A belemnite fossil embedded in a piece of rock being held by a person
Belemnite is the fossilized rigid internal “guard” from a squid-like creature.

NPS Photo/M. Harrington

Katmai's Fossils

geologic map of Katmai

Fossils & Paleontology

Many researchers journey into Katmai’s distant past to explore the park’s rich natural history through fossils. With a variety of fossilized plants, vertebrates, and invertebrates in the park, Katmai’s landscape tells a story that spans millions of years. Through fossils, the park can understand how the terrain and ecosystem has evolved over time.

a simplified geologic timeline showing the Triassic, Jurassic, Cretacious, and Tertiary Period

How old are Katmai’s fossils?

A significant number of the fossils found across Katmai National Park & Preserve are part of the Naknek Formation, which is 160 – 146 million years old. The Naknek Formation is the largest geologic formation in Katmai, and it is from the late Jurassic Period. A wide variety of fossils have also been identified from other geologic periods, like the Cretaceous, which illustrates just how diverse and extensive Katmai’s natural history is.

There is ongoing research in Katmai to locate, identify, and record fossils. This includes a search for dinosaur tracks, like those found in Aniakchak.

Remember: If you see a fossil in the park, leave it where you found it so other visitors and future researchers can experience and learn about Katmai’s fascinating natural history.


What types of fossils have been found?

The list below details the types of fossils that have been identified at Katmai.

many shell like fossils in a rock
Buchia is a common type of fossilized bivalve, which has a hinged shell (like a clam or mussel).

Photo courtesy of S. Gage


  • Scallops (including Buchia*, Oxytoma*)
  • Clams (including Tancredia*, Pleuromya*, Pholadomya*, Inoceramus**)
  • Oysters (including Ostreid*)


  • Sea Snails (including Cerithium*, Polynices*, Biplica**)


  • Tusk Shells (including Dentalium*)
A coiled ammonite fossil laying on a rocky surface with a camera lens cap next to it for size comparison
Ammonite features a coiled shell. The external shell served as the living chamber for mollusks. The largest specimen have reached 6 feet across.

NPS Photo/M. Harrington


  • Ammonites (including Pleuroceras*, Partschiceras*, Phylloceras*, Pachydiscus**, Hypophylloceras**, Baculites**, Glyptoxoceras**, Didymoceras**, Exiteloceras**, Nostoceras**, Acrioceras***)
  • Belemnites (including Cylindroteuthis*, Acroteuthis***)
  • Nautiloids p


  • Sea Urchins (undetermined spines*)


  • Sea Lillies (including Isocrinus**)


  • Brachiopods (including Discinisca***)


  • Bristle Worms (including Ditrupa*)
  • Arthropods
  • Barnacles*


  • Angiosperm leaf fragmentsk
  • Mineralized wood and wood impressionsk
  • Metasequoia (redwoods)k
  • Equidetites (horsetails)k
  • Alder-like leavesk
  • Willow-like leavesk
  • Probable gymnosperm logk

Trace Fossils

  • Burrowing holesk
  • Ripplesk

* Naknek Formation (Jurassic)

** Kaguyak Formation (Cretaceous)

*** Herendeen Formation (Cretaceous)

p Pedmar Formation (Cretaceous)

k Ketavik Formation (Paleocene to Eocene)

Last updated: October 20, 2021

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