Dinosaur Country

First published in Alaska Magazine, April 2012. All rights reserved.

(No, I don't know why it formatted this way. Probably because I am a technological MARVEL.)

By Barb Cooper

Alaska’s North Slope is the epitome of unwelcoming terrain. From the Brooks Range northward to the coastline, the coastal tundra has a harsh, bitterly cold climate, and lies on top of a permanently frozen soil called permafrost. It is remote and forbidding; inhospitable and potentially deadly.

But 75 million years ago, during the Late Cretaceous Period, Alaska was a very different place. Mountain ranges were just beginning to form and there was a bridge of land across what is today the Bering Strait. It was warmer; plant fossils and other indicators show that the climate was similar to that of southern Canada or the northern edge of the Lower-48 states. Even the stars that shone over Alaska
were different. And the animals were different, as well.

Alaska isn’t the first place most of us think about when we think of dinosaur fossil hunting but, the truth is, large herds of dinosaurs lived here in a complex ecosystem that scientists are only now beginning to understand. Recent discoveries of the fossilized bones and tracks of dinosaurs in the northern part of the state have been significant, and are challenging everything scientists thought they knew about how dinosaurs lived and died millions of years ago.

And for paleontologist Tony Fiorillo, chief curator and director of research for the Museum of Nature and Science in Dallas, Texas, the state’s North Slope, even with the extreme climate found there today, is one of the most exciting places on earth. In fact, he says the entire state of Alaska is a “great big paleontological candy store.”

Compared to elsewhere in the world, the discovery of dinosaurs in Alaska is fairly recent. In 1961, a geologist for Shell Oil Company named Robert L. Liscomb found a handful of bones of a duck-billed dinosaur, Edmontosaurus, on the banks of the Colville River. These bones were extremely well-preserved, and Liscomb sent them back to his office, intending to have them studied by a paleontologist. Unfortunately, Liscomb died the next year in a rockslide, so they were in a Shell warehouse until about the mid-1980s, when Shell was cleaning house, and they sent the bones to the United States Geological Survey. There, they were brought to the attention of paleontologist Charles Repenning, who immediately recognized that they were dinosaur bones. In the late 1980s, the University of California Museum of Paleontology and the University of Alaska Museum headed back to the Colville River site, which came to be called the Liscomb Bed, turning up finds that hinted at the abundant remains of dinosaurs and other animals.

Fiorillo’s interest in northern high-latitude dinosaur ecosystems led him to Alaska in 1998, and he has made research trips to Alaska every year since, most recently expanding the search into several of the state’s national parks. Today, he is one of the world’s leading paleontologists working on polar dinosaurs. And that group of dinosaurs is proving significant in the paleontological world.

“Finding polar dinosaurs was important because it provided whole new insights into the biology of dinosaurs,” said Hans-Dieter Sues, senior scientist and curator of vertebrate paleontology at the Smithsonian Institution. “The traditional view was that dinosaurs were all overgrown reptiles that lived under tropical conditions. When we found polar dinosaurs, however, it was driven home to everyone that dinosaurs could live and thrive under different climate conditions,”

Fiorillo and his colleagues are focusing primarily on two areas of Alaska: the North Slope and Denali National Park. On the North Slope, the scientists have found a huge number of dinosaur bone fossils, leading them to conclude that it might have been a “seasonal killing field.” The dense concentration of the bones and fine river sediment suggests the dinosaurs were caught in a flash flood and swept to their deaths.

“Given the unique geography of high mountains next to a warm coastal plain in a polar world, there was a greater probability of getting clocked by a flood than places farther south,” Fiorillo said.

Most of the dinosaurs appear to be juveniles, which further supports the idea of a flood or unexpected runoff. The scientists theorize that the taller, more able, adult dinosaurs might have been able to cross the flood channels.

In Denali National Park, Fiorillo and his team have found thousands of tracks made by dinosaurs and prehistoric birds. “The North Slope bones tell us who was at the party and  Denali tells us what the dance was,” he said.

The “dance” includes unprecedented information about the full polar ecosystem. In addition to prehistoric bird tracks and plant- and meat-eating dinosaur tracks, there is a wealth of trace fossils including fish, worms and crayfish. All of this points to significant biodiversity during the Late Cretaceous Period.

“It’s all here,” Fiorillo said. “It is just phenomenal.”

Of course, finding dinosaur bones in Alaska, especially on the North Slope, is not as easy as Fiorillo makes it sound. Researchers travel by helicopter and boat as far as possible, and then begin scaling near-vertical cliffs to reach their destinations. In addition to the inherent challenge of access, the teams must work within the structure of a short digging season, wrestling with unpredictable weather patterns, braving hostile wildlife and a host of other challenges. All supplies must be packed in, and then there’s the issue of how to safely remove enormous, fossilized bones.

“You rely on the people you’re with to problem-solve,” said Fiorillo. “On the days when you’re cold and wet because of uncooperative weather—or when you haven’t taken a shower in three weeks—you can’t help but laugh at the misperception of how this job is so glamorous.”

The effort is well worth it. Perhaps the most exciting discoveries to date by Fiorillo and his team are the new species: two prehistoric birds and an enormous dinosaur named Pachyrhinosaurus perotorum. In 2006, during an exploratory dig near the Colville River, the team excavated a deposit of hundreds of bones, including some partial skulls, from at least 10 individuals, of a horned dinosaur, Pachyrhinosaurus (a rare relative of the better known Triceratops.) As luck would have it, the extraordinary find was recorded by a crew from the PBS television show NOVA, which later made an hour-long documentary about the expedition titled Arctic Dinosaurs. (Chris Schmidt, co-producer and writer of the show, described the filming as “one of the most uncomfortable and hair-raising experiences of my life.”)

Once the dig was completed, Fiorillo and his team methodically packaged the precious cargo in plaster-burlap jackets (although getting plaster to harden in sub-zero temperatures proved challenging), and then painstakingly airlifted them by helicopter to the nearest airstrip. They were flown to Fairbanks, placed in wooden crates and marked “Dallas or bust,” and transported to Dallas by truck.

It took nearly four years of meticulous cleaning and reassembly by Fiorillo and his colleague, Ron Tykoski, at the Museum of Nature and Science, before the scientists knew they had found a new species.

“It’s as if someone took 15 pachyrhinosaurs, dumped them into a blender for 30 seconds, poured all the mess out into a ball of concrete, then let it solidify for 70 million years,” said Tykoski, chief fossil preparator at the museum.

Fiorillo remembers the work fondly. “Discovering hundreds of bones from all of these pachyrhinosaurs in one spot was unbelievably exciting, and we really thought the expedition was an incredible success. To later realize that we had unearthed a whole new species was one of the best days of my career,” said Fiorillo.

Fiorillo and Tykoski named the new dinosaur Pachyrhinosaurus perotorum after the H. Ross Perot family, benefactors of the museum. The species is distinguished by a radically different placement of its horns and, while it is similar to two other thick-nosed species paleontologists have found, one in southern Canada and one in northern Alberta, the Alaska version has subtle differences and is the youngest of the three by a few million years.

The two new prehistoric bird species were discovered in Denali National Park from fossilized bird tracks dating back 70 million years. One track was very large—so big that the scientists estimate the bird that made it stood about five feet tall, or almost one-third larger than a Sandhill Crane. Fiorillo and his team named it Magnoavipes denaliensis, using the Koyukon Athabascan name for the region and paying homage both to Denali National Park and the tallest mountain in North America. The second, smaller bird, Gruipeda vegrandiunis (which translates roughly to “tiny one,”) was about the size of a modern sandpiper.

Two important conclusions can be drawn from the discoveries of these new species, explained Fiorillo. “First, some 70 million years ago Denali National Park had remarkable bird biodiversity. Rocks there record the richest record of avian biodiversity from a single rock unit anywhere in the world,” he said. “And, second, the fact that some of the forms of bird tracks we found in Alaska are also found elsewhere in the U.S. and Asia suggests that birds used Alaska as a seasonal nesting ground some 70 million years ago, just like modern birds use Alaska today.”

In addition to the new species discovered, Fiorillo’s team also found pterosaur handprints Denali National Park in 2008, the first record of this group of flying vertebrates in Alaska. Pterosaurs were large winged creatures (some had wingspans of 25 to 30 feet) that were closely related to both crocodiles and dinosaurs. Until 2008, there had never been evidence of their presence as far north as Alaska. Better pterosaur specimens have been found with hair-like structures preserved with the skeletons, leading paleontologists to speculate that having a furry covering must have meant that pterosaurs were warm blooded (endothermic) like birds and mammals. Being found in a place where known cold-blooded animals are absent—no fossils of crocodiles or turtles from the late Cretaceous have been found in Alaska—supports the notion that pterosaurs were endothermic.

During the Cretaceous Period, the most common dinosaur was a duck-billed plant-eater named hadrosaur. Hadrosaurs were so common, in fact, that many paleontologists refer to them as the “cows” of the Cretaceous. There are thousands of tracks of hadrosaurs in Denali National Park and hadrosaur bones have been found on the North Slope, as well. And, while these dinosaurs are not unique to the state, their discovery here has offered rare insight into how they lived together some 70 million years ago. Scientists now think that hadrosaurs were gregarious, displaying different levels of sociability at different points in their lives. The footprints in Denali suggest that, for at least part of their lives, hadrosaurs lived in family units, with adults caring for babies and juveniles.

So, what happened to the Polar Dinosaurs? One prevailing theory is that an asteroid slammed into the Earth near the Yucatan Peninsula and killed off about 50 pecent of life on the planet, and resulting fires and dust clouds killed almost everything else. Fiorillo doesn’t buy into that model, though, because of fossil proof that birds and mammals survived.

“One could argue that mammals, being very small at the time crawled under rocks and waited for life to get better,” he said. “But what do birds do? They fly. How did they survive such a catastrophe?”

Fiorillo thinks a better explanation for the extinction of the dinosaurs is that the climate changed and some organisms adapted and others did not, much as we see animals in our modern age struggle to adapt or risk extinction.

In a world moving as fast as this one, far removed from the times when these ancient creatures roamed the earth, why are we still so fascinated with how dinosaurs lived and died? Fiorillo thinks the study of dinosaurs opens a broader discussion about life today. Rather than “the fossils we are finding as merely a glorified exercise in stamp collecting, I think what our work has shown is that during the Cretaceous, the ancient Arctic was an area with a rich, warmer terrestrial ecosystem,” he said. “And as a result of that, in addition to questions about biodiversity through time, we can begin to ask meaningful questions about what a warm Arctic may mean to a society currently concerned with global warming.”

Addressing the challenges of global warming by looking to our ancient past is a big part of answering the question of why we study dinosaurs, and why Alaska is so important in the search for clues to how they lived and died. But there are larger reasons. “There is one history of past life on the planet—the fossil record— and in order to understand the world today we need to know how we got here,” said Fiorillo. By understanding as much as we can about the lives of dinosaurs, perhaps we gain an understanding of our own place in history.

Plus, they could just be the coolest things ever.


Sarah Tan said…
This is really very interesting. My son really loves dinosaurs, and I can share with him about polar dinosaurs.
Just found this - I'd never heard of polar dinosaurs before! I hope you got a trip to Alaska out of the assignment, but I suspect you were limited to interviews and research. You make a technical topic very interesting and easy for the layperson to understand - thanks!