A retired geology professor was waiting for a boat to pick him up from a riverbank on the North Slope in July 2001 when he saw something unexpected. Bones -- big bones. "Just in those fleeting moments before leaving, I looked down at my feet," said Don Triplehorn of the University of Alaska Fairbanks, who was southwest of Wainwright at the time. "I looked around and probably in a matter of minutes I picked up four bones."
The bones were identified as belonging to ornithopod dinosaurs, a group of plant-eaters whose members include the duck-billed herds like those seen in "Jurassic Park" and date back about 95 million years. It was the farthest west that dinosaur bones have been found in northern Alaska. </STORYBODY>
This July, Triplehorn returned to the area with Dallas Museum of Natural History curator Anthony Fiorillo to look for more. The expedition found only a few bone fragments but discovered a series of dinosaur tracks a few miles upriver, captured in 95 million-year-old mud.
"We don't know a heck of a lot of dinosaurs from North America from 95 million years ago," said Fiorillo, who led the three-man expedition.
Fiorillo said the bone and track findings at these two sites fill a chapter in geography and time in Alaska's paleontology.
They are not the oldest dinosaur fossils found here; two that date 145 million to 150 million years back to the Jurassic period have been found on the Alaska Peninsula and in Katmai. But they are significantly older than the 70 million-year-old bones Fiorillo has been excavating on the Colville River on the North Slope.
"There's so little done in vertebrate paleontology in the Arctic, especially in the United States Arctic, that every time we go out we find something new," said Roland Gangloff, interim curator of earth science at the University of Alaska Museum of the North, in Fairbanks.
The trackways, or a sequence of steps, that Fiorillo found in July belonged to three kinds of dinosaurs -- an ornithopod, a 20-to-25 foot theropod, or mostly carnivorous dinosaur, and a smaller 6-to-8 foot theropod.
"Psychologically, they came at a great time," Fiorillo said. "We weren't finding bones. The depression wasn't setting in just yet, but you could see the faces were getting a little long. And then lo and behold."
Trackways are one of many kinds of fossil evidence of dinosaurs that have been found in Alaska. Individual tracks, impressions of skin, teeth and bones, bite marks on bone, natural molds of bodies, and amber are all other fossils that paleontologists use to help understand when, where and what kinds of animals lived here.
Triplehorn said the tracks were left in "some kind of mud flat that these creatures walked across while it was still damp." To remain after millions of years, the material must be "soft enough to take the impression, but not so soupy that it just goes 'slurp.' "
Ninety-five million years ago, when dinosaurs still had another 30 million years on Earth, that part of Alaska was probably a conifer forest, with a lush undergrowth of plants. Fiorillo also collected fossils in the area of conifers and leaves, some of which suggested evidence of a forest fire.
"A 95 million-year-old forest fire," he said.
The dinosaur fossil sites on the Colville River, where Fiorillo has returned to work every summer since 1998, have been a rich source of bone fossils. But up until Triplehorn's serendipitous discovery, bones had only been found as far west as Umiat.
The new site's western location may ultimately be significant as a way to learn more about Beringia, the region surrounding the land bridge that connected North America and Asia.
The bridge, approximately tracing the continental shelf of the Pacific Ocean, could have been hundreds of miles wide, from north of Barrow to the Pribilof Islands.
It is traditionally believed to have been crossable at points during the past 2 million years, according to retired scientist Dave Norton, who taught in Barrow and at UAF.
Fossils found in Alaska of dinosaurs otherwise concentrated in Asia might indicate the land bridge was present much earlier. Dinosaurs became extinct around 65 million years ago.
"These are pretty good indicators that the forms of life that were dominant a very long time ago were able to waltz back and forth between Alaska and Russia," Norton said.
Western Alaska is crucial to this theory because dinosaurs would have appeared there before making their way east.
"Anything in this area could lead to critical information," Gangloff said.
In terms of staging excavations, it's also tricky.
This expedition had a short window of good weather to travel the 30-40 miles from Wainwright through the Wainwright Inlet down the Kuk River to the sites on the Kaolak River. Storms regularly bombard the area, and until June, rivers are clogged with ice.
A Wainwright guide, Ben Ahmaogak Sr., helped with boats and navigation up rivers, which can be very shallow.
"You end up getting out with a rope over your shoulder and dragging the boat upstream," Triplehorn said.
Because large parts of Alaska were not covered by ice-age glaciers, the state has proven to be a hotbed of dinosaur fossils since regular excavations began here in the 1980s. High-latitude fossils are not as common in parts of Asia and Canada that were gouged and hammered by ice sheets, Norton said.
The finds from the two new sites in the Nanushuk rock formation will eventually join the collection of the University of Alaska Museum of the North.
"It's fun just to watch it," Norton said. "It seems like every year people are just astonished all over again that there were dinosaurs in Alaska. It's never going to wear out."
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