Bone Hunt

“I think I’ve found something!” The call rang out from across the quarry. Suddenly, a dozen or so would-be paleontologists—myself included—shifted their mental focus from the small zones of rock immediately in front of them to a new center of attention. Having spent the last few hours using hand tools to grub our way through crumbly rock with little tangible result, we found the idea that someone had actually found something to be exciting indeed.

Nate Murphy, the paleontologist in charge of the dig, strolled over to take a look. “That’s something, all right,” he said. A little more excavation revealed the 3-centimeter-long tip of a theropod dinosaur’s tooth. Considering the age of the rocks that entombed it, Murphy estimated that the meat eater had shed the fragment around 150 million years ago.

This episode, the first thrill on my recent foray into paleontology fieldwork, was by no means the last. Sure, most of those thrills were vicarious. Other folks found many more fossils—and more impressive ones—than I did. Nevertheless, I gained an understanding invaluable to my writing about paleontology—how dinosaur bones start their journey from rock formations into museums.

My invitation from Murphy, research director of the Judith River Dinosaur Institute in Malta, Mont., came late last year. “Have you ever been on a dinosaur dig?” he suddenly asked during a chat at October’s annual meeting of the Society of Vertebrate Paleontology. “You need to understand what goes on in the field.”

As I’d already suspected, extracting fossils from their stony tombs is hard, gritty work. The first step often is literally stumbling across bones that have eroded from a hillside. Then, there’s some detective work tracking those fragments uphill to their source. There’s the backbreaking work of moving tons of rock to expose layers that hold the ancient bones, followed by the painstaking excavation of sometimes fragile remains that haven’t seen the light of day for millions of years.

Most of the time, it’s achingly monotonous. But oh, those moments of excitement!

Sunday, July 2: Members of the dig team gather at noon at a hotel in Billings, Mont. Many stayed elsewhere the night before—some at hotels, others at campsites, a few at their nearby homes.

Our 11-vehicle caravan reaches the dig site, about 160 kilometers north of Billings, in a little more than 2 hours. The highways and gravel roads that we follow pass through a variety of landscapes, including ranchland dotted with small oil wells and sparse forests.

We pull into our campsite and pile out of the cars into rolling pastureland. All eyes are immediately drawn to a grim, gray scar on the other side of a small valley, a quarry where Murphy and other paleontologists have, on and off during the past couple of years, spent time unearthing the remains of two large dinosaurs. We are tempted to rush over there, but there is a campsite to set up.

Dave Hein, owner of the ranch, has mowed an area where we can pitch the cook tent and park the supply trailers. Portable toilets are towed to the far side of the campsite, and the camp showers are assembled next to the water truck—compared with digs in more-remote locations, this expedition will be posh, I am told. I will be privileged enough to sleep in the back of a truck.

While the other campers set up their tents, I chat with Hein to find out more about the site. Some of his wife’s ancestors—five brothers from England, from whom Hein’s 5E Ranch gets its name—settled here about a century ago. In 1985, Hein first found chips of fossilized bone lying on a hillside.

Then in 2003, he and his son used some earthmoving equipment at the site and came across a few large bones. Realizing the possible importance of the find, they turned to local experts. After a series of phone calls, Hein spoke to Murphy, who has since excavated bones at the site each summer.

Around the campfire after dinner, at Murphy’s behest, we take turns introducing ourselves. Our group of 33 includes teenagers, retirees, museum volunteers, geologists, paleontologists, and even a theology professor. Only about half of us have been on digs before, and we are all itching to get our hands dirty.

We spend the rest of the evening in song, 2 hours of guitar- and coyote-accompanied ballads, folk tunes, and sing-along classics such as “Dead Skunk in the Middle of the Road.”

Long after we stumble off to our sleeping bags, the coyotes are still singing.

Monday, July 3: We gather at the site to learn some basic digging skills. The standard-issue tools are awls—think ice picks on steroids—and stiff paintbrushes. We aren’t to use the awls like ice picks, however—a motion that Murphy refers to as “Hitchcocking.”

Instead, we are to gently pry apart layers of rock, brushing away the debris and inspecting our work zone regularly so that we won’t damage any fossil before we realize it’s there. Done right, it’s slow going. Poke, pry, sweep, repeat. Fill up a gallon-size scoop with debris, and then dump it in a bucket. Six or eight scoops fill a bucket, and six or eight buckets fill a wheelbarrow. Roll the wheelbarrow downhill, empty it, return to your little section of strata. Fill, roll, empty, repeat. A ton of rock makes a pile much smaller than you’d think.

Late in the morning, the theropod tooth comes to light. No other bones of a meat eater have been found at this site, says Murphy.

In 2004, Murphy and his colleagues finished unearthing the bones that Hein had found, including four neck vertebrae, a portion of a femur, and almost a dozen ribs. They identified the dinosaur as a long-necked herbivore called a sauropod, and the team nicknamed it Ralph, after an earlier member of Hein’s family whose homestead had been just a few hundred meters from where the Heins had found the dinosaur.

During the 2005 field season, the paleontologists unearthed seven more neck vertebrae and eventually uncovered Ralph’s skull, upside down and half a meter away from the rest of him. Ralph’s head had probably rotted off, rolled into that position, and then been buried by an ancient stream. Sauropod skulls are exceedingly rare, says Murphy.

The tooth tip that our team found may have broken off as a theropod fed on Ralph’s carcass. The femur fragment found 2 years ago showed signs of having been gnawed on, Murphy notes.

After our lunch, further excavations near the tooth reveal a 20-cm-long fragment of another of Ralph’s ribs. A few other, heavily eroded pieces of dinosaur bone turn up, but Murphy says that they probably aren’t Ralph’s because his fossil bones are usually in good condition.

We also come across plant fossils that may provide clues about the environment in which Ralph died. Cris E. Merta, a geologist from Sheboygan, Wis., notes that at first glance, the plants appear to have been similar to modern-day reeds, so the area may once have been a wetland.

The rocks that hold Ralph probably were deposited as sediment sometime between 150 million and 147 million years ago, says Melissa V. Connely, a geologist from Casper College in Wyoming.

Tuesday, July 4: After breakfast, Murphy takes a few of us over to a neighboring ranch. Last year’s dig team found a few bones there beneath a light coating of sand, dirt, and bone chips. About 50 m away, the group discovered the end of a 2-m-long femur sticking out from the ground. Our job today is to remove the plaster jacket that has protected that bone during the winter—from harsh weather as well as from the sharp hooves of grazing cows. We’ll then dig farther around the bone so that the fossil can be removed later in the week.

Because the rock is much harder here than it is at the Ralph quarry, we must learn the basics of using small air hammers driven by compressed air. We take turns shattering rock.

As we work several centimeters away from the femur, we’re constantly on the lookout for previously undiscovered bones from the same dinosaur. We also have to be careful not to damage the crumbly end of the bone that had been exposed to the elements before its discovery.

The rock at this site breaks into pieces that are thumbnail-size or larger, so it’s a challenge to brush them out of the way as we work. Nevertheless, all goes well until one of the team members doesn’t lift his heel quite high enough as he steps backward across the femur. Whoops! Because much of the outer surface of the bone had been bonded together with liquid adhesives, a piece of that veneer the size of a legal pad sloughs off, taking a couple of handfuls of bone chips with it.

We stand frozen, mouths agape, and when we turn off the air hammer, the silence is deafening. Then, a series of quietly muttered curses. After taking a minute or so to recover a bit of composure, one of the team members sheepishly retrieves Murphy from the bone site nearby. We explain what happened, plead contrition, and brace ourselves for the worst. Obviously disappointed, Murphy stands mute for a few seconds and then says, “That’s OK. If anyone ever tells you they’ve never broken a [dinosaur] bone, then they haven’t really been digging.”

Although this is the first truly sunny day of the week, we work under a cloud for the rest of the day.

Except for lunch: As a special treat, Hein has invited the dig team to join his extended family for a Fourth of July barbecue, replete with especially refreshing lemonade and watermelon. Someone breaks out a family photo album and shows us pictures of Ralph, the namesake of the sauropod we’re excavating.

All too soon, though, we’re back at the neighboring ranch, where we break up more rock. We come upon a few more fossils, which fortunately remain intact.

After dinner, around the campfire, we learn that discoveries by other team members at the Ralph quarry have slowed to a standstill. However, a few participants roaming the hills about 150 m away have found some fragments of bone, tracked them back to their hillside source, and dug out what appear to be a few tail vertebrae and fragments of a spike from a stegosaur.

Wednesday, July 5: Today, the center of attention shifts from Ralph to the new stegosaur. Further excavation yields more tail vertebrae as well as some limb and foot bones. This site, which stretches along the hillside no more than 6 m or so, is a flurry of pick-and-shovel activity. The small shelf that we’ve dug into the hillside can barely accommodate all the dig-team members who want to get in on the action.

I take pictures and do my best to stay out of the way. On the third day of the dig, the novelty of excavation has worn off and muscle aches have set in.

That evening, we’re rewarded by exciting news. Parts of the stegosaur’s tail vertebrae that we excavated weren’t fused as they would be in an adult, so the creature may have been a juvenile, says Susannah Maidment, a paleontologist from the University of Cambridge in England.

Other features of the bones suggest that they represent Hesperosaurus—an exciting possibility, she notes, because only four other fossils of this stegosaur species have been discovered, all of which are in private collections. The one Hesperosaurus that has been described in a journal paper didn’t include limb bones, such as the one we’ve found.

Thursday, July 6: Today at the cozy stegosaur quarry, my fellow diggers and I expose many new bones, including the end of a large one, possibly a femur, that seems to extend quite a distance into the hill.

At the dig site on the neighboring ranch, other team members uncover a tangle of bones that will have to be left for another expedition to excavate.

Despite the daylong efforts of the two team members who remain faithful to the Ralph site, no bones are forthcoming.

“You know what you did today?” Murphy asks them at dinnertime. “You just closed that quarry. You put Ralph to rest.”

Friday, July 7: This morning is a frenzy of activity. We have only half a day in the field, during which we must extract some fossils, jacket others, break camp, and head back to civilization.

While some team members sketch the layout of the bones, the less artistic of us—myself included—work with compasses and measuring tapes. A team leader at each site assigns a code number to each bone or assembly, and someone records location data. Small, free-floating bones are wrapped in aluminum foil and labeled. Larger bones are tightly swathed in aluminum foil, then several layers of wet paper towels, then an outer coating of plaster-soaked burlap. Wrestling a fragile, several-hundred-pound lump of stone, bone, and plaster down a steep hill and into the back of a truck is challenging, to say the least.

Midafternoon, we head south to Billings. There, for the first time in a week, we can take a shower that is hot and lasts longer than 6 minutes. Then, we get together for dinner at a restaurant. At our final meal as a group, we each speak a few words about the experiences that we’ve had.

Murphy closes out the speeches by telling us how well our diverse group has listened, learned, and come together as a team.

He plans to immortalize Ralph this fall in a journal paper, giving him a scientific name that will distinguish him in academic circles as a new species. That article will represent a lot of hard work, Murphy notes, adding that we should all proudly consider ourselves a part of the dinosaur-discovery team.