From marine reptiles that swam in the Arctic seas to duck-billed dinosaurs that thrived in polar forests, Alaska’s fossil record paints a vivid picture of life at high latitudes during deep time.
Alaska’s geological history is a complex collage of terranes—fragmented pieces of crust that accreted onto the North American plate. This makes the state an exceptionally diverse fossil site, with deposits spanning from the Paleozoic to the Cenozoic.
Some of the most significant fossil discoveries in Alaska come from:
- Prince Creek Formation (Late Cretaceous): One of the northernmost dinosaur-bearing formations on Earth, located along Alaska’s North Slope.
- Liscomb Bonebed: A hotspot for Arctic dinosaurs, discovered in the 1960s and later explored in detail by Kirk Johnson and colleagues.
- Tuxedni Group (Jurassic): Marine invertebrates, including ammonites and bivalves, are common here.
- Chickaloon Formation (Paleocene): Known for its beautifully preserved fossil plants, including fossilized redwoods and Metasequoia.
One of the most astonishing aspects of Alaskan fossils is the presence of polar dinosaurs. During the Late Cretaceous, the Arctic Circle was a much warmer place than it is today, but still experienced months of darkness.
Herbivorous dinosaurs such as Edmontosaurus, Ugrunaaluk kuukpikensis (a newly named hadrosaur species from the North Slope), and Pachyrhinosaurus lived in herds in this high-latitude environment, while predators like Nanuqsaurus hoglundi, a smaller relative of T. rex, prowled the dark forests.
These animals were uniquely adapted to life in extreme conditions. Evidence from bone histology suggests that these dinosaurs had growth cycles influenced by the harsh Arctic climate—some may have hibernated or experienced slowed metabolism during the winter months.
Kirk Johnson’s research, alongside collaborators such as Tony Fiorillo and Roland Gangloff, has been central in understanding how these polar ecosystems worked. Johnson has led expeditions into the Arctic wilderness, collecting fossils and reconstructing ancient environments based on plant fossils, sedimentology, and isotope analysis.
Fossil Plants and Climate Clues
While dinosaurs grab the headlines, the fossilized flora of Alaska is equally important. Johnson is particularly renowned for his work on fossil plants, which he has used to reconstruct past climates and landscapes. In the Chickaloon Formation, for instance, fossilized leaves, cones, and wood fragments tell the story of an ancient rainforest-like environment that thrived just after the age of dinosaurs, during the Paleocene.
A paper of interest he co-authored with Dr. David J. Nichols—a distinguished paleobotanist and palynologist with the U.S. Geological Survey whose research significantly advanced the understanding of fossil pollen, spores, and Cretaceous-Tertiary boundary events.
Over his career, Nichols became known for his expertise in using fossilized plant micro remains—such as pollen grains and spores—to reconstruct ancient ecosystems and trace climatic and environmental shifts through geologic time.
His collaboration with Dr. Kirk Johnson on the Prince Creek Formation in northern Alaska combined his palynological skills with Johnson’s macrofossil plant research, providing a comprehensive view of Late Cretaceous polar flora and their ecological significance.
Nichols’ meticulous work helped illuminate how vegetation patterns responded to ancient climate change and extinction events, making his contributions invaluable to studies of high-latitude paleoecology and Earth system history.
- Johnson, K. R., & Nichols, D. J. (2008). Plant fossils from the Prince Creek Formation, North Slope, Alaska: Implications for Late Cretaceous polar ecosystems. In: "Studies on Fossils in Arctic Environments." Geological Society of America Special Paper 442, pp. 155–170. DOI:10.1130/2008.442(10)
This paper documents high-latitude Cretaceous flora, revealing that Alaska once supported lush forests, with taxa such as Metasequoia (dawn redwood), ferns, and angiosperms flourishing under a warm polar regime. These fossils help scientists understand long-term climate dynamics and serve as analogs for future warming scenarios.
Marine Reptiles and Cretaceous Oceans
In southern Alaska, Jurassic and Cretaceous marine sediments have yielded remains of ichthyosaurs, plesiosaurs, and large ammonites. These fossils suggest that Alaska’s ancient seas were home to thriving marine ecosystems. Fossil localities near the Talkeetna Mountains and along the southern coast contain rich assemblages of mollusks and marine reptiles, providing a window into life in northern marine ecosystems during the Mesozoic.
The Role of Citizen Science and Indigenous Knowledge
Much of Alaska’s fossil record has been unearthed through the combined efforts of scientists, local fossil hunters, and Indigenous knowledge holders. Collaborative research involving Native Alaskan communities, especially in regions like the North Slope, has been critical in facilitating fieldwork, protecting fossil sites, and sharing discoveries with local schools and museums.
Kirk Johnson: Bringing Alaska's Fossils to the Public
Kirk Johnson’s contributions extend beyond fieldwork. He is known for making paleontology accessible and engaging to the public. He co-authored Cruisin’ the Fossil Freeway with artist Ray Troll, a visually wild and informative tour of North American paleontology, including Alaskan fossil stops. Johnson has also hosted PBS documentaries like Making North America, in which Alaskan geology and fossils play a key role.
To get your copy of Cruisin' the Fossil Freeway, here is the link: https://www.amazon.ca/Cruisin-Fossil-Freeway-Kirk-Johnson/dp/1555914519
Additional publications by Johnson and his work in Alaska include:
Johnson, K. R. (2002). A North American perspective on the Cretaceous-Tertiary boundary in terrestrial settings. Geological Society of America Special Paper 361.
Fiorillo, A. R., & Gangloff, R. A., & Johnson, K. R. (2000). The role of polar dinosaurs in Mesozoic ecosystems: A synthesis. Journal of Vertebrate Paleontology, 20(3), 34A.
Alaska’s fossil record is one of the most compelling in the world, telling stories of survival and adaptation in the face of darkness, isolation, and dramatic climatic shifts.
Whether it’s a duck-billed dinosaur enduring polar nights or a fossil leaf bearing witness to ancient greenhouse climates, each discovery contributes to our evolving understanding of Earth’s history. Thanks to scientists like Kirk Johnson and their ongoing efforts, we can explore these icy time capsules and better appreciate the deep-time legacy of the Last Frontier.
