Hidden in the vast and untamed wilderness of southern Chile lies one of the country’s greatest paleontological treasures—Sierra Baguales. Just 120 kilometers northwest of Puerto Natales, this black, serrated mountain range rises dramatically on the right side of the road leading to Torres del Paine National Park. Mysterious and haunting in appearance, it marks the very frontier with Argentina and guards within it a secret that few travelers ever discover: the most significant fossil site in Chile.
A Journey Through Deep Time
Walking across the remote landscapes of Sierra Baguales is not just a trek through a wild, silent corner of Patagonia—it’s a journey through millions of years of Earth’s history. The region reveals a geological and biological timeline unlike any other in the country, with a fossil record of ancient flora and fauna layered like the pages of an open book.
From petrified forests of eucalyptus and prehistoric ferns to seashells embedded in wind-swept rock faces, Sierra Baguales tells a story that predates even the most ancient civilizations. This 60-kilometer-long mountain range separates the basins of two rivers—the Baguales and the de las Chinas—each of which has its own tale to tell.
The valley of the de las Chinas River holds evidence of the final 20 million years of the dinosaur era, while the Baguales River chronicles the rise of mammals in all their varied forms and sizes. Together, these valleys form a natural library of prehistoric life.
From Ocean Floors to Forest Canopies
The history of Sierra Baguales begins more than 100 million years ago, during the Cretaceous period, when Patagonia began to separate from Antarctica. At that time, the landscape was a mosaic of temperate forests and ancient seas, teeming with life.
Massive titanosaurs once roamed the dense vegetation alongside hadrosaurs, or “duck-billed” dinosaurs, that moved in herds. Later, the land sank beneath the ocean, transforming the area into a deep-sea ecosystem where marine reptiles like mosasaurs and plesiosaurs swam. As time passed, the sea became shallower, giving rise to a vibrant marine world populated by crocodiles, turtles, penguins, and a wide array of sharks.
One of the most extraordinary discoveries here is that of archaeocetes—primitive whales from the middle Eocene epoch, about 45 to 40 million years ago. These early cetaceans still possessed four legs and could move on land, representing a crucial evolutionary bridge in the transition from land-dwelling to fully aquatic mammals. Sierra Baguales is the only place in Chile where these fossils have been found.
A Dynamic Landscape of Change
The fossil-rich layers of Sierra Baguales are evidence of an ever-changing environment—one shaped by powerful geological forces and the rising and falling of ancient seas. It was once submerged, then exposed. Forests turned into seabeds and back again. Delta systems, coastal plains, and inland basins emerged and disappeared, forming a complex ecological mosaic.
The speed of these changes varied dramatically—some were sudden, others slow and subtle—but all left a permanent mark on the region. Today, researchers can trace how climate, sea levels, and species evolved in this dynamic landscape.
A Biogeographical Borderland
Paleontologists often refer to Sierra Baguales as a kind of customs checkpoint between South America and Antarctica. Tens of millions of years ago, when both continents were lush and green, a biological bridge allowed plants and animals to migrate between them.
One of the best examples of this exchange is the Nothofagus genus—a family of southern beech trees. Still thriving in Chile today, 10 of the world’s 35 known species of Nothofagus are native to the country. These trees include the roble, raulí, lenga, and coihue, and all are thought to have entered South America from Antarctica roughly 68 million years ago, in three distinct migratory waves.
The first wave brought the ancestor of the ruil, a tree now nearly extinct and limited to a tiny area in Chile’s Maule region. The second wave contributed to the lush Valdivian rainforest. The third and final wave, just before the land connection vanished, saw the arrival of the coihue, which now dominates the frigid forests of Magallanes. Its thick, waxy, evergreen leaves are a testament to evolutionary adaptation and resilience.
The Early Fossil Hunters
The first mentions of fossils in Sierra Baguales came over a century ago, thanks to local baqueanos—Patagonian horsemen—who told tales of strange stones resembling bones and shells. Occasional fossils were found, but it wasn’t until 2006 that the area received formal scientific attention.
That year, Dr. Teresa Torres González, a paleontologist from the University of Chile, initiated a systematic exploration of the region. Despite the harsh conditions—bitter winds, snow, and near-constant rain—the team uncovered a staggering array of fossilized life, exceeding all expectations.
The nearby hamlet of Cerro Guido soon became the logistical base for field expeditions. For the past 15 years, scientists and students from around the world have gathered here each summer to dig, study, and share their findings. The result is a growing body of knowledge that is radically altering our understanding of Patagonia’s prehistoric past.
What makes the research even more powerful is the interdisciplinary nature of the team. Biologists, geologists, paleobotanists, and dinosaur experts work side by side. Together, they are not only uncovering fossils but also reconstructing long-term climatic shifts and ecosystem transformations.
This work underscores the importance of preserving the fossils in situ. Removing them from their context or taking them as souvenirs destroys valuable scientific information. The public must be educated to respect and protect these fragile time capsules.
Trekking into Isolation
Despite its scientific significance, Sierra Baguales remains largely unknown to tourists. Unlike the crowded trails of Torres del Paine, it offers total solitude and an unspoiled connection to nature. Here, one truly feels like an explorer.
To visit, travelers must register with the Carabineros station in Cerro Guido, as the area lies on an unregulated international border with Argentina. Most of the land is private, composed of large estancias dedicated to sheep farming, although many are now incorporating wildlife tourism and paleontological treks into their offerings.
Hikers should be prepared for rugged terrain and no official trails—only animal tracks, mostly made by guanaco herds. Along the way, one might come across the bones of guanacos and sheep, stark reminders that this is puma territory.
The puma, or mountain lion, is the apex predator of the region. While some pumas in Torres del Paine are habituated to human presence and a common sight for high-end eco-tourists, the pumas of Sierra Baguales are still completely wild. Visitors must exercise caution—especially near pumas feeding or caring for their cubs.
Indigenous Legacy
There’s more to Baguales than just fossils and wildlife. High in the hills lies a chenque, or ancient burial site, believed to have belonged to the Aonikenk people who lived in this region for over 6,000 years. These indigenous groups considered the mountains sacred, inhabited by supernatural spirits.
In their search for obsidian, which is abundant in the region and ideal for crafting projectile points, the Aonikenk would have come across fossils—possibly mistaking them for the remains of mythical creatures. The cultural and spiritual significance of these discoveries adds another layer to the mystique of Baguales.
The La Cumbre-Baguales Paleontological Complex
One of the key figures in the modern preservation of Sierra Baguales is José Luis Oyarzún, who began exploring the region 30 years ago. Realizing the site’s potential, he collaborated with estancia owners, scientists, and environmentalists to develop a long-term plan for research and conservation.
This led to the creation of the “La Cumbre–Baguales” Geo-Paleontological Complex, a privately protected area and home to some of the most important fossil beds in Chile. The main mission of the project is to study, conserve, and educate.
The impact has been substantial. Visitors, though still relatively few, are often overwhelmed by the beauty and significance of the place. Educational initiatives are underway to involve local schools and communities, fostering a sense of ownership and responsibility for the site’s protection.
Plans are also in motion to establish a paleontological museum in Puerto Natales, where the fossils currently held in storage could be displayed to the public. Such a museum would serve as a window into Patagonia’s deep past, showcasing the incredible findings from this remote and enigmatic region.
A Future Shaped by the Past
Sierra Baguales is more than just a mountain range—it is a time machine, a mystical landscape, and a scientific treasure trove. In a world where so much of nature has been mapped, explored, and domesticated, Baguales stands as one of the last frontiers. Its isolation, mystery, and the sheer magnitude of its fossil heritage make it a place worthy of international recognition and protection.
Whether you’re a scientist, a hiker, or simply a lover of wild, untouched places, Sierra Baguales offers an unparalleled opportunity to connect with the Earth’s distant past—and perhaps help shape its future through responsible stewardship and curiosity.
