6.
ROCK PICKS AND LASERS
In nearly twenty years of digging whales on every continent, the number of times I had ever found a complete skeleton of a fossil whale was exactly zero. It’s not to say that it doesn’t happen for other people—but it certainly isn’t routine. The rarity of a single, complete fossil whale skeleton is a major aspect of why Cerro Ballena was so confounding: any one of its beautifully preserved skeletons would have been a discovery worthy of celebrating (and agonizing over its salvage); dozens of them yards apart demanded some kind of explanation. And a plan.
Up until I realized the full scope of Cerro Ballena, my fieldwork in Chile had consisted of several years of low-risk science focusing on paleontological essentials: measuring the thickness of fossil-bearing rock sequences at different places throughout the heavily fragmented Caldera Basin and connecting these blocks by linking rock units of similar type and appearance. The end goal was understanding how the Humboldt Current was different in the past.
Playing it safe was a sure bet for delivering results, as a matter of science politics. Our grant funders would demand results from our expedition. Making good on the stated mission mattered to the team, especially to me, as principal investigator—the lead scientist on the grant. Successful delivery meant many publications, ideally in the best journals. As someone just starting his career at a major institution, I felt added pressure to deliver. To my mind, that meant sticking to the plan and tying together a coherent story, not getting mired in too big of a side project with uncertain rewards.
But I couldn’t unsee Cerro Ballena, nor did I want to. It glowed with significance, and it was the kind of unparalleled site that could boost the career of everyone associated with it (should it be successfully reported). Whatever explained the density and completeness of the skeletons was also surely an interesting scientific story, especially for understanding the evolution of whales in ocean ecosystems. But we needed to somehow wrap our minds around essential facts about the site before we could make any conclusions about how Cerro Ballena came to be or what it could tell us.
It seemed obvious that the sheer abundance of big whales at the site—clearly belonging to a species of extinct rorqual—was an important part of the puzzle. Getting more facts about those whales, however, would be daunting. A single whale skeleton might contain as many as two hundred bones, some as heavy as bowling balls or cumbersome as fallen tree limbs, topped off by a skull the size of a grand piano. Collecting a single whale skeleton, even one less complete than those at Cerro Ballena, requires coordinated effort by more than one person, usually over several days. First, you begin with what bone is available on the surface, and get on your hands and knees to inspect it—if it’s not too fragile, there’s no harm in carefully exposing it a bit more, by brushstroke, until you know what’s there. Generally we try to save the time-consuming, detail-oriented work for the lab, but the bones can’t get there unless they’re exhumed from the ground. That means trenching a judicious perimeter around them and then wrapping them in plaster bandages that dry and form a hard cocoon. This protective shell allows us to securely pop the block containing the fossil out of the ground and bring it back to the lab for more work. Straightforward, but time-consuming when you’re dealing with skeletal elements the size of furniture pieces.
When bones are scattered loosely all over the place, as is often the case, then the excavation becomes more like a crime scene, involving a grid (usually string hooked over nails or rebar) overlying the area to map out the position of each bone. The grid makes the relationships among all the bones clear and allows us to plot their locations on a sheet of paper. Then, after plotting, each bone is cataloged and removed individually, or sometimes collectively in small jackets, like the larger blocks. It’s painstaking work.
In the case of Cerro Ballena, the costs of removing each fossil whale were the responsibility of the road-construction company. The company had agreed to pay Tuareg and his museum volunteers to expose, map, and document each skeleton to the best of their abilities, before jacketing the skeletons—sometimes whole, or in pieces as plaster jackets the size of tables and midsize cars. At the largest sizes, plaster bandages and burlap would have failed, so metal support structures had to be added to ensure that the inner fossils were safely transported. While these steps saved the fossils themselves, we were losing crucial information every time a skeleton was pulled from the ground, separating the bones from the context—how they were buried, their orientation, their association with other bones, and so forth—that we would need to answer pressing questions about the origin of this site. The most pressing consideration of all: Tuareg said we had probably less than a month to study the site before all the fossils needed to be removed to make way for the highway’s northbound lane. It was a stunning constraint.
With the specter of the skeletons at Cerro Ballena hanging over all of us, we measured and sampled all of the rock sections that we had originally sought. The next steps, in terms of assembling a single chronology of rocks in the Caldera Basin, would have to be largely lab- or museum-based. We had run out of time to do anything more. I knew we needed to act on Cerro Ballena. I just didn’t know how. We barely had enough time to snap a few photos and measure the rocks at the site—nothing conclusive. It loomed in my mind, a whale-sized, multifaceted question that felt personal: What was I going to do about it?
On the return flight to the United States with Jim and Caro, I tried not to dwell on the logistics and instead thought about the bigger scientific questions. Was it a stranding? A one-time catastrophic event? An accumulation of bodies slowly over time? Testing any possible explanation for how all of these whale skeletons had arrived at the site would require an evaluation, bone by bone, skeleton by skeleton, to determine overall condition, arrangement, the articulation of each bone relative to the others, whether they had been scavenged, and so on. This type of forensic study would take time, definitely more than we had. I wasn’t sure which data were the most important to obtain fastest. The sheer magnitude of the task was overwhelming.
As I watched Jim ease into a window seat with his laptop for the long flight back to the United States from Santiago, I had an idea. If there were some way we could capture the bones digitally, beyond just static images, we might be able to buy time away from the site, back in the lab. I suddenly remembered a recent chance meeting with two people who did exactly that kind of thing.
I first encountered Adam Metallo and Vince Rossi in a windowless photography room in a research wing of the Smithsonian, hunched over the enormous skull of an extinct crocodile relative. They were passing a laser beam over its bony surface using a robotic arm connected to a laptop. Vince straightened to introduce himself, smoothed invisible creases in his untucked shirt, and launched into a demonstration. As he talked, I watched Adam paint light over the croc skull; the data then appeared in real time as a patchwork of surfaces stitched into a 3-D model on the computer screen.
Adam and Vince were part of a then-nascent 3-D digitization program at the Smithsonian, and they were looking for partners at museums throughout the Smithsonian constellation to provide case studies for their work. I thought what they were doing was genuinely interesting, but at the time I wondered what scientific problem scanning was solving. I thought it was more important to have a question first, and let the technology serve that aim. By the time I was thirty thousand feet over South America, poking my airplane-food portion of palate-blistering ravioli, I realized that I’d found that question.
Back at the museum, I did my best to present my quandary to Adam and Vince, convey my excitement, and hope for some kind of fruitful collaboration. In contrast with the traditional field methods in paleontology, it seemed obvious that laser scanning would have incredible advantages at Cerro Ballena. First and most crucially, it was many times faster than the time-consuming and costly steps of drawing grid maps or making large plaster molds with latex. Scanning would also have no physical contact with the fossil, eliminating any risk of damaging the bones when pulling off a latex peel. Second, scanning would create a digital model that was essentially a snapshot in time; there would be no decay of the facsimile, the way a latex peel or even a plastic cast slowly degrades over time. Given the scale of a single fossil whale skeleton, capturing a digital copy seemed like an ideal way to make comparisons across the potentially dozens of skeletons at Cerro Ballena—far easier to overlay or make side-by-side comparisons on a computer screen than pacing from skeleton to skeleton in the real world.
Laser scanning also surpassed the practicalities of other technological solutions. X-rays might perform similarly well, but there was no good way to bring an instrument that produced X-rays, such as a CT scanner, out to field localities. Nor was there any way to fit a thirty-foot whale skeleton in a standard hospital CT scanner. (Only a few CT scanners in the world can handle objects approaching a few feet in the largest dimension.) X-rays would have circumvented line-of-sight issues inherent for very large objects: the small overhangs and deep pockets along the vertebrae and skull pose the same challenges to a laser and camera as they do to a paintbrush full of silicone, because these nooks and crannies can’t always be perfectly captured below the threshold of your application tool.
As it turned out, Cerro Ballena would be the first of many successful collaborative projects in the realm of 3-D digitizing of museum specimens. Adam, Vince, and I became fast friends; I immediately took a shine to their background in exhibit arts—artists and scientists aren’t so different when you consider how creative enterprises see the light of day only when they squeeze past all the barriers of resources, personality, and time. Adam and Vince also knew that there were as many narratives as there were specimens in the Smithsonian’s holdings, and that 3-D had the promise to make those stories accessible and visible.
Once I secured Adam and Vince’s interest in my particular case, Caro and I went about securing funding for a last-minute field season with food, gas, trucks, lodging, and equipment—and airfare for now nearly a dozen people. We made a great team when it came to carefully calibrated funding pitches to the director’s office at the museum, and to National Geographic, which funded part of our original season of fieldwork. As we flexed charm and rhetoric to underscore the urgency of the project, we managed to cobble together enough funds to cover the immediate costs of a return to Chile. In the flurry of activity, it became more and more clear that tackling Cerro Ballena meant moving out of a safe zone into the high-risk, high-reward category of scientific endeavors. For me, a pretenure curator, it was an unnerving consideration. Scientists earn credibility by finishing big projects and delivering results; spending a lot of time and money with nothing to show for it, especially on an international stage, means risking your future—and those of your early-career colleagues too. I didn’t want to expose Caro, Tuareg, and Jim to those kinds of risks any more than myself.
When we returned to Chile, Tuareg was there to greet us; I introduced him to Vince and Adam, saving other concerns for later. We made directly for Cerro Ballena along the Pan-American Highway, arriving less than an hour after our plane had landed near Caldera, in Copiapó. With a week to go before Tuareg’s deadline, we didn’t have time for diversions. We needed laserlike focus.
Tuareg and his team had already made strategic decisions about which whale skeletons to document and remove and which ones to leave intact until we could arrive—less than a dozen, I guessed from a quick survey. In the brief interim, while we were gone, I knew that Tuareg had done the best he could to preserve what was at hand, as the road-construction company quickly scraped away the overlying rocks, down to the level of the highway. As an outsider, I had limited sway in Chilean politics; I wasn’t sure what to expect until we rolled up to the quarries, which had been overlain by sediment only weeks before and now opened into a space about the size of two football fields end to end.
We had two basic approaches at our disposal, with very different logistics: a laser arm scanner (which required elaborate setup, especially with a heavy, shake-proof base to keep its position static during scanning) that collected the geometry of surfaces at submillimeter precision; and handheld, high-end digital cameras, which would collect images to build a 3-D model with software back in the United States. The laser arm scanner and its attendant gear were too cumbersome to move whale to whale and would need to be dedicated to a single skeleton; camera work, on the other hand, could be deployed across multiple skeletons.
One array of three skeletons piled on top of one another was clearly a high priority for photography: an aggregation people at the site had taken to calling La Familia. The two bigger, adult-sized skeletons lay tail to nose, splayed in a V but complete in every way, including even hip bones; joining them, in a small leg across the opening of the V, was a smaller skeleton belonging to a juvenile whale with unfused skull bones. I’m generally loath to use nicknames as a shorthand for individual specimens, mainly because I think that pet names trivialize the hard work that goes into collecting and studying fossils. At Cerro Ballena we used Tuareg’s field numbers across the site, but “La Familia” was a lot more convenient than saying “B21, B22, and B23.” I also had to admit that La Familia conveyed some awe for the oblong, heart-shaped outline of the trio of fossil whales.
Clockwise: B21, B23, and B22—or as they are better known, La Familia
There was no guidebook for the work that we set out to do, and it required a lot of thought, creativity, and trust. We camped out only yards away from the highway, and every eighteen-wheeler screaming downhill reminded us of that impending northbound lane. Tuareg and his team constructed a tent over B33, one of the most perfectly preserved of all the large baleen whales at the site, to shield the equipment and work from the dust and wind. We improvised seating on the largest transport cases, which also doubled as workbenches; Vince and Adam got priority with the only card table, which they used to create a workstation for their souped-up laptops. At one point I paused at the back of one of the field trucks and watched Adam and Vince busy at work with laptops, laser scanners, and tripods while cables and accessories spilled out around them. “You guys are like some kind of laser cowboys,” I said, smiling. Adam grinned in reply and Vince laughed, but they both kept at work. The sound of all the busywork at Cerro Ballena gave me confidence, for the first time, that we might actually pull off this ambitious plan of turning the physical into the digital.
Days and nights melted away in the tent as the cowboys slowly moved from nose to tail, scanning B33. Each pass of the laser arm, like a thick brushstroke, was instantaneously transmitted to the laptop, revealing more and more of the skeleton’s digital avatar on the screen before us. The fine resolution of the entire scan, highlighted in raking light by the computer program, looked like a bas-relief from antiquity. Nothing like it existed, as far as I knew—no fossil skeleton had been scanned in the ground with this kind of detail, and certainly not a fossil whale. I smiled for a moment, thinking how fantastic it was that we could capture and bottle the context of a skeleton like this one. There might be dissertations’ worth of study in the data set from B33 alone. And we had also collected the photography data from all of the other whales, including La Familia.
Later, back at the Smithsonian, the cowboys would take these colossal, dense clouds of scanned data points and photographs and translate them into 3-D models of the whales at Cerro Ballena in incredible detail. The submillimeter precision of B33 (and the slightly coarser millimeter-scale precision of La Familia) was a way to future-proof the 3-D models: we collected information at the highest possible resolution and preserved each rendering at every step of the process. The basic underlying data were also recoverable well into the future by using standard formats for the digital photos and simple text files for x, y, and z coordinates of the scan data. These measures ensured that the time frame for studying the digital facsimiles of Cerro Ballena would extend for years to come.
The 3-D data from Cerro Ballena were mesmerizing to behold on a computer screen, far from the field site; but it’s a whole other experience to 3-D print them, especially at the scale where they fit in your hand. Even today, when I pick up a color 3-D print of them—skeletons that took walking strides to appreciate and comprehend, now rendered compact in my hands—I’m transported back to our days at the site, even to the specific time of day, based on the shadows printed in relief. Even more exciting was the opportunity to 3-D print one of the Cerro Ballena skeletons at large scale, which today anyone can see at the Smithsonian, inside the natural history museum’s learning center auditorium. Thousands of miles away and years removed from our work, I can walk the length of a plastic copy of B33 on a wall, seamlessly stitched together from individual tiles. I can tilt my head to just the right angle to see the skeleton, tinted with some paint, as it would have lain on the ground, and remember our long days beside the highway in the Atacama. These facsimiles tell stories as much as the real thing. More important, they can be shared with anyone who has access to e-mail, a computer screen, or a 3-D printer.
At the site, as Adam and Vince worked away at scanning, I shifted my focus toward the geological and paleontological data that we would need to test any idea about how this graveyard at Cerro Ballena came to be. During our first season, as part of our larger work in the Caldera Basin, we measured the stack of rocks exposed at the site. The stratigraphic column created from this work presents a kind of key that can be used to determine the geologic age of the rocks. The column also provides a basis for interpreting the kind of environments that those rocks represented—the overall setting—when the whales were first deposited at Cerro Ballena.
By the second field season, we had realized something profound about the site: Cerro Ballena wasn’t just one layer of whale skeletons but four, all directly on top of one another. It took us some time to come around to this conclusion, in large part because the Pan-American Highway cuts a long diagonal gash against the horizontal rock units at the site as the road dips to the south. As a consequence of the length of this slope, we never had one complete view of all the layers at the site. From the tent over B33, we could see other whale skeletons to the north that appeared to be higher in the rock section by several feet. But we didn’t know if that was a real feature or the result of the widespread faulting throughout the basin, which might have broken up a single layer into a vertical jumble like uneven blocks of a sidewalk.
A full reading of the layers at Cerro Ballena came only from walking back and forth along the slope, moving up and down in geologic time and tracing out individual layers from skeleton to skeleton alongside the rock wall. This hands-on process let us track the horizontal positions of individual whale skeletons as we went, giving us visceral proof that there were indeed multiple layers of skeletons on top of one another. B33 was in the second layer out of four; directly adjacent to B33, profiled on the new road-cut wall, we could touch still more whale skeletons, unexposed, which were directly on top of it in the rock sequence.
We also quickly realized that we needed Tuareg to help us reconstruct the placement of each whale skeleton in this new context—we were missing which whale came from what layer for everything collected before that insight. For all of his showmanship, Tuareg never failed us as a paleontologist, and we were able to deduce the information from his detailed notes and quarry diagrams. The fact that Cerro Ballena was actually four sites piled directly on top of one another was a stunning revelation for the scientists on our team. It was a piece of the puzzle hiding in plain sight, as important as the completeness or close proximity of each skeleton. Multiple whale-bearing rock layers at the site meant that there might be some unifying cause for why they were deposited in this one particular place—a basic proposition in science, in that repeated patterns tend to be generated by the same underlying process.