Paleocene Mammals and Albert Silberling

By editor

Harlowton, Wheatland County, Montana

Sixty-six million years ago, a celestial visitor altered the course of life on Earth. The asteroid impact that closed the Cretaceous period extinguished the reign of the dinosaurs, leaving behind a world both raw and ripe for renewal. From the ashes of that extinction emerged the Paleocene epoch, a chapter spanning roughly ten million years when mammals, once relegated to the shadows, began to claim the land. In the heart of central Montana, the Fort Union Geological Formation holds the fossil record of these early mammals, creatures that would eventually give rise to the diverse fauna of the modern world.

The Fort Union Formation stretches across parts of Montana, Wyoming, and North Dakota, its layers capturing the story of an ancient subtropical landscape. In this region near Harlowton, rivers originating from the southwestern mountain slopes of Montana carried vast sediment loads--sand, silt, clay--from swampy coastal plains far to the east into a shallow inland sea. These sediments buried thick mats of peat and swamp vegetation, which over time transformed into coal seams. The slow accumulation and compaction of these materials produced sandstones, siltstones, and mudstones, relatively soft rocks prone to erosion, allowing the badlands and coulees of Wheatland County to reveal their buried histories with each shifting season.

It was upon this land that Albert Silberling, a homesteader and farmer without formal scientific training, cultivated more than crops. Silberling’s patient gaze and intimate knowledge of the land’s rhythms led him to discover fossils that would illuminate a critical era in Earth’s history. Beginning in 1902, Silberling worked alongside Earl Douglass, a paleontologist from Princeton University renowned for his work in dinosaur fossils. Together, they excavated a quarry southwest of Harlowton, unearthing primitive mammal remains that would redefine understanding of Paleocene biodiversity in North America.

The mammals Silberling found were small, often no larger than a squirrel, but they carried within their bones the blueprint for the future. Among the recovered species was Ptilodus, a genus of multituberculate mammals that thrived during the Paleocene. Multituberculates, characterized by their multiple rows of tubercles on molars, were among the most successful mammalian groups of their time. Ptilodus itself had a lineage stretching back to the middle Jurassic, approximately 160 million years ago, coexisting with colossal sauropods like Apatosaurus and Diplodocus, and fierce carnivores such as Allosaurus. These early mammals survived the cataclysm that ended the dinosaurs and adapted to fill the vacated niches.

The anatomy of Ptilodus reveals much about its lifestyle. Its dexterous feet and prehensile tail suggest arboreal habits, navigating the dense subtropical forests that covered Montana during the Paleocene. The climate then was warm and humid, supporting lush vegetation that included early broadleaf trees and ferns. Such a habitat provided shelter and sustenance for these nimble mammals, which likely fed on seeds, insects, and perhaps small plants. The success of Ptilodus and its relatives in this environment illustrates how mammals began to diversify rapidly after the dinosaur extinction.

The quarry excavated by Silberling and Douglass, along with three others explored over the subsequent four decades, yielded remains of at least twenty-three species. These specimens form the foundation for scientific knowledge about early Paleocene mammals in this region. Silberling’s dedication to collecting and preserving fossils, despite his lack of formal education, earned him recognition in the scientific community. Several species discovered in Wheatland County bear his name, a tribute to the contributions of a man who read the land with the skill of a naturalist.

Albert Silberling’s work reminds me of the words of John Wesley Powell, the great explorer and geologist of the American West, who said, “The earth, and the life upon it, are ever changing. No man can truly know the land unless he watches its slow transformations.” Silberling watched patiently, season after season, as the frost heaved new fossils from the soil, as erosion carved deeper into the badlands, revealing bones and teeth that had slept for millions of years.

The process of fossil discovery in this region continues today. Each spring, the freeze-thaw cycles of Montana’s harsh winters crack open the earth, exposing fragments of ancient life. The coulees, with their steep walls and scattered boulders, guard these treasures jealously, yielding them only to those with persistence and a careful eye. Walking these slopes, one can almost feel the passage of deep time beneath one’s feet--the sedimentary layers representing epochs of climate, ecological shifts, and evolutionary milestones.

The significance of the fossil record in central Montana extends beyond the identification of individual species. It provides a window into the recovery of life after one of Earth’s greatest extinctions, the adaptation of mammals to new environments, and the geological forces that shaped the landscape. The Fort Union Formation captures a moment when the planet was changing rapidly, and life was responding with innovation and resilience.

This region also connects us to the broader story of the Cenozoic era, sometimes called the Age of Mammals, which began with the Paleocene. It was a time when mammals diversified into forms that would eventually include modern horses, deer, bears, and primates. The humble fossils uncovered by Silberling and his contemporaries are the earliest chapters in this saga.

As I stand on the badlands near Harlowton, I consider the layers of stone that compose the earth beneath my feet--mudstone, siltstone, and sandstone, each a page in an ancient volume. The dry wind carries the scent of sagebrush and the distant song of a meadowlark, while the sun casts long shadows over the coulees. In this quiet place, the deep past is not distant but palpable, inscribed in bone and stone.

Albert Silberling’s legacy endures not only in the fossils he uncovered but in the example he set--a reminder that curiosity, patience, and a close relationship with the land can reveal the secrets of ages long past. His discoveries at Harlowton enrich our understanding of the natural world and invite us to continue exploring the rugged terrain where Earth’s history lies just beneath the surface.

See also

• Paleocene Mammals and Albert Silberling at Harlowton, Wheatland County
• The Great Inland Seaway at Columbus, Stillwater County
• The Hell Creek Formation at Jordan, Garfield County