Natural Acts: A Sidelong View of Science and Nature - David Quammen (1996)


The Excavation of Jack Horner

“I DON’T GIVE A SHIT what killed the dinosaurs,” says John R. Horner. Strange talk for an eminent paleontologist, but not out of character for this particular one. He is exaggerating his natural brusqueness only a little, in the interest of stressing a point. “They dominated the earth for 140 million years. Let’s stop asking why they failed and try to figure out why they succeeded so well.” From Horner’s perspective, the entire Mesozoic era—during which the dinosaurs appeared, flourished, diversified, rose to supremacy among all terrestrial creatures, and then, somewhat abruptly, disappeared—is a Horatio Alger story, not a murder mystery.

Jack Horner’s perspective is unconventional but authoritative. His recent fossil discoveries, and the surprising deductions toward which those fossils have led him, are being followed raptly by paleontologists all over the world. With his scruffy beard, longish hair, balding pate, he looks like a skinnier and younger version of the actor Warren Oates. On location, let’s say, for a good-humored film about rowdy and disreputable prospectors. But in fact Horner is one of a trio of men—John Ostrom and Robert Bakker are the others—who during the past fifteen years have been drastically reshaping our understanding of dinosaurs. Ostrom is a venerable professor at Yale. Bakker has lately gone from Harvard to Johns Hopkins. Meanwhile Jack Horner sits, wearing a plaid flannel shirt and beaten-down running shoes, in the basement of a small museum in a place called Bozeman, Montana.

Like Richard Leakey, with his study of early mankind in northern Kenya, Horner has stepped suddenly into the front rank of scientists in his field despite a near-total lack of academic credentials. He never bothered to finish college. Never went to grad school. Doesn’t read German or Russian. Knows almost nothing about computers. Unlike Leakey, Horner did not even have the advantage of famous scientist parents; his family owned a gravel-and-concrete business in Shelby, Montana. Horner is simply a brilliant and dogged bone-hunter, a field man, a natural, with a keen brain for imagining the ecological particulars of an age 70 million years gone. He has a nose for fossils and a head full of provocative ideas.

On a bare hillside not far from the Teton River in northwestern Montana, Horner and his field associates have unearthed a nest, roughly six feet across, containing the bones of eleven baby dinosaurs. In the same vicinity they have also found other nests, several more babies, and the fossilized remains of more than three hundred dinosaur eggs. Throughout the whole history of fossil collection, dinosaur eggs and juveniles have remained breathtakingly rare; no other nest full of hatchlings has ever been found. Consequently, there has been a tantalizing absence of just that sort of evidence necessary to answer certain crucial questions—questions about dinosaurian breeding habits, patterns and rates of growth, behavior among others of their kind. Jack Horner now has that sort of evidence.

Based on his finds, Horner believes that at least one group of dinosaurs were sociable, relatively intelligent, warm-blooded, and solicitous toward their own infant offspring. It’s a little like announcing five centuries ago that the Earth isn’t flat after all.

Warm-bloodedness, nesting in colonies, and extended parental care are all generally nonreptilian attributes, associated rather with mammals and birds. Reptiles are cold-blooded. They don’t (except in rare and disputable cases) tend their young. They don’t show advanced social behavior. Reptiles as we know them just don’t act in the manner that Horner’s nest-field seems to indicate.

But maybe the dinosaurs were not nearly so reptilian as tradition, and eight generations of paleontologists, have decreed. Maybe, suggests Jack Horner, they were something utterly different.

In more senses than one, Jack Horner grew up among dinosaurs.

The wild country of Montana has always been a bone-digger’s paradise, partly because its hillsides and gulches have remained almost undisturbed by human development, more basically because this happened to be a place where great numbers of dinosaurs lived and died and where the sedimentary deposits in which their bones became fossilized have latterly been lifted and cracked open near the landscape’s surface. Toward the end of the Cretaceous period, 70 million years ago, what is now the Midwest and the Great Plains was covered with a vast inland seaway, with central Montana elevated slightly along its western seacoast. Dinosaurs thrived in that swampy coastal zone, and when an individual died, sediments washing down from the newly burgeoning Rocky Mountains were liable to bury it. Finally the seaway withdrew, and the Cretaceous sediments were overlain with more recent strata; as subsequent epochs passed, erosion cut down through those strata, crustal pressures buckled and tilted the land, and in many places the Cretaceous deposits were reexposed to daylight. The result is a rich hunting ground for fossils, an enormous boneyard dating from exactly that time at which the dinosaurs hit their peak.

Back in 1855, the first dinosaur fossils to be found and described in the western hemisphere were taken from beds along the Judith River, not far from Fort Benton, Montana. In 1902, the modern world’s first glimpse of Tyrannosaurus rex came from a dig near Jordan, south of Fort Peck. Jack Horner spent his boyhood at large in this terrain. He found his own first dinosaur bone when he was eight. A systematic kid, he used white paint to label the fist-sized chunk as specimen “104-A” among a boy’s box of fossils.

“Did you save that bone?”

“Yup,” Horner says.

“Do you still have it?”


“What is it? What part of what sort of animal?”

“I don’t have the slightest idea.”

Horner struggled through Shelby’s only high school, and it would be understatement to say that in the classroom he showed no promise of future scientific renown. Languages, for some reason, were especially a problem. “Took me two years to manage a D in Latin One.” Nevertheless he went on to the university, down at Missoula, hoping to do a degree in geology. His father harbored a dream, on Jack’s behalf, of the career of a mining engineer. Jack himself was still dreaming about fossils. More specifically, about dinosaur fossils.

“Dinosaurs are really neat animals,” he says even now, shamelessly ingenuous in his enthusiasm. “I mean, dinosaurs are really neat animals.” Often enough he discusses them in the present tense, hypothesizing details about certain species or families as would any wildlife biologist: “A baby hadrosaur has very little to protect it.”

But his initial try at the university ended sourly. “I’m a product of the sixties,” Horner says with a glint of perverse pride—and his personal details support that self-analysis, since there’s no better way to qualify as a true child of those times than by what befell him next. He flunked out of college in 1965 and was immediately drafted by the marines.

“Everybody thought that the Marines didn’t draft. Remember? That’s what I thought too. The marines?

They sent him through something called “para-frog” training in Okinawa, where Horner was taught to leap out of airplanes over water, wearing a parachute on one part of his body and scuba tanks on another. Characteristically upbeat about personal matters, he counts himself lucky: Despite the training, he was never ordered to jump into an ocean during combat. Instead he jumped into jungle. Most of his thirteen months in Vietnam were spent on “force recon” duty. He would be dropped into the DMZ or some other feverish corner of Vietnamese jungle, with a small team or alone, carrying minimal firepower but a strong radio, and simply stay out there, discreetly, avoiding combat but reporting back south about whomever and whatever he saw.

During one of these solitary patrols, near Quang Tri, just south of the DMZ, he encountered a pair of North Vietnamese students. They were taking instruction at a Buddhist temple. Walking out of the jungle, Horner had seen the temple and was curious. He set his rifle down at the front door, because that seemed the courteous thing, and entered. Several Buddhist monks were there, with this pair of students; the monks were teaching them English and a smattering of biological sciences. The two students, Horner recalls, were the first people in all of Vietnam—Vietnamese or American—with whom he could talk. “Reallytalk. About more than hat size,” says Horner. “Or what an M-16 could do to the human body. ‘Yew ever see what a M-16 kin do to the human body?’ That was always a favorite. So these two students, well, we just started talking. They were, literally, the most intelligent people I met in Vietnam.” He told them a little about himself. Told them he was from Shelby, Montana. One of the North Vietnamese students said, “Is that close to Butte?”

The best Vietnam duty of all, to Horner’s taste, was when he was left by himself to spend a week or two on “recon station,” manning some unprotected little lookout post in the midst of some ungodly forward zone. “I liked being alone in the jungle,” he explains. Surrounded by wild animals and crazy vegetation. A course of nature study. Not so different, he claims, from being home in the outback of Montana. Then one day he called in an artillery barrage but gave the wrong coordinates and collected a leg full of shrapnel when the American cannons shelled him instead of the enemy.

After Vietnam, Horner went back to the University of Montana, floundering as hopelessly as before. He was still fascinated by geology and paleontology, but for a degree in those subjects he was required also to pass courses in math, liberal arts, and a couple of foreign languages. The language requirements in particular were daunting. “I was in Russian class for three days before I figured out it was second term.” At one juncture, Horner recalls, his grade-point average was so low it could be rounded off to zero. Out again, in again, out again, yet during all these years of frustrating academic travail, Horner was still going back up each summer, or whenever possible, to the Cretaceous formations in central Montana. He was digging and collecting with a fanaticism derived from sheer enjoyment. His determination, his love for being outdoors on the Montana landscape, his gift for reading rock, his stamina for crawling around in coulees on bruised hands and knees for hours at a time with finely focused attention—all these were making him a highly experienced field paleontologist, whatever the college records might say.

In 1973 he left the university altogether and began driving a gravel truck. Stone is a leitmotif throughout Horner’s life.

Not long thereafter he moved up to an eighteen-wheel tractor-trailer rig, hauling tanks full of liquid fertilizer all over the state. He was paid by the day, but there was one incentive for making good time. “I always kept an eye open for Cretaceous rock. When I’d come to what seemed like a fossilly area, I’d just stop, unhook my trailer, and drive off across the badlands in that tractor. To look for dinosaur bones.” Yet in Horner’s mind the truck driving, even on these terms, was never more than an interim situation. During the same period he was mailing job-query letters to every paleontological museum in the country.

In 1975 he was hired by Princeton University to work as a fossil preparator (the paleontological equivalent of a dental hygienist), cleaning and gluing specimens that had been found by other people and were to be studied by other people. Faculty scientists, folk with Ph.D.’s. Horner was abundantly overqualified as a preparator, having done the same sort of chores in support of his own private studies for most of the past two decades. Nevertheless he stayed at Princeton for seven years, polishing his skills, learning the ways of museum work, earning a little autonomy, expanding his role by increments, and getting up and down the East Coast for a close look at every important dinosaur collection from Harvard to the Smithsonian. He also spent his vacations each summer out in Montana, gathering more fossils from the gulches and bluffs he knew well and thereby greatly enriching the Princeton collection.

One other significant matter was unearthed during those Princeton years, not a fossil but a fact. Thanks to a campus poster and then an exam, Horner learned for the first time that he suffered—and always had—from dyslexia. That cast some light on the inaptitude for languages, the academic struggles, the strong preference for fieldwork. Words on a page shifted and twisted and tangled themselves before Jack Horner’s eyes. But a bone was a thing of solidity and eloquence.

In 1978, still under the Princeton aegis, he went back to northwestern Montana, back to the same geologic formation where he had found 104-A, back to a bone-hunting partner named Bob Makela whom he had known since the time in Missoula, and together these two aging hippies made a world-class paleontological discovery.

Throughout human history until the late eighteenth century, mankind had no inkling that any such beasts as the dinosaurs had ever existed. Fossil skulls had turned up in a few places—Scythian gold mines of the seventh century B.C., for instance—but had either been ignored, left unexplained, or ascribed to mythical beasts such as the griffin. Only in 1841 did an Englishman coin the word “Dinosauria,” lumping certain weird, newfound fossils into a category whose name translates as “terrible lizards.” Actually they had been neither lizards (a distinct group of reptiles, unlike either dinosaurs or crocodilians) nor, most of them, very terrible. Many were large herbivores, pacific creatures making their livings in roughly the same way as a modern moose, or an elephant, or a giraffe. Even Tyrannosaurus rex may have been less the ferocious and implacable predator, as commonly portrayed, than a lazy and opportunistic omnivore, feeding on carrion or weakened animals or whatever was most convenient, as a grizzly bear does today. But for another 120 years, the conventional view of dinosaurs, both in popular presentations (like Disney’s Fantasia) and among scientists, remained unshaken. According to that view, the meat-eating species were fierce predators that walked erect on hind legs; the vegetarians were huge gawkish dolts, slow-moving and vulnerable; and all of them were simply magnified variations on the anatomy and physiology of a lizard. Cold-blooded. Mentally dim. Lacking any hint of advanced social behavior.

Finally a few scientists rebelled. That traditional view was not only unsupported by fossil evidence, they said; it was downright self-contradictory.

In 1969, John Ostrom told a conference of paleontologists: “The evidence indicates that erect posture and locomotion probably are not possible without high metabolism and high uniform temperature.” About the same time Armand de Ricqlès, a bone specialist in Paris, noticed that the internal structure of many dinosaur bones seemed to resemble mammal bones more closely than lizard bones. During the next several years Robert Bakker assembled a fuller framework of evidence that pointed the same way and published a pair of revolutionary papers in the journal Nature. According to Bakker, the dinosaurs had been warm-blooded. Some of them, to help maintain their thermal stability, had even developed an insulating layer of feathers. In their physiology, and most likely too in their behavior, they were advanced far beyond any lizard on Earth today. In fact, argued Bakker, they should not even be included among the reptiles. These animals had evolved into something distinct. Furthermore, wrote Bakker, “the dinosaurs never died out completely. One group still lives. We call them birds.”

Following this line of thought, what Jack Horner and Bob Makela found on that Montana hillside was a great teeming dinosaur rookery. They had the first evidence of extended parental care, nesting in colonies, and elaborate social behavior (three attributes linking dinosaurs with birds) that was ever uncovered to human view.

Horner calls the site Egg Mountain, in a spirit of ironic but grateful homage. Actually it is only a gentle knoll, one among many out in this rolling terrain of sparse scrubby grass and hillocks and coulees cutting down into a fossil-rich layer of sedimentary rock known as the Willow Creek Anticline. The real mountains loom up in the west, a towering wall of dark peaks and cliff faces not more than a dozen miles off, snow-covered nine months of each year. That stretch of mountains, called the Sawtooth Range, is the easternmost front of the Rockies along this northern part of their length, the very juncture line where the great midland prairies come to a sudden halt, running smack up against the roofbeam of the continent. A few miles up the gravel road from Horner’s Egg Mountain is another anomaly, Pine Butte Swamp, now protected by the Nature Conservancy because of its ecological uniqueness, a northern fenland of wolf willow and bog bean tucked flush against the base of the Rocky Mountain Front. The Pine Butte area is interesting to a biologist for forty reasons but noteworthy to any layman for one thing: It is the only place in the lower forty-eight states where Ursus arctos, once the most formidable beast on the American landscape, still ventures down onto prairie.

“This is the last place in America,” says Jack Horner, “that has the grizzly bear still in its original habitat. Out on the plains. Do you know what it’s like to be on your knees, looking for dinosaur bones—and at the same time you have to look over your shoulder, watching for grizzly?” His face contorts to a lopsided smile. “It’s exciting.” Bears wander over occasionally from Pine Butte to forage for roots or hunt rodents on the hillsides around Egg Mountain. “You come across a paw print, a fresh print, like eight inches long. And that land out there is just open. Nowhere to go. Not a tree to climb for miles.” Another large grin.

Horner was on his knees like that, watching for small bones in the dirt and for big furry shapes over his shoulder, when he and Bob Makela made their historic discovery. On the side of Egg Mountain, in a bowl-shaped depression of brown mudstone, they found the skeletons of eleven baby dinosaurs of the Hadrosauridae family. The hadrosaurs were a group of semiaquatic herbivores, also called “duck-billed” dinosaurs for the slightly comical shape of their plant-gathering jaws, and though adult hadrosaurs were well known from Montana and elsewhere, neither complete juvenile specimens nor eggs had ever been found. Close by the first eleven were another four skeletons of the same type and size.

The depression was unmistakably a nest. Patterns of deep wear on the teeth showed that these babies had been feeding, and for a longish period—yet here they were, in a crowded jumble, still clinging to the cradle. They seemed to have died from neglect; suddenly orphaned, perhaps, at an age when they weren’t yet capable of going out to shift for themselves. In a paper published in Nature, Horner and Makela wrote: “The fact that 15 baby hadrosaurs had been feeding, and had stayed together for a period of time, indicates that some form of parental care was administered for, if the young were confined to the nest, food must have been brought to them.” If so, those young hadrosaurs and their doting parents were unlike any reptiles known in the world today.

Horner and Makela described the new species and named it Maiasaura peeblesorum. The peeblesorum was in thanks to a family named Peebles, ranchers on whose land the find had been made. Maiasaura, according to Horner, means “good-mother reptile.”

The excavations on Egg Mountain and in the surrounding area have continued for seven years, with no sign yet that this rich vein of fossils is even beginning to play out. More nests have turned up, more juveniles, and at least three hundred whole or partial eggs. Adults of Maiasaura peeblesorum have been found, as well as portions of adults from two other dinosaur species, one of which seems to have been a smaller carnivore, a swift creature that may have preyed upon young Maiasaura, snatching babies out of the nest when there was a lapse of parental protection. And along a certain ridge above Egg Mountain, stretching for more than a mile, is what appears to be a continuous, staggeringly abundant deposit of hadrosaur bones. Three thousand pieces have already been taken from one little trench; by extrapolation, the entire ridge deposit might contain several million. That sheer volume of contemporaneous fossils suggests that a vast herd of hadrosaurs, hundreds of animals, once gathered here sociably in a huge clamorous breeding colony, a rookery, finding security in numbers for themselves and their nestlings, in much the way penguins do today.

In 1982, Horner left Princeton. He accepted a position as curator of paleontology at the Museum of the Rockies, a modest institution connected with Montana State University, in Bozeman. The salary is meager. The library resources in paleontology at MSU are meager. The walls have no ivy. It’s a museum where hadrosaur specimens share their end of the basement with a dry old Conestoga wagon. All of which is fine with Horner, who simply wanted to get back to Montana. The editors of Nature, in London, will not worry about his return address.

Through the winters—and out here they are long ones—he now studies his specimens, writes papers, teaches. Then in early June he moves north, with his teepee, to a campsite near Egg Mountain. In company with his old friend Makela (a science teacher at the only high school in Rudyard, Montana) and a few dozen assisting volunteers, he digs and scratches at the ground. The camp’s crucial field-season supplies include a rented jackhammer, short-handle picks, ice awls, delicate brushes, and 150 cases of beer. For three months Horner is at large in the wild among Maiasaura peeblesorum, Tyrannosaurus rex, and the grizzly.

I asked Jack Horner if he could imagine any situation in life that he might prefer to the one he occupies now. He thought for a moment, carefully, and then said: “No.”