A new duck-billed dinosaur, a new crested duck-billed dinosaur, two new horned dinosaurs, four bone beds containing the remains of juvenile and adult dinosaurs, and the largest dinosaur rookery this side of the Pacific Ocean. After collecting an array of specimens from the upper layers of the Two Medicine Formation during the 1985 and 1986 seasons, I decided again to explore its lower, older layers, specifically, those exposed in the southeast corner of the Blackfeet Indian Reservation, along the Two Medicine River, the formation's namesake. Located about sixty miles from Landslide Butte, the area contains sediments representing the entire formation, from bottom to top, some 12 million years of terrestrial deposition on the upland coastal plains. The reason so much of the geological record from the late Cretaceous is accessible there is that the Two Medicine Formation does not lie flat but tilts slightly, the uplifted side facing away from the mountains. During the 1987 sea son I planned to set up a camp near the formation's midsection, almost due south of Cut Bank, so that if we walked east, or downstream, we would encounter older strata, and west, or upstream, younger strata.
Possessing an uncanny sense of direction, that itinerant bone-hound Barnum Brown had passed this way, too, in 1917, unearthing an ornithopod that resembles the late Cretaceous duck-billed dinosaur Gryposaurus, except that its teeth are flatter and broader, like those of Iguanodon, an ornithopod known only from the early Cretaceous. Brown's dinosaur possesses other primitive features as well, including unusually large forelimbs, all of which, taken together, indicate that it might have been an ancestor of some of the duck-billed dinosaurs. That, at least, was what I was led to believe upon examining the skeleton at the American Museum of Natural History in the late 1970s, and it was one of many ideas I hoped to test when we arrived at the Two Medicine River in early June. After reading Brown's hastily written field notes (he often scribbled in the margins of newspapers or scraps torn from paper bags), I was sure I could place my crew within a few miles of his original excavation, but that's all I could be sure of. Any reckoning more precise would be a matter of luck. And as sometimes happens, luck awaited us, in the person of Tom Harwood, gentleman, rancher, and, I've been told, consummate fiddle player. I approached Tom for permission to camp and search for dinosaurs on his property, which encompassed a promising stretch of badlands near the river.
"Young man," he said, "You can look for bones anywhere you care to, but I can't put you up in the spot where I usually put fellas like yourself. That washed away in the '64 flood."
The '64 flood? What did he mean by that? Did he remember where the "fellas" came from, their line of work?
"New York City," Tom replied. "A professor. Had a bunch of college boys with him."
I was dumbfounded. The only other paleontologist who had collected in the region was Barnum Brown. But was that possible? Had Tom met Brown?
"I guess it's been a few years," he said, chuckling to himself, then going on to explain that in 1917 he was seventeen years old. When Brown arrived at the family ranch, young Tom led him to a spot where a fossil jaw with large, flat teeth was located. Brown paid Tom a hundred dollars for his services as a guide and for the specimen. And it was that very specimen that I had studied at the American Museum. Small wonder that paleontologists are a little superstitious.
While Carrie Ancell and the first crew established a camp on Tom Harwood's land I sent a second crew, under Bob's leadership, back to Landslide Butte. Nineteen-eighty-seven brought a considerable expansion in the scope of my research, one made possible by an event that occurred the previous July. In Cut Bank to do our laundry, Bob, Dave Weishampel, and I had stopped at the local tavern for a couple of beers. While there I received a phone message from Mick Hager, at the museum, saying that I should call such-and-such number in Chicago and ask for a fellow named Hope. I figured Hope was a reporter who wanted a story about our fieldwork, so I didn't bother to return his call until I finished my laundry, when I learned that he was instead a representative of the MacArthur Foundation. "You've won a fellowship," Hope declared, with more drama than I could appreciate at the time, adding that I would receive a total of $204,000 over the next five years. Having never heard of the MacArthur Fellowship program and finding it more than a little suspicious that a man named Hope was offering me an enormous amount of money that I was free to spend any way I saw fit, I dismissed the episode as a practical joke.
The first check arrived in early August. I bought a new four-by-four pickup truck to replace the oil-burning, gear-slipping rattletrap I'd been driving all over Montana's back roads in recent years. In short order I also purchased much-needed equipment for the laboratory, including some of the most sophisticated computer gear available. I hired additional staff to oversee the cleaning and restoration of specimens brought back from the field and a parttime artist to provide illustrations, and eventually took on eighteen graduate students. To this day, I don't know how my name came to be included on the list of candidates the MacArthur Foundation considered for fellowships in 1986 or why exactly I was selected, but I'm ever grateful, because it gave me the wherewithal to seed one of the biggest dinosaur research programs in the world.
Buoyed by our success at Landslide Butte, the entirely unexpected MacArthur Fellowship, and my chance meeting with the only man alive who knew exactly where Brown excavated his primitive duckbilled dinosaur, I was in a highly optimistic frame of mind at the outset of the 1987 season. I should've known better. Fortune always goes the way of the wind, goes every which way at once. At Landslide Butte, Bob and his crew had reopened the two new horned dinosaur sites, Dino Ridge Quarry and Canyon Bone Bed, along with Westside Quarry, where we had found the new species of Prosaurolophus. Near the hypacrosaur rookery, which we called Datum Ash Layer, after the volcanic fallout that buried it, they soon found an incomplete adult skeleton and a nest with intact eggs inside. Then, on June 26, across the drainage from Westside Quarry, Bob discovered the partial skull of a Pachycephalosaurus, a very late Cretaceous dinosaur that, despite its superficial resemblance to the ornithopods, was most closely related to the ceratop-sians. Pachycephalosaurus walked on two legs, stood about eight feet tall, and was fifteen feet long. But the dinosaur's defining feature is its skull—a very thick, high-domed braincase, from the back of which protrudes a row of bony nodules, attached to a short snout bearing small spikes.
Pachycephalosaurus fossils are extremely rare. Indeed, the dinosaur is known only from one complete skull, found in Montana in 1940, and a few dome fragments. Bob, understandably excited by his discovery and, as always, eager to share his enthusiasm with others, decided to drive down to the Two Medicine River camp to show the crew there the unusual specimen. I was back in Bozeman at the time. Long after midnight the phone rang. It was Gail McCrimmon, a volunteer from Alberta. "Something's happened to
Bob," she said, her voice oddly hollow, faltering. I held my breath. Gail explained that on the return trip to Landslide Butte earlier that evening Bob had stopped in Cut Bank to get gas, water, and supplies, then continued northward. At about 10 P.M., evidently having fallen asleep, Bob veered off the highway along a gradual turn just outside town. His truck rolled several times and the gas tank burst into flames. There was nothing anyone could do to help. A local rancher drove out to the Landslide Butte camp to tell the crew and to ask them to come into town to identify the body. Bob, my closest friend of more than twenty years, was gone. In a lightninglike instant, he had left us.
As Bob had requested, we marked his death by celebrating life, his and ours. On July i, we held a wake for him at his house in Rudyard, the small town a hundred miles east of Cut Bank where he had taught high school science since graduating from the University of Montana. But it wasn't easy steering clear of the "somber stuff" that he had always considered a wasteful distraction. Besides inspiring a great deal of respect and affection, Bob had been one of the engines that made our summer expeditions go. He had been an ever-present, perpetually confident and confidence-boosting force. With his passing, we were in danger of losing momentum, of losing the will to continue the season. Those of us who had worked with Bob longest, however, knew that nothing would have disappointed him more than that. We knew that we would best honor his memory by doing what he most liked to do—collecting more dinosaur fossils. In the face of hard times Bob usually resorted to hard work, so that was our approach as well. I had already selected Pat Leiggi, my chief preparator, to take Bob's place at Landslide Butte, and he and his crew, eager to find something to take their minds off the loss, didn't wait for the wake to go back to work. Carrie, the other crew, and I had also resumed exploring and collecting along the Two Medicine River, always on the lookout for great blue herons and, especially, pelicans. Imagining that Bob was somewhere nearby, standing watch over the digs, made our newly diminished world easier to bear.
Fortunately, much occurred in the days immediately following Bob's death, keeping both camps very busy. Volunteer Sid Hoffsteder found yet another kind of ceratopsian skull near Canyon Bone Bed. Recovered from a higher, more recent layer of the section than the previous two, it possessed a neck shield with two long spikes thrust backward, like the hook-horned skull, but no nose spike. Instead of a knob in the vicinity of the eyebrows, the third skull had deep, rough gouges. Most unusual, the upper surface of the snout was ridged and gnarled and in all probability had been covered by a horny sheath, or boss, when the animal was alive, just as the horns of sheep and antelope are today. Only one other known horned dinosaur has a nasal boss—Pacbyrhinosaurus, a late Cretaceous herbivore that grew to about thirty feet in length and, like most other horned ceratopsians, is found only in North America, along the Rocky Mountain Front. With the discovery of a third horned dinosaur, later named Achelosaurus horneri, in the upper layers of the Two Medicine Formation, a pattern appeared to be emerging, one, however, whose significance I was only beginning to grasp. When the three Canyon Bone Bed specimens are arranged according to age, the changes to the nasal horn and shield spikes seem to represent incremental developments among related species, as if the three animals belong to the same lineage. What's more, the intervening steps are visible at a level of detail never before observed among dinosaurs.
No sooner had I begun puzzling over that notion when we made a parallel discovery in the lower layers of the Two Medicine Formation, confirming my hunch about Brown's 1917 find. Earlier in the season, only a few dozen feet away from the spot where Tom Harwood had come across the specimen he sold to Brown seventy years earlier, Wendy Sloboda, an amateur collector from Alberta, had found an entire bone bed, now called Hillside Quarry. By the end of June the crew had recovered enough specimens from the site that we could be sure they belonged to the same dinosaur as Brown's, which I eventually named Gryposaurus latidens, or Gryposaurus with wide teeth. As I'd done with the horned dinosaurs of Canyon
Bone Bed, I arranged Iguanodon, Gryposaurus latidens, and other, more recent duck-billed dinosaurs according to age and once again a pattern became evident, especially as regards the teeth. The early Cretaceous Iguanodon's diamond-shaped teeth stand side by side, two rows deep in the dental battery. The similarly shaped teeth of late Cretaceous duck-billed dinosaurs, by contrast, are narrower from front to back than Iguanodon's and, most important, rest within batteries of four or five rows, producing a larger eating surface. Gryposaurus latidens falls midway between the two, with teeth that are narrower than Iguanodon's but an eating surface that is smaller than that of the average duck-billed dinosaur. Coming from the bottom of the Two Medicine Formation, Gryposaurus latidens is of an intermediate age as well, suggesting that the changes to the teeth of the three groups of ornithopods are part of the same progression, among kin, from one generation to another.
As I say, back in 1987 it was unclear what these apparent patterns meant, or how much attention they deserved. We'd gone to the Blackfeet Indian Reservation, after all, to search for further evidence of social behavior among dinosaurs, especially with respect to reproduction and parental care, meaning, of course, more eggs, nests, and babies. Yet in pursuing that interest—specifically, by locating and excavating large monospecific bone beds—we came across all kinds of tangential but nonetheless fascinating information, which would have been foolish to ignore. In a word, our research was evolving, driven by what we happened to dig up no less than what we hoped to dig up. But that is the nature of paleontological fieldwork. It is an opportunistic endeavor, a mixture of design and improvisation, in which being prepared means being prepared to change course when one unexpectedly runs into a dead end or, as in this instance, when circumstances suggest another promising line of inquiry. Though neither Canyon Bone Bed nor Hillside Quarry contained evidence relevant to our ideas about parental behavior, they offered something every bit as valuable—the first, tantalizing clues to a new understanding of dinosaur evolution.
If additional clues lay ahead, however, they would be unearthed outside the Landslide Butte badlands, where, by the end of the 1987 season, we had collected most of the accessible fossils—accessible, that is, without the assistance of large earth-moving equipment, which surely would have disturbed Ricky Reagan's peaceful existence, to say nothing of the impact on his land. At the end of August we loaded a grain truck with our cache of dinosaur bones, including Bob's Pachycephalosaurus, the third horned dinosaur skull from Canyon Bone Bed, and the Gryposaurus latidens remains from Hillside Quarry, and drove back to Bozeman. In addition to the usual winter activities at the museum—cleaning and preparing specimens, studying them with computerized tomography (CT) scans and high-powered microscopes, writing professional papers describing our discoveries—I mounted an effort to hire a combined cook and camp manager. In years past, everyone pitched in and helped with general chores while the job of preparing meals rotated from individual to individual, but that wouldn't do during the 1988 season, when I expected to field my largest crew ever near the Two Medicine River. Mel Jones, who had cooked for pack trains of hunters in the mountains of western Montana, took the job.
In the second week of May we set up camp on the south bank of the river about a quarter mile from Lewis and Clark's so-called Fight Site, where, in 1805, the exploration party shot and killed a Blackfeet warrior, the first and only Indian to die at their hands. With eleven Blackfeet and Sioux tepees, several tents, trailers, and trucks, and a crew that varied between thirty and forty people, our encampment was an impressive sight, especially when viewed from Hillside Quarry, located nearby on a high cliff. Visible, too, from the quarry was a long stretch of the Two Medicine River, as well as much of the wildlife that made the riverine environment their home, including pelicans, which were present in the area when we arrived and remained throughout the summer. Although a year had past since Bob died, starting a season without him, without his energy, was disorienting. He and I had collected dinosaur fossils together since the early seventies, when all that we needed to mount an expe-
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