Beneath Ohio’s familiar landscapes lies a story that goes back hundreds of millions of years. It’s a story built by tropical seas, lush prehistoric forests, Ice Age giants, and the first Ohioans.
At the Cleveland Museum of Natural History, these chapters of the past are preserved in incredible detail, not just as unknown specimens from around the world, but as evidence discovered right here in Ohio. In fact, more than 80% of the Museum’s collections are Ohio-based, forming an invaluable record of our region’s biodiversity, natural history, and environmental changes over time.
These specimens invite us to take a closer look at the ground beneath us—and to imagine the very different worlds that once existed here.
An immersive display of Dunkleosteus brings this ancient fish to life in the Museum's Evolving Life Wing.
An Age of Fishes
Imagine standing in northern Ohio nearly 400 million years ago, during what is now known as the Devonian Period—or, as some call it, the Age of Fishes. Instead of forests or cities, you would be submerged beneath a warm, shallow tropical sea full of life. Coral reefs stretched across the sea floor, and strange, shell-like creatures called brachiopods clustered in abundance—so common, in fact, that they remain one of the most frequently found fossils in Ohio today.
Dominating this underwater world was Dunkleosteus, one of the most formidable fish of its time. With a body encased in bony armor and jaws that functioned like self-sharpening blades, Dunk was the apex predator of Ohio’s ancient seas. Fossils of Dunkleosteus have been found in the Cleveland Shale, making it a powerful symbol of Ohio’s deep past. Museum scientists, including Peter Bungart, Dr. David Dunkle, and Dr. Jesse Earle Hyde, contributed to many of these discoveries.
You can explore this ancient ocean in the Museum’s Larry Sears and Sally Zlotnick Sears Dynamic Earth Wing, where fossilized corals, brachiopods embedded in limestone, and dramatic reconstructions of Dunkleosteus bring this long-lost ecosystem to life. And don’t miss the immersive display of Dunk in the Evolving Life Wing, where you can see a life-size display of this fearsome fish swim by. Together, these specimens reveal a thriving marine world and remind us that Ohio’s ancient landscape looked vastly different.
Additional specimens found in the Evolving Life Wing, such as this fossil of Neuropteris ovata, an ancient seed fern, leave behind a near-perfect imprint of nature's past.
Carboniferous Swamps
Time-travel a hundred million years into the future, and you would find yourself in the middle of the Pennsylvanian period, roughly 300 million years ago. As time passed, the seas receded, and Ohio transformed once again. In their place grew vast, swampy ecosystems—humid, oxygen-rich environments filled with towering, unfamiliar plants. This was not a forest as we know it today, but something more alien: a dense landscape of giant club mosses, early ferns, and spore-bearing trees.
Among them was Lepidodendron, a lycopsid (or type of vascular plant) that could reach heights of over 100 feet. Fossilized trunks of Lepidodendron aculeatum, on display in the Museum’s Evolving Life Wing, offer a glimpse into these ancient wetlands, preserving their texture in remarkable detail. Despite their immense size, these trees often grew far apart, allowing smaller plants to thrive below. Other lycopsid tree species, like Sigillaria, adapted to drier conditions, extending their roots deep into the ground to access water even as climates began to shift.
While many of the flora and fauna preserved in Ohio’s fossil record look very different from the plants and animals we see around us today, the relatives of some of these species still thrive in present-day Ohio. Over time, the dense plant matter in these swamps was buried and compressed, forming the coal deposits found in Ohio and nearby regions.
Ice Age Giants
Fast forward to a much more recent chapter—one that, in geological terms, feels like yesterday. During the last Ice Age, which ended around 11,000 years ago, massive glaciers advanced and retreated across Ohio, carving the landscape and leaving behind the lakes, rivers, and landscapes we see today—including the Great Lakes found in our region.
In this colder, shifting environment roamed some of the most iconic animals in Ohio’s history: mammoths and mastodons. In the Museum’s Dynamic Earth Wing, you can come face-to-face with an American mastodon, a shaggy, tusked relative of modern elephants that once ambled through Ohio’s forests. Unlike its cousin, the woolly mammoth—which grazed on grasses in open landscapes—the mastodon had pointed teeth adapted for chewing twigs and leaves.
A remarkable discovery in Cleveland in 1909 uncovered the jaw of a juvenile mammoth buried deep beneath the city streets, offering a striking reminder that these giants once walked where we do today. Both species disappeared around 10,500 years ago, likely due to a combination of climate change and human activity.
A Land of Megafauna
Mammoths and mastodons were not alone in Pleistocene Ohio. This epoch was home to a remarkable diversity of megafauna—animals that seem almost mythical in size compared to those we’re familiar with today. Among them was Jefferson’s ground sloth, a massive herbivore with powerful limbs and large claws, adapted for pulling down vegetation rather than climbing trees like modern sloths.
Fossils of these giant-clawed animals, along with those of peccaries like Platygonus and even giant beavers, reveal a complex ecosystem of large mammals adapted to a changing climate. Some species, like the modern beaver, have survived with relatively little change. Others vanished at the end of the Ice Age, leaving only fossils behind.
These specimens, displayed in the Dynamic Earth Wing, help us understand not only what lived here, but also how ecosystems respond to environmental shifts—a story that continues to inform science today.
A Clovis point, hide-scraping tool, and bone spear point pictured next to two vertebrae from the spine of an American mastodon, all objects found in Ohio.
The First (Human) Ohioans
As the glaciers retreated and the climate warmed, a new presence entered the landscape: humans. Among the earliest to arrive in Ohio around 13,000 years ago were members of the Clovis culture, skilled hunters who adapted to a rapidly changing world.
In the Museum’s Evolving Life Wing, you can see tools discovered at the Paleo Crossing site in Medina County, as well as Sheriden Cave in Wyandot County. These artifacts, including spear points, hide-scraping tools, and large and small flake knives, offer a tangible connection to Ohio's early inhabitants. These tools were likely used to hunt and process large animals, including mammoths, and reflect a deep understanding of the environment. Museum archaeologists, including Emeritus Curator of Archaeology Dr. Brian Redmond, led the discovery and excavation of many of these artifacts.
The arrival of humans marks a turning point in Ohio’s story. As people spread across the landscape, they interacted with—and may have contributed to the disappearance of—many Ice Age species. Through the artifacts they left behind, we begin to see not just natural history, but human history intertwined with it.
Pictured above is Singer Lake Bog, among the 12,500 acres of natural areas protected by the Museum.
Ohio’s Living Landscape
In the thousands of years since, Ohio has continued to evolve into the landscape we recognize today. Forests returned, wetlands formed, and a rich diversity of modern life took hold across the region. This is the world of the Eastern deciduous forest—a tapestry of ecosystems that support countless species.
Yet this landscape has also been shaped by human activity. Cities, farms, and infrastructure have replaced many natural habitats, creating new challenges for biodiversity. Today, the Museum’s exhibits highlight both the richness of Ohio’s ecosystems and the importance of protecting them.
Through its Natural Areas Program, the Museum actively stewards more than 12,500 acres across northern Ohio, conserving fragile environments and supporting the health of our region. These efforts, along with the Museum’s collections themselves, ensure that Ohio’s natural history is not only preserved, but actively sustained.
A Story Still Unfolding
There is far more to Ohio's natural history—and these snapshots only offer a glimpse into the incredible world that came before us. From ancient seas to modern ecosystems, Ohio’s natural history is a story of constant change, written in the geology and fossils preserved beneath our feet and simultaneously carried forward in the landscapes around us.
At the Cleveland Museum of Natural History, these stories come to life through the objects in our care—many of them discovered right here in Ohio by Museum scientists. To see them in person is to come face-to-face with the creatures and environments that shaped this place long before us. And in doing so, we are reminded that understanding the past is essential to shaping the future.
Plan your visit today and see Ohio’s natural history up close!
