there's plenty to do. Helpers use tools from dental, art and woodworking supply shops to carefully separate bone from dirt and rocks. A polymer-based coating will protect them from the elements and can be removed if need be, unlike the shellac of yesteryear.
The vast majority of bones get catalogued and stored in foam-lined boxes. A major find might be assembled, supplemented with bones from other individuals to make a complete skeleton, and mounted for display. But many museums now prefer displaying casts to risking their genuine bones. It would be a shame if an elementary school field trip destroyed something that survived 60 million years of geologic change.
Of course, without those 10-year-olds and their dreams, we might never have found the bones in the first place.
Palmer, a freelance writer living in New York, is a regular contributor to How and Why and to Slate.com's Explainer column.
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