On June 30 the attention of North America`s leading fossil workers will focus on a conference room in the Field Museum of Natural History, where a youthful researcher will present the ”Origin and Early Evolution of Aves.”
The subject is the origin of birds, the occasion the North American Paleontological Convention and the speaker Paul Sereno of the University of Chicago, one of the brightest lights in an explosive field of research-dinosaurs.
Sereno is no stranger to the Field Museum. He`s advising on the extensive remodeling of its Life Through Time evolution halls, soon to feature a sculpture of one of Sereno`s dinosaur discoveries. And Sereno has played the Field Museum, to a very different crowd from the one he will face two weeks from Tuesday.
One night last spring a crowd of 600 filled the cavernous auditorium of the museum to hear ”The Life and Death of Dinosaurs” told by two of the most esteemed scientific names in Chicago. The death part was ably handled by the foghorn-voiced evolutionary biologist David Raup. Addressing the life of dinosaurs was Sereno, a curly-haired, square-jawed man who looks more like an undergraduate athlete than Raup`s fellow professor at the University of Chicago. Only 34, Sereno has already investigated our favorite fossil animals in a globe-trotting fashion unrivaled in decades.
In a divisive discipline filled with mediagenic presences, Sereno is one man for whom praise flows freely. ”He`s the next superstar in paleontology,” says University of Pennsylvania dinosaur scientist Peter Dodson. ”Sereno is the one young guy who does it all, in the lab and in the field,” says self-professed heretical dinosaur paleontologist Robert Bakker.
It is Sereno who opens the proceedings this spring night, with a slide-and film-illustrated lecture that touches on the mess that popular culture has made of evolution (from pictures of Raquel Welch as a cavewoman to ads for dinosaur ravioli). Soon enough, he turns to recent discoveries that have revolutionized dinosaur science, more than a few of which have been his own.
Only weeks before, the peripatetic paleontologist had led several of his students on a jaunt to Texas` Big Bend National Park, on the Mexican border. They had a day to explore a refuge that has been scoured for dinosaur bones for more than 40 years; soon after they arrived, one of Sereno`s students came upon a wedge of bone. As the students dug away the surrounding orange mud, it became apparent to Sereno that they had found a dinosaur skull. Hours later, they had excavated an entire skull, 5 feet long, the first ever discovered at the park. The three-pronged head belonged to an as-yet-undiscovered species of a horned dinosaur genus, Chasmosaurus, and is the most southerly find of its kind in the world.
Within days, the discovery was trumpeted by newspapers around the country. But even after telling the story many times, Sereno still revels in the rarity of the discovery. ”I guess if you have only one day, you find it in one day. Incredible!” He does not, however, dwell on this triumph. He has too many others with which to regale his rapt museum audience, and he launches into a travelogue of fossil hunts from Argentina to the Sahara to Mongolia. As he openly states: ”The Creationists will kill me for this, but we are playing God. We get to create new species. It`s an incredible thrill.”
Spoken like a fossil-lover. But unlike many of his colleagues, Sereno did not grow up a dinosaur fanatic. He was raised in Naperville, the son of a mail carrier and an art teacher, and was more interested in painting than in paleontology. Today his small apartment, within bicycling distance for Sereno from his campus office, is chockablock with charcoal sketches, still-lifes and dark abstractions.
His family was, however, a highly academic one (his brother and four sisters have all pursued graduate studies). ”It was down to the wire after high school, whether to pursue evolutionary biology or studio art,” Sereno recalls.
His older brother, Martin, had a deciding influence on Sereno`s early career choice. A multitalented philosopher and neurobiologist, Martin was then involved in paleontology. After Paul did his undergraduate work at Northern Illinois University, he tagged along when Martin visited Columbia University`s paleontology program at the American Museum (which had graduated Harvard`s Stephen Jay Gould) and did his postgraduate study at Columbia. He says: ”I never recovered from that visit. A seven-story building stuffed with fossils, expeditions to the four corners of the Earth-who could ask for anything more?”
Sereno joined his first expedition (to Howe Island, Australia) the next year, to look for giant Ice Age tortoises and was hooked by the lure of fieldwork. ”It`s a lot more tantalizing than dissection,” he says.
Sereno`s first dinosaur travels were his most extensive. Financed by the museum and The National Geographic Society, he became, in 1984, the first American graduate student in decades to study in China. He bought a ticket to Beijing and a return flight to London and set off with $10,000 in cash tucked into a holster under his vest.
He spent months picking through bones in unheated, dimly lit rooms housing Beijing`s paleontological collections, detailing a vast and largely undescribed collection. In all, he snapped 14,000 slides of his travels and the fossils he encountered.
Sereno had set out with a scientific mission-to reclassify all of the hundreds of bird-hipped dinosaurs, one of the two orders into which these ancient reptiles have long been grouped. In his four months at the Beijing laboratories, Sereno made significant progress. He pegged two then-
unidentified specimens as new species of parrot-beaked dinosaurs, browsers up to 8 feet long that played a central role in the ancestry of the horned dinosaurs, such as Triceratops, of the American West.
It took Sereno four months to reach London; in that time he logged 12,000 miles via Mongolia, Soviet Siberia and Europe. Through sheer persistence, he became the first American scientist in nearly half a century to visit the spectacular orange-hued Flaming Cliffs of Outer Mongolia, where the first dinosaur eggs were discovered.
Eight months after he`d left, Sereno was back in the U.S., with all the accomplishments of Phineas Fogg, regaling envious colleagues with the first of his spectacular slide shows. He also incorporated his studies of Asian dinosaurs into the new cladistic perspective on bird-hipped dinosaurs, which he first presented at a German conference in 1984. (Cladistics is a system for plotting the relationships of animals according to their significant similarities. Decades old, it was nonetheless resisted by paleontologists until Sereno and several colleagues began remaking dinosaur studies in the 1980s.)
Through cladistics, Sereno determined a likely candidate for the most primitive bird-hipped dinosaur (from South Africa) and a pattern of relationship for all other members of the group, from duckbills to stegosaurs, in effect, from dome-headed battering rams to armored tanks. ”It was a sweeping, solid piece of work,”says the University of Pennsylvania`s Dodson, ”and all the more convincing for all the specimens Paul had examined.”
After the other half of the dinosaur world, the lizard-hipped line, was reorganized by scientist Jacques Gauthier, one great dinosaur-evolution mystery remained for Sereno: What and where were the earliest dinosaurs, those that evolved before the split between the bird-hips and the lizard-hips?
To Sereno, Argentina seemed the logical place to look. Fragments of some of the oldest dinosaurs known, nearly 235 million years old, had emerged during decades of sporadic digging in Argentina and neighboring Brazil. Some Argentine fossil discoveries had come at great cost. In the early 1960s Harvard University researchers ran afoul of local police and, according to one worker, spirited away a crate of fossils while being chased by gun-toting officers; other fossil treasures were impounded in an Argentine jail.
But regional conflicts had diminished greatly by the time Sereno went to Argentina, and he enjoyed a working relationship with the country`s dinosaur guru, Jose Bonaparte, of Museo de Ciencias Naturales of Buenos Aires. On a modest budget, Sereno, Bonaparte and eight associates set out for the badlands of northwestern Argentina, two hours` drive from the nearest town. Sereno and Bonaparte had found their field vehicle, lacking an engine, in a repair shop. Midway into their six-week venture, the gas line and pump failed. A talented Argentine mechanic kept the vehicle running, but a crew member had to sit on the roof with a gas can on his lap to keep the vehicle operating at full power.
In the foothills of the Andes, they came to an enormous, barren depression, running north to south and strewn with sandstone towers, mesas and rust-red lumps of ironstone-land known on tourist maps as the Valle de la Luna (Moon Valley). In its midst was a provincial park, a refuge for guanacos, rheas and armadillos. Bordering the valley to the east was a wall of cliffs.
To Sereno, it was the most remarkable terrain he had ever seen-snow-capped mountains in the distance and, around him, shapes and colors to
”equal the Painted Desert” of the American West ”and escarpments that made the Flaming Cliffs of Mongolia look like mere ridges.” The group promptly found fossils galore. Sereno stayed for several weeks, during which he helped excavate remains of more than 100 animals-primitive dinosaurs plus a host of their contemporaries.
One morning in the third week of their dig, Sereno insisted on visiting a corner of the basin that the group appeared to have missed in its early prospecting. He recalls ”gazing at this little back valley at lunch from a lookout ridge and musing that it was there that a whole early dinosaur lurked.” After spending the morning of a day off taking photos of the field camp, he decided to follow his hunch.
After the long drive and hike, Sereno descended into the badlands. ”I laid my pack on a prominent rocky spine and walked off 50 feet, straight to a mound of bone. At first I thought it might be just another bloody rhynchosaur,” a cowlike contemporary of early dinosaurs. ”Then my eyes slowly stopped along what appeared to be neck vertebrae-literally, one by one- right up to the back end of the skull of a primitive dinosaur.”
What Sereno had found, he knew instantly, was far and away the most complete remains of an early dinosaur ever discovered. The narrow top of the foot-long skull lay exposed, still linked to the neck and part of one arm, on a sandstone knob, bathed in red iron-bearing mineral. The fossil was elegantly preserved, locked into place by sand grains that had washed out of rivers to surround the bones when the land was well irrigated, some 230 million years ago.
The sober academic recounts that he ”literally went crazy, yelling. The crew slowly trickled in, amazed at the sight. When they heard my yells, they either thought I had found just what I`d found or that someone had died.”
Sereno returned to the skeleton, after pacing a distance, and wept. ”It was such a beautiful skull. Our search was over. We`d done it!”
The skull proved to be so well-preserved that tiny bones around the iris of its eye were still intact. The dinosaur to which the skull belonged was Herrerasaurus, a primitive predator up to 15 feet long, with slender, flexible jaws.
When Sereno first showed slides of this find, at the 1988 convention of North American paleontologists, in Alberta, Canada, the sight of the skull brought gasps. The details of the skull`s architecture were published in December in a paleontological journal, along with Sereno`s extensive insights into the structure of primitive dinosaurs. A life-sized Herrerasaurus by ace dinosaur sculptor Stephen Czerkas will likely grace the Field Museum`s life history halls when they reopen in 1994.
Sereno doesn`t consider his work at Valle de la Luna finished. He returned last fall to search the underlying sediments, some five to 15 million years older than those around the dinosaur skull. His goal was to find more transitional animals, the missing links between dinosaurs and their reptilian ancestors, to better date the fossils he had found and to understand the ancient environment. As always, Sereno got results, findings he will unveil later this year at a press conference arranged by The National Geographic Society.
In 1990 another great find fell into Sereno`s lap. Rao Cheng-gang, a Chinese colleague, brought him a small fossil skeleton found by a child in northeastern China. The delicate fossil was isolated at the Field Museum by acid baths, which slowly etched away its matrix. What remained was a sparrow- sized bird, newly named Sinornis, that dated to the middle of dinosaur days, nearly 135 million years old. Sereno determined that with its strikingly modern wing and a perching foot intact, this was clearly the oldest known bird capable of sustained flight. The famous Archaeopteryx is 10 million years older but, with its long tail and weak chest, lacked the strength and aerodynamics for flying distances.
Sereno unveiled Sinornis at the 1990 convention of the Society of Vertebrate Paleontology, in Lawrence, Kan., and once again his colleagues were impressed. Says Dodson: ”Paul can always be counted on for an astounding discovery. It`s getting to be an annual feature of the SVP program.”
The fall 1992 convention, in Toronto, will undoubtedly feature Sereno`s professional videotape of his most recent expedition, to the virgin fossil fields of Niger, Africa. Sereno spent six weeks this past winter teamed with British Museum researchers David Ward and Peter Forey, among others. Ward had been with a larger team four years before and found huge pieces of brontosaur- like dinosaurs in the Sahara, following in the tracks of French explorers four decades before.
This time, Sereno used his own vehicle for what was intended to be a follow-up survey. The team met in London, then proceeded through Europe and North Africa by car and ferry, slogging the last several hundred miles through the Sahara over ancient caravan routes. There were many instances when Sereno swerved at the last moment to avert sinkholes that would have marooned their vehicles hundreds of miles from the nearest oasis.
The team found several promising sites, including one that was dated close to the end of dinosaur presence. But it was a chance stop at the village of a local chieftain that led them to their richest discovery. The chief had a dinosaur bone on his table and happily offered to lead Sereno to many more.
What followed was a winding journey of several hours, during which the caravan and its guide lost their way several times. At one point, Sereno stopped in frustration while the guide continued in another vehicle. ”Within a half-hour they were back,” he recalls, ”yelling that they`d found it.”
”It,” Sereno says, was a vast graveyard of giant dinosaurs, a plain of mound after mound of only slightly jumbled behemoth bones. ”Each pile seemed to belong to a different dinosaur. It was really bizarre,” he says. From the soft dirt, Sereno was able to exhume a femur, a leg bone longer and wider than his nearly 6-foot frame. Chopped in six sections, it was transported to London, where it now sits in Ward`s study, awaiting the rest of its more than 70-foot-long frame.
This dinosaur and its companions, including large meat-eaters that shed their teeth in an apparent feeding frenzy on the giant corpses, are relics of an evolutionary period only dimly understood. At the dawn of the last dinosaur period, more than 110 million years ago, Africa and South America were breaking apart as the Earth began dividing into modern continental
configurations. Dinosaurs that had passed freely between the land masses were now relegated to isolation, left to evolve in their own curious directions.
From this time comes tantalizing fragmentary evidence of sail-finned hunters, including Spinosaurus, possibly more than 50 feet long, making it the largest predator ever to walk the earth. And North Africa produced fossils of some of the most primitive of the duckbilled dinosaurs that were to proliferate several million years later in the Northern Hemisphere. The spoon- shaped teeth of the giant browsers Sereno uncovered appear to be like no other of these giants and may provide further evidence of a peculiar African fauna.
Sereno`s legs twitch with energy as he describes the spot: ”Africa is the last great unexplored territory for dinosaurs.” Not for long, however. Sereno has a hard-won invitation from Niger authorities to return this September for three months, accompanied by a public-television crew, and he plans to alternate fall missions to Africa with others to Argentina for several years to come.
Meanwhile, Sereno sits uneasily in his neat, if crowded, fourth-floor office in a drab Organismic Biology and Anatomy building at the University of Chicago. Press clippings, sumptuous photographs of wild and distant valleys and letters from grateful schoolchildren Sereno has entertained adorn the hallway bulletin boards. Around him, Sereno`s file cabinets are overflowing with manuscripts and illustrations for papers he is writing. ”I won`t be going anywhere for a while,” he says wistfully. A moment later, he reconsiders. ”I have been invited to do some work in China by my friends there.”
If he goes, it`s a good bet he`ll come back with something special. For all his thorough planning, discovering new dinosaurs is a good fortune not lost on Sereno. He says, ”I`ve been so lucky, it must mean I`ll die young.” But content.
