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Finding the skull of a Palaeocastor may not be the sort of thing that excites the average person. In fact, before I met Dr. Joshua X. Samuels late last month, I might have thought that name belonged to some particularly unpleasant medicinal oil.

Samuels schooled me. The head of vertebrate paleontology at John Day Fossil Beds National Monument told me that a Palaeocastor was, in fact, a fossil beaver — a large burrowing rodent that inhabited the region of the John Day River valley about 25 million years ago.

“There are only two species of beavers on the planet today,” said Samuels, “but they have a great fossil record. At various times (through geological history), we have evidence of 40 species of beavers, both aquatic and burrowing. Three different kinds of beavers lived together here (near John Day) at the same time, filling different niches in the ecology.”

Samuels, 33, grew up in Jerome, Idaho, just down the road from the Hagerman Fossil Beds National Monument, where he first became interested in fossil beavers. During his undergraduate years at the College of Idaho, he studied anatomy to learn skeletal functions: “I wanted to figure out what extinct animals did,” he said. Then he earned a PhD in paleontology from UCLA, and four years ago returned to the Northwest, where he said he will be perfectly happy to spend the next several decades digging bones in the semi-desert.

“My second year here, I found the skull of a burrowing beaver,” he recalled with exuberance. “I had studied them for years, but I had never found a skull before. Then, last summer, I found a complete skeleton on Sheep Rock.”

He paused and relished the moment one more time. “That was really something,” he said.

Treasure trove

For a paleontologist — especially one like Samuels, whose professional interest is in rodents and small carnivores — the John Day Fossil Beds are a treasure trove.

“There really isn’t any other place on Earth like this,” said Theodore Fremd, curator and research associate at the University of Oregon Museum of Natural and Cultural History. Previously, Fremd was the national monument’s chief of paleontology (from 1984 to 2010). “Nowhere else has such a long sequence, 40 million years, of plants and animals during a time when the earth’s climate was going through profound changes. The landscape here gives us a look at the past like a fine-grained movie.”

Between 45 and 5 million years ago — long after the age of dinosaurs — Eastern Oregon was alternately covered by inland seas, marshy mudflats, volcanic ash and basalt and savannah. Thousands of species roamed these lands at various times: saber-tooth cats, crocodiles, rhinoceroses, giraffes and elephants, as well as sheep-like oreodonts and fanged, cat-sized mouse deer called tragulids. Plant life evolved from palms and banana trees to redwoods and grasslands. And the world’s most complete fossil record of this era is written in the John Day rocks.

Established in 1975, John Day Fossil Beds National Monument comprises three separate parcels, all of them along their namesake river or a tributary thereof. They occupy a collective 20 square miles of rugged High Desert, uninhabited except for National Park Service staff and the caretakers of an Oregon Museum of Science and Industry science camp. All are located within 2½ hours’ drive northeast of Bend, and each is distinctive in its own way.

Most scenically appealing to the average tourist are the Painted Hills, 93 miles from Bend, just north of U.S. Highway 26 near Mitchell. Layers of lake-bed sediments and fossilized soils have left an artist’s palette of vividly striped hummocks, bands of burnt-orange and ocher-yellow, olive-green and rust-red that lay a unique veneer upon the arid landscape. The Clarno Unit, 88 miles from Bend on state Highway 218 between Antelope and Fossil, harbors the richest, most diverse collection of botanical fossils anywhere.

I met Samuels at the Thomas Condon Paleontology Center. The centerpiece of the monument’s Sheep Rock Unit, 117 miles from Bend (on state Highway 19, north of U.S. Highway 26 west of Dayville), stands closest to the place where Thomas Condon — a pioneer Protestant minister and amateur scientist — first began excavating fossils in 1865.

Seven years later, Condon was appointed the first Oregon state geologist. He later became a professor of geology at the University of Oregon, a position he held until his death in 1907. Quite unlike other preachers of his time, Condon believed religion and modern science went hand-in-hand: “The church has nothing to fear from the uncovering of truth,” he wrote.

Exhibits in the 1920s James Cant Ranch, across Route 19 from the paleontology center, discuss Condon’s work. Park Service administrative offices are located on the second floor of the main ranch house, but most of the complex, including its working barn and orchards, has been preserved as it stood 90 years ago. The ground floor of the main house contains a museum of pioneer history in the John Day Valley.

Fossil relics

The Sheep Rock Unit contains several outstanding fossil quarries. In particular, two of them are worthy of note. Sheep Rock itself is a cap of erosion-resistant basalt that rises 1,100 feet above the river, through layers of volcanic ash-turned-claystone, shouting distance from the paleontology center. There are no public trails here — scientists manufacture their own routes — but in Blue Basin, 3 miles north, more than 4 miles of hiking trails invite public exploration.

“We are still finding new species here after 150 years,” said Samuels. Among the recent finds, he said, were the remains of a small pig-like animal, the size of a housecat, the first of its kind west of the Rockies. “It’s even rare on the Great Plains,” he said. “And no one had ever found them here before. It helps fill out the picture of the ecology.”

Another surprising find, he said, was that of a Sinclairella, a wood-pecking mammal similar to the aye-aye of Madagascar, with long fingers and protruding teeth used to get grubs from tree bark.

Samuels said he and his associate, technician Jennifer Cavin, devote a couple of workdays every week to fossil hunting. “We start with the knowledge of what’s been done before, which rock layers preserve fossils from which eras,” Samuels said. “A lot of what we’re doing is crawling on our hands and knees, looking for anything that sticks out. We don’t find skeletons very often. More commonly, we find individual bones, jaws and skulls.

“This is what I got into paleontology to do.”

While the national monument is charged with protecting fossils from vandalism, its job also “includes protecting fossils from natural forces and erosion,” Samuels said. “So every several years, we search all exposed areas for fossils.

That brings us back to beavers. “They were the first burrowing animals,” the scientist said. “Even today, they are good diggers. If there’s no stream to build their lodges, they burrow into banks. They have fossilized well because they spent so much of their lives either underground or underwater. We can see how they have evolved as a species.”

His prized species, the Palaeocastor, he said, was essentially a gopher-like ground squirrel — “a 2-pound beaver,” Samuels said.

Sheep Rock Unit

The collection in the Condon Paleontology Center numbers 50,000 fossil specimens — considerably more than the 35,000 kept at the University of Oregon.

Multi-tasking as a museum, a visitor center and a paleontology lab, the Condon Center opened in 2005, three full decades after the national monument was created. In addition to the lab, where ongoing work is easily visible behind a large viewing window, the center has a theater and an excellent museum interpreting the different geological eras investigated here.

The museum poses and answers questions about why people like Samuels and Fremd consider it important to study the past.

“A lot of my research is studying how things change through time,” Samuels said. “Part of what I’m trying to figure out is this: Can we adapt? The evidence is incontrovertible that the temperature of Earth has warmed, and in the last 100 years, is having a substantial impact. Changes are happening at a much greater rate than in the past.”

His own studies of rodents and small carnivores yield plenty of evidence to that end, Samuels said. “As habitats become drier and more open, lifestyles change. Over a long time, we have seen tree-climbing animals vanish, as burrowing and jumping animals thrive in arid habitat. Some animals thrive. Others go extinct.”

I spent a couple of hours exploring the trails at Blue Basin. The 0.8-mile Island in Time Trail climbs among the basin’s blue-green clay-stone walls, created about 29 million years ago, to a desolate cirque of otherworldly mystique. Along the way, interpretive signs highlight such discoveries as tortoises and saber-tooth cats, displaying fossil replicas, not the real things. The more strenuous, 3.2-mile Overlook Trail circles the basin for marvelous panoramic views from a higher elevation.

Clarno Unit

The oldest fossils in the John Day preserve are at the Clarno Nut Beds, dating from 45 million to 40 million years ago. In this era, Oregon’s climate was subtropical. Banana and palm trees, sycamores and dogwood trees, thrived in the hot, wet conditions.

“This is the greatest diversity of fossil wood anywhere on earth,” raved Fremd. “We’ve found 333 different species of plants, seeds, leaves, flowers, roots and wood, including 76 types of wood alone … and 175 species of fruit and nuts. Normally you’d just find leaves or pollen.”

Rhino-like brontotheres and ungainly, semi-aquatic amynodonts were conspicuous because of their great size. Saber-tooth cats and leaf-eating horses were also denizens of the region. They were among 2,000 specimens recovered from the Hancock Mammal Quarry, a 23-foot-deep layer of volcanic sediment swept by seasonal flooding to a point bar about 40 million years ago.

Today, that quarry is close to the Hancock Field Station, a scholastic science program run by the Portland-based Oregon Museum of Science and Industry. Young people on study programs of a week or longer are exposed not only to paleontology and geology, but also to astronomy and natural history. There is dormitory lodging, a central mess hall and a hanging replica skeleton of a prehistoric mammal dubbed “Dead Ed.”

Miles of trails extend from here to the mammal quarry, the nut beds and other fossil sites. They’re not indicated on the national monument website nor in its brochures, and casual visitors are not normally invited to visit the Hancock Station. But keen hikers can park outside the gates of the OMSI camp to follow trails into the foothills on its perimeter.

The main point of visitor interest at Clarno is the Palisades. Two trails begin at the foot of these rocky spires, the legacy of ash-laden mudflows known as lahars, rising steeply above Highway 218. I took a short hike up the Trail of the Fossils and was stunned by the wealth of plant fossils in the rocks, even in this public area. Interpretive signs identified numerous plant remains, including subtropical sycamore leaves and tree trunks.

Painted Hills

While Clarno fossils date back to about 45 million years ago, those of the Bridge Creek Strata in the Painted Hills are considerably younger — about 33 million years old.

There are four trails in this section of the park, none longer than 1.7 miles. I ventured out upon each of them. From the Painted Hills Overlook Trail, I got several perspectives on this vibrant landscape, its appearance changing as clouds came and went. Here, the striations of paleosols, or fossil soils, layered between sediments left by ancient lake beds, have created a colorful and mineral-rich canvas. Twenty-nine different minerals have contributed to the hues of these barren clay hills.

Climbing the hillside on the Carroll Rim Trail, ascending the south-facing slope above the Painted Hills, I was rewarded with an almost-aerial perspective on the colorful landforms.

Elsewhere in the Painted Hills Unit, the Painted Cove Trail wound me through red and gold clay-stone hills on an elevated walkway; from this angle, they appeared as giant mounds of colored popcorn. And the Leaf Hill Trail led past a rather uninteresting looking mound that was, in fact, the site of major scientific finds in the 1920s and 1990s — among them the discovery of the meta-sequoia or “dawn redwood,” which disappeared from Oregon 5 million years ago.

There were no fossil beavers here. But in a preserve that holds the variety of the John Day Fossil Beds, there is room for everyone of a certain age.

— Reporter: