New Fossil Footprints Discovered at John Day Fossil Beds

Using 3D technology, tracks as old as 50 million years old reveal recently unearthed evidence of mammals, birds, lizards, and invertebrates in Oregon

Cracked tan stone with four small cat-like paw prints — Cat-like footprints from the John Day Formation of Oregon.
NPS

Fossilized footprints of prehistoric birds, invertebrates, lizards, and mammals discovered in John Day Fossil Beds National Monument have been revealed for the first time in a study offering a rare glimpse into ancient animal behaviors after the age of the dinosaurs.

Conner Bennett, a fossil track specialist, led a study that used 3D imaging techniques to measure and study four fossil tracks from two rock layers in eastern and central Oregon. The findings were recently reported in the academic journal Paleontologia Electronica. Dr. Nicholas Famoso, paleontology program manager and museum curator at the park, and Dr. Daniel Hembree, professor of Earth, Environmental, and Planetary Sciences at the University of Tennessee in Knoxville, were heavily involved in the research.

Two of the fossilized tracks, found within ancient lakebed sediments, are between 39 to 50 million years old. They provide the first and oldest evidence of birds and lizards at the park. Beak marks and invertebrate trails alongside two small, bird footprints imply the feeding behavior of a shorebird foraging for worms in shallow water.

“This prehistoric behavior from 50 million years ago is still prevalent today in modern shorebirds,” said Bennett. “It’s fascinating. That is an incredibly long time that these animals has exhibited the same behaviors as their ancestors.”

Another set of tracks, featuring clawed and splayed toes, suggests a lizard once dashed along this lakeshore. This rare find is one of the few known reptile tracks from this period in North America, making it an exciting and significant discovery for paleontologists.

The geology of this region in combination with evidence of a shorebird, worms, and lizard indicate a near-shore lakebed environment. This further reinforces the knowledge that central and eastern Oregon had far greater levels of precipitation and humidity, allowing for the sustainability of lakes and their respective ecosystems.

The footprints found within a 29-million-year-old volcanic ash layer reveals the presence of a cat-like predator, while another set of three-toed hoof prints hints of an ancient tapir or rhinoceros. The pawprints resemble Holophoneus, a bobcat-sized, cat-like predator with large saber teeth. Like modern cats, the bones of Holophoneus tell us that their claws were retractable which is why there is a lack of claw marks visible in the footprints.

The other imprint features three rounded prints, likely made by an ancient tapir or rhinoceros. The nature of the tracks makes it difficult to identify the animal that made the tracks. Overall, these tracks provide a missing piece of the puzzle, helping scientists reconstruct the prehistoric ecosystems of Oregon.

While the park is mostly known for its diverse collection of body fossils, such as bones or teeth, these recent findings belong to a different category. Any geological material that captures the activities and behaviors of ancient animals, such as footprints, burrows, and feces, are called “trace fossils.” Bennett said that by creating a 3D model based on thousands of photographs, he was able to identify and describe these trace fossils that have been in the park’s museum since the 1980s.

“These four different types of fossil tracks preserve a wide variety of animals, including those completely different from the many fossil mammals we have already studied extensively at the park,” said Bennett. “The fossil tracks not only help us confirm their existence at this time but informs us of their different behaviors.”

The published study, “Following their footsteps: Report of vertebrate fossil tracks from John Day Fossil Beds National Monument, Oregon, USA” can be found online in Palaeontologia Electronica with the link below: https://doi.org/10.26879/1413