ONCE IT WAS A HOME on the range, where the bear-dogs and sabertooths preyed on five-toed horses and other critters that vanished millions of years ago from what today is Eastern Oregon's arid high desert.
The rhinoceros evolved here. There were oreodonts, ruminant pigs related to sheep and camels. Saber-toothed cats from the size of tigers down to small bobcats roamed the region.
"There is nothing like them today," said Superintendent Jim Hammett at the John Day Fossil Beds National Monument in Kimberly, Ore.
"What happened to them? All we know for sure is that we had them, then we didn't," said Scott Foss, curator of the park's new visitors' center and preservation laboratory.
The fossil beds of this national monument contain a rare continuum of 50 million years of plant and animal history, compared to 2 million or 3 million years at better-known fossil beds.
"That's a snapshot. Here, you get the whole movie," Foss said.
The plants and animals found fossilized here were not unique. But they were fortuitously preserved by minerals in volcanic ash, in a basin where the fossils were quickly covered and not washed away by erosion.
On fossilized ground
"For studying mammalian evolution this is one of the best places, simply because they were all here," Hammett said. "It is not far-fetched to say it is unique on Earth. It is one of the few national park areas that has a pure scientific mandate. The major part of our budget is spent on scientists."
And perhaps most importantly, said Ted Fremd, the monument's head paleontologist, the volcanic ash that layers the site can be dated by radioisotopes with great precision -- "serving as something like page numbers in a book with a 45 million-year-long plot."
Hammett said humans were in the area by about 10,000 years ago, not even a blip on the basin's time line. They were probably just passing through, he said.
"It's difficult to grasp how brief a time humans have been on earth," Hammett said. "That's our take-home message."
Soldiers found the first fossils in the 1860s and told Thomas Condon, a Presbyterian minister and amateur scientist in The Dalles to the north on the Columbia River. He tipped off the Eastern scientists, who boxed tons of fossils and shipped them to Yale, Princeton, the Smithsonian and elsewhere, where many remain.
Prime examples, or perfectly reproduced casts, remain at the museum at the Thomas Condon Paleontology Center in the park's Sheep Rock Unit, which is finishing up its newest wing.
Getting up close
In addition to fossil displays, visitors can watch through a large window as scientists and technicians work to preserve and restore fossils.
A more hands-on experience is available through the Oregon Museum of Science and Industry's weeklong summer programs at Hancock Station, providing a broad area of scientific exploration aimed mostly at younger visitors.
The national monument is on 14,000 acres in three scattered units in a remote but scenic chunk of Eastern Oregon's Grant and Wheeler counties.
Graduate students in paleontology come each summer to work the beds. But visitors are not allowed to keep -- or even pick up -- anything.
"We have a very hard line on collecting," Hammett said.
Trails at the monument are generally easy and range from a few hundred yards to three miles long. Some are wheelchair-accessible. However, most fossils can't be seen by the untrained eye.
"If you know what you are looking for, you will find [fossils]. But there are no big bones sticking out of the [canyon] walls," he said.
People who want to take a slice of prehistory home can go to the town of -- what else? -- Fossil, near the park's Clarno unit but outside the park itself. There, on a hillside behind the high school, amateurs can find mostly leaf fossils imprinted in shale. There is usually a $3 charge, and volunteers are there weekdays with instructions, hints and, in limited numbers, small shovels and claw hammers on loan. They will help you identify what you find.
You're better off taking your own tools, and a putty knife or something similar would be handy. After you dig out the layers of soft shale, use the claw of the hammer to gently start separating the layers, and pull them apart or use the putty knife to slowly pry, to see what's there.
Millions of years ago
A recent effort found good examples of metasequoia leaves that saw daylight for the first time in 25 million to 30 million years, and a number of other broader leaves. With a little patience, success at some level is a given.
It can be hard to envision today's dry hills of sage and juniper as the neotropical jungle thick with palms, banana trees and vines that they once were. Lava flows, the formation of the Cascade Range to the west and other changes gradually changed the climate and the species that could live there.
Grant County today is cattle and farm country not given to frills, and the cowboys are real.
The region is a photographer's heaven, especially in the Painted Hills unit, where the colors of the hills and cliffs seem to change with the weather and the position of the sun. Early morning and late afternoon are best.
About 120,000 people visited the John Day monument last year. Most spend a day or two amid the quiet hills that once teemed with long-gone life forms.
If you think back on what happened here, the urge to hurry slides away. If the wind is down and the birds are quiet, you can almost hear dust.
And as you may be reminded more than once, time in the fossil beds is measured in the millions of years.