Over the course of a long June day, when the glow of sunshine never fully leaves the Alaskan sky, National Park Service scientist Cassi Knight strides over alpine tundra and bushwhacks through alder and willow thickets under the shadow of Denali. The park is known for its namesake peak and charismatic megafauna, but Knight, 27, isn’t particularly interested in those at the moment. She’s staring through her binoculars, gazing across the hills and huge valleys for something few people know exist in Denali National Park and Preserve: fossils.
There, over the past 11 years, paleontologists have discovered a trove of more than 300 fossil sites preserving 70-million-year-old dinosaur tracks, bird tracks, and plants of all kinds, including enormous sequoia-like trees and ancient sinewy horsetails. The fossil record is so extensive that paleontologists have been able to piece together a complete view of the ecosystem here in the late Cretaceous period (100 to 66 million years ago). In a Pacific Northwest-like climate, huge duck-billed plant-eating dinosaurs and two-legged predators roamed, birds similar to sparrows and herons patrolled the sky, and lush ferns crowded the understories of skyscraping forests.
Because fossils were so recently discovered in Denali, many questions remain, such as how the plants and animals adapted to the cycles of 24-hour daylight and 24-hour darkness. Perhaps the biggest question, however, is what fossils and tracks still remain uncovered—and it’s Knight’s job is to answer that.
“It’s a huge challenge to figure out what’s out there just because of the nature of this place,” says Knight, who has encountered more bears than she can count, hiked through raging rainstorms, and endured summer temperatures near freezing. “But having that sort of unknown out in the park, it allows you to make new discoveries all the time, and that really speaks to me.”
The fossilized tracks and organic remains largely lie in rock known as the Cantwell Formation. While park scientists aren’t allowed to do excavations in wilderness areas, they can let the earth do the excavations for them. Luckily, in Denali, there are plenty of landslides. Knight typically sleuths Google Earth for outcroppings or fresh landslides, then, with a co-worker, shoulders her backpack and treks out into the wilderness for one or more days of hiking. Recently, while on a four-day backcountry expedition, she and geology intern Tyler Hunt discovered a rocky surface with 15 dinosaur tracks, each approximately 18 inches wide.
“I don’t think I’ve ever really had a job like this where things were just so open and almost every time that I go out, a new site is found,” says Knight. “You get to be the first person to see stuff in 70 million years—or really ever, because there were no people 70 million years ago.”
Knight is also tasked with monitoring known fossil sites to make sure they haven’t been damaged by erosion, earthquakes, landslides, or visitors. So far, only one of the fossil sites, known as Dino Dance Floor—a collection of hadrosaur and T. rex-like theropod tracks, as well as horsetail and metasequoia fossils—is regularly visited. So far, there hasn’t been any damage or vandalism, which have been common in other parks. But still, questions remain.
“One of the crazy things here that people are still trying to wrap their heads around is, we have all these dinosaur tracks, bird tracks, and plant fossils in the Cantwell Formation, but why in the world have we never found dinosaur bones here?” says Knight. “That’s something we’re constantly grappling with.”
It’s possible that conditions weren’t favorable for preserving skeletons 70 million years ago. Another explanation is that they’re out there, but the park is vast, summer is short, and the bones simply haven’t been discovered—yet.
Desired Superpower: “I’d love to be able to speak every language in the world because you could learn so much from so many people and gain so many different perspectives!”
Essential Field Item: “Binoculars. They come in handy for finding fossils from a distance. And they’re great for the game called Bear or Rock, where you’re trying to figure out if a distant dark spot is a bear or a rock.”