[Illustration: James H. Cook examines a fossil fragment at the quarries near Agate Springs Ranch about 1918.] [Illustration: Besides fossils, Cook also collected Indian artifacts and kept many of them on the walls of his study in the ranch house.] Worlds of Past and Present Imagine that you are a healthy young man, raised conservatively in Michigan several years after the end of the Civil War. You are a skilled all-around hunter and trapper. The railroad has just spanned the continent, and stories of the West, its dangers, its people, and its opportunities come to you frequently. You and a friend decide you must see this land for yourself, and you save your money carefully against the day when you will be ready to go west. Around 1869, at age 12, that day comes. At Fort Leavenworth, Kansas, you meet several cattlemen who tell you and your friend where to get work as cattle herders. Before many years have passed you have been a cowpuncher in Texas, you have fought Comanches, and you have bossed a ranch crew for a wealthy Englishman. You go on to fight the famous Apache Chieftain Geronimo as a scout with the U.S. Cavalry, and you befriend a famous Sioux chief, Red Cloud. You marry, buy a ranch in western Nebraska, and raise a family. And you become something of a legend in your own time, your ranch known for its hospitality to Indian, scientist, traveler—to one and all, rich or poor. A movie script? Not at all—these are the essentials of the life of James H. Cook. Known as “Captain,” James Cook became the owner, in 1887, of the Agate Springs Ranch, founded earlier by his father-in-law. Under Cook’s watchful eye, the ranch prospered and became a second home both for the Oglala Sioux and for paleontologists bent on excavating the fossilized remains of the life of 20 million years ago, found here along the Niobrara River in western Nebraska. This land, now encompassing Agate Fossil Beds National Monument, is punctuated with low bluffs ascending westward toward the Rockies. It is a land of sharp contrasts, of cool, inviting riverbanks and parched ridges, the most famous of which are the fossil-bearing Carnegie and University Hills. The surrounding grassy plains are a tapestry of wild grasses—prairie sandreed, blue grama, little bluestem, and needle-and-thread. The wildflowers lupine, spiderwort, western wallflower, sunflower, and penstemon add touches of blue, purple, orange, yellow, and red to the tapestry. In summer the dark green spears of the small soapweed, a yucca, dot the brown grasses of the hillsides. And just as they did more than 20 million years ago, cottonwoods and willows provide shade and shelter for birds and other animals along the river.