The trek for dinosaurs in Alaska’s Aniakchak National Monument & Preserve

“Did you find one?” Tony Fiorillo yelled to his colleague, Yoshitsugu Kobayashi. The two paleontologists were climbing over dumpster-sized sandstone boulders, scanning the long, rocky beach of Aniakchak National Monument & Preserve at low tide for dinosaur footprints.

“I think so,” Kobayashi called back. They have been coming to one of Alaska’s most remote coastlines since 2016 to search for evidence of Late Cretaceous era dinosaurs.

Sedimentologist Paul McCarthy is part of the adventure. “I specialize in the mud between the [dinosaur] toes,” McCarthy joked. It’s a quip he once made on a local public radio show. Fiorillo has never let him forget it. “It was one of the few times you were witty,” Fiorillo, an expert on Arctic dinosaurs, said with a laugh. “A guy remembers things like that.”

This was the first official day of fieldwork for the three scientists who spent eight days in July searching for footprints in an effort to reconstruct the dinosaurs’ ecosystem and explain how they survived here for what may have been tens of thousands of years.

“They weren’t just tourists. They were living, breeding, doing things that dinosaurs did to be successful,” said Fiorillo, a senior research fellow at Southern Methodist University in Dallas.

And what they discover could have significance as Alaska grapples with climate change.

“We have argued that looking to the past can help inform where the future might go,” Fiorillo said. “We think that this stuff can help to contribute to our understanding of modeling what warming in a higher latitude environment means now.”


There was no guarantee they would find anything on this trip, but getting here at all seemed nothing short of a miracle.

A geologist who led expeditions in Alaska from 1927 to 1962 nicknamed Aniakchak “the cradle of storms.” The notoriously nasty weather here marooned the three in the hub community of King Salmon for nearly six days before they could fly out to Aniakchak.

“It’s beautiful everywhere, except where you guys wanna go,” Troy Hamon, a National Park Service pilot, said jokingly during a phone call on day three of the weather delay. “I was kind of hoping for better weather this morning,” Fiorillo lamented on day four. A day and a half later, the fog lifted and sheets of rain relented enough so that a small seaplane could make the run to a tiny cabin that sits on a sandy bluff overlooking the deep blue Aniakchak Bay.

The near century-old building, with rusty, gray metal siding, is on the National Historic register and was operated as a salmon cannery in the 1930s. The scientists hunkered down here for yet another day to wait out high winds and sideways rain, further dampening both the landscape and their spirits.

Fiorillo began his search for dinosaurs in Alaska more than 20 years ago, when he received “a modest amount of funding” from the National Park Service to do a basic paleontology survey at Aniakchak.

“It could have come off as a boondoggle to see somebody from Dallas come to Alaska and say, ‘Can I look for dinosaurs here?’ " Fiorillo said. But he was convinced he’d make a discovery. “We always have to wake up in the morning an optimist and got to bed a pessimist,” he said of paleontologists.

On the last day of his first journey here, with a floatplane already in the air to pick him up, Fiorillo found what he’d come for: the cast of a single footprint protruding from some grayish sandstone. The three toes and the telltale notched heel were sure signs that plant-eating, duck-billed dinosaurs, known as hadrosaurs, lived here. The discovery launched Fiorillo’s career.

This month, he and Kobayashi, a paleontology professor at Japan’s Hokkaido University Museum and an expert on dinosaurs in Mongolia, China and Japan, stood over a kitchen-appliance-sized hunk of sandstone, marveling at knobbly, rounded shapes protruding from the boulder’s surface. The chunkier pieces sticking out from the rock were dinosaur toes, obvious signals that more than one hadrosaur set its foot right into this muck before it hardened 70 million years ago.

Eventually, the two agreed that the block holds three definite footprints.

Over the course of the next week, the scholars would not only discover dozens of new dinosaur tracks but also collect samples of fossilized plant material and organic matter.

“I think we have a pretty good handle on what the environment was like,” said McCarthy, chair of the Geosciences Department at the University of Alaska at Fairbanks and an expert on fossil soils, known as paleosols.

At Aniakchak, he is most interested in the gray mudstones and yellowish sandstones stacked on each other like layers of a cake. They stretch for about a mile along the beach and make up what’s known as the Chignik formation. Running through the middle, like thick chocolate ganache, is a dark, reddish-brown band of rocks. McCarthy spent three years mapping these layers. He’s back this year to sample that thicker dark layer of paleosol.

Back at his lab in Fairbanks this fall, McCarthy will test those samples for their geochemical makeup: major elements and stable isotopes. That data will help explain more about what both the climate and environment were like here during the Late Cretaceous, roughly 70 million years ago.

“The rocks are really interesting, but when you put them together with the paleontology, it just kind of makes the story come even more alive so the interest factor goes way up,” McCarthy said.

A few days into the trip, McCarthy used a hammer and chisel to break small chunks of the paleosols away from the outcrop. In the distance, Kobayashi was perched on a giant boulder, bent over a tablet computer, scrolling through entries on a mapping application. At his feet was a round, beachball-sized rock. Every single one of the 112 dinosaur tracks the team has found in Aniakchak is entered into Kobayashi’s tablet. Each entry includes GPS coordinates, photos and accompanying field notes.

“Dinosaurs lived in a harsh environment - in an Arctic environment,” Kobayashi said. He’s exploring the faunal connections between Asia and Alaska. “Hadrosaurs are the most successful plant eating dinosaurs,” he said. Evidence that hadrosaurs ranged from present day Colorado north all the way to Alaska has Kobayashi considering whether the same animals found here are related to those that thrived in Japan and other parts of Asia.

As he looked at the map on his tablet, which holds a half-decade’s worth of field notes, Kobayashi said that walking this beach and looking through the various layers of sediment is like walking straight through the story of the dinosaurs here, from beginning to end.


“Each layer is like a page in a book,” Kobayashi said. And the chapters, Fiorillo said, are uninterrupted. The sediments McCarthy has mapped tell a story similar to what’s playing out on the ground in Aniakchak Bay today.

Every day when the three scientists return from the field to the cabin, they sit around a table or out on the deck and discuss their findings. They all say it’s easy to imagine what this place may have been like millions of years ago. In some places, there are signs that a river ran through here, just like the Aniakchak River that flows into the bay today. Farther down the beach, the sediments hold evidence of an estuary, much like the one that exists now at the mouth of the river. In other areas of this stretch of rocks, there are sediments from an ancient tidal flat that resembles the ones these scientists traverse each day to get out here.

The footprints preserved in the rock come from both juvenile and adult hadrosaurs. In some parts of the outcrop, there are proportionally more adults and vice versa, which may indicate specific habitat preferences based on the age of the animal.

“It’s a kind of cool thing to be able to understand,” Kobayashi said.

There are no trees, but flora and fauna abound here at the base of the Aleutian Range. “Welcome to fantasy island,” Fiorillo had joked as McCarthy disembarked from the seaplane.

Today, hundreds of migratory sea and shorebirds fly the coastline. Countless bears roam the beaches, often hunkering down in the afternoon sun to rummage through piles of rotting, stinking kelp that washes up on the beach. The beach is also the ideal spot for wolves and foxes, which cruise the tide pools, looking for snacks when the seawater has withdrawn.

While more than 90% of the dinosaur tracks here belong to the bipedal duck-billed hadrosaurs, there are also footprints from a tyrannosaur-like theropod as well as an ankylosaur - an armored species with a clubbed tail - and a small shorebird. On this trip, the team also discovered a roughly 9 by 8.6 inch print made by what they believe is magnoavipes, an ancient cranelike bird.

“This place is just heaving with [tracks],” McCarthy said.


“The frequency and density of tracks at this outcrop is truly crazy,” Fiorillo said, “and we don’t know why that is.”

One question that remains on the minds of all three scientists: How did enormous reptiles survive in a region defined by cold? Previous work by Fiorillo - and other paleontologists, as well - show it’s unlikely dinosaurs migrated during warmer seasons. There’s also no evidence that they hibernated. If that were the case, Fiorillo and McCarthy said, they should have noticed the burrow of a multiton, 35-foot long hadrosaur by now.

The entire section of rock shows no signs of catastrophic volcanic activity, either - peculiar for a region that sits in the middle of what’s now the Pacific’s Ring of Fire, an area characterized by volcanic activity and frequent earthquakes.

This also makes it difficult for the team to pin down specific dates for the story they’re developing to explain how dinosaurs were able to thrive here for so long. Layers of ash, known as bentonites, can help fine tune the dating process, but none exist among the cakelike layers of sediment here.

It was much warmer at the time of the dinosaurs than it is now - similar to present-day Seattle. McCarthy said it may have snowed here, “but it probably didn’t stick.” Fossil plants from a metasequoia - an ancient coniferous tree, similar to the giant redwoods that grow in California today - indicate giant trees lined these beaches. Fossils from the plants can be found in the rocks.

This year’s field season also turned up a giant fossilized leaf unknown to the scientists. Photos and a mold will go to a colleague specializing in ancient plants for identification. And Fiorillo spent time looking for the burrows of small invertebrate animals, similar to ancient crayfish. He’s convinced that’s not exactly what was living in the ancient burrows he discovered, but he said there’s still plenty they don’t know about the biodiversity of the Late Cretaceous era this far north.

“We put a model out there, shot it full of holes and now we need to discover what it means,” he said. “We’ve got lots of things to chew on in the wintertime.”

As he scribbled into his hard-sided, yellow notebook, he called to Kobayashi, his former PhD student. “I can’t think of anyone else telling this robust a story,” he said.

There are still discoveries to make about dinosaur life in Aniakchak. Fiorillo dreams of taking his exploration inland to search for the fossilized skeletal remains of the very same hadrosaurs who once roamed the region’s beaches.

“It’s just the first bone” said Fiorillo, who has developed a keen eye for spotting footprints. “Our eyes are not trained for them. . . . It’s just finding the first one.”

Emily Schwing

Emily Schwing has worked as an Alaska-based reporter for nearly two decades. She has produced work for Reveal, NPR, the New York Times and others.