November 10, 2008
When I think of places to look for dinosaur bones, the badlands of the western United States and the desolate Gobi desert most immediately come to mind. I would never have guessed that Alaska, of all places, would hold a treasure trove of dinosaur bones, yet there they are. North of the Arctic Circle, on Alaska’s North Slope, lie the scattered remains of dinosaurs like the horned Pachyrhinosaurus, the tyrannosaur Gorgosaurus, the hadrosaur Edmontosaurus, and the maniraptorans Troodon and Dromeosaurus. Smithsonian magazine ran a story about polar dinosaurs last year and now the NOVA documentary “Arctic Dinosaurs” tells the story of their life, death, and discovery.
Seventy million years ago, near the end of the Cretaceous period, Alaska’s North Slope was closer to the North Pole than it is today. This means that it experienced nearly four months of darkness every year instead of the six weeks of night of today. The climate was much more temperate then, however, as indicated by the plants that lived at the time. It would not be an unfamiliar setting if we saw it today. The dinosaurs would have lived in a temperate forest like those seen in southern Alaska today, with ferns covering the ground and tall conifers stretching into the air.
Such was the home of many of the great North American dinosaur lineages at the time, but no one knew that they were there until just a few decades ago. In 1961, an oil geologist working for Shell named Robert Liscomb found a large fossil on the North Slope. He sent it back to a Shell warehouse, but he died in a rockslide the next year and his find fell into obscurity. It was not until Shell decided to do some spring cleaning in the 1980’s that the bone was found, sent to the United States Geological Survey, and identified as belonging to a dinosaur.
The location of Liscomb’s initial find was then tracked down, and the documentary picks up with the present efforts of paleontologists Tom Rich and Kevin May to further excavate the site. Such a task is not easy. The weather is harsh and the site is isolated, and the rock is hard and frozen. Where some fossil sites require only a sharp eye and a popsicle stick, the Liscomb bone bed requires dynamite to even get to the bones. Then it takes a combination of power and finesse to remove them from the rock, particularly after the team returns to the site and finds that the floor of their bone mine became covered with several inches of ice during their absence!
Another team working on the North Slope, led by Anthony Fiorillo, did not have to worry about blasting through rock, but the challenges were no less intense. A tough climb to the site and freezing rain were near constant challenges for them, and the weather conditions made moving fossils treacherous. The standard operating procedure for transporting excavated dinosaur bones involves wrapping them in plaster-soaked-burlap, which then hardens and holds the fossil and surrounding rock together. On the North Slope it is so humid and cold that the encasing material does not dry well, and so moving the fossils out of the quarry and back to the museum has its risks.
Yet the risks have paid off.
Paleontologists now know that the North Slope was home to not just one kind of dinosaur, but a whole ecological assemblage. But how did they survive there? It was warmer there in the past, but the four months of night choked off plant communities every year. Could the dinosaurs have migrated southward to better feeding grounds like modern caribou? Possibly, but it is difficult to determine.
The alternative would be that the dinosaurs remained during those harsh months, but how they would have gotten enough food is left unanswered. If herbivores went into a torpor or hibernation they would have been easy prey for predators. It seems more likely that herds of herbivores struck out to whatever patches of green they could get to, followed by the meat-eating dinosaurs, but this hypothesis has yet to be confirmed or refuted.
The intertwined stories of discoveries and an ancient Alaska are compelling, but the poor-quality cgi dinosaurs mar the quality of the show. The models presented at the beginning of the show, in particular, are a far cry from the beautifully rendered creatures of other shows like Jurassic Fight Club and even 1999’s Walking With Dinosaurs. The fact that Gorgosaurus, a close relative of Tyrannosaurus, is depicted with three equally-long fingers instead of the correct number of two adds insult to injury.
Nevertheless, “Arctic Dinosaurs” provides a fascinating look at paleontology in action, from a chance discovery to excavation and reconstruction of an entire “lost world.”
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