New Mexico’s Ancient History

A new hall at the New Mexico Museum of Natural History & Science explores our state’s prehistoric life

By Stephen Hamway

What comes to mind when you think of prehistoric life? Odds are, you’re picturing a scene from the time of dinosaurs: a mighty Tyrannosaurus rex roaring, a long-necked Brachiosaurus eating leaves atop a massive tree, or a pack of velociraptors ganging up on their prey. 

But what came before the dinosaurs? How did they eventually come to take over the planet? When and how did the animals that came before them start to walk on land, develop limbs, and breathe air? Hundreds of millions of years before the dinosaurs, what did the most ancient known life on our planet look like, and how did it shape the evolution of life for millions of years to come?

The newest permanent exhibition at the New Mexico Museum of Natural History & Science in Albuquerque, the Bradbury Stamm Construction Hall of Ancient Life, explores these questions by tracing nearly 300 million years of natural history and evolution in what’s now New Mexico. Through more than 300 never-before-seen fossils collected from across our state, this new hall tells the story of the ancient plants, fish, amphibians, invertebrates, and reptiles that once called our state home. In doing so, it completes much of the museum’s story of life in New Mexico, one that’s more than half a billion years in the making, for kids and adults alike. 

The Bradbury Stamm Construction Hall of Ancient Life tells the story of the Paleozoic Era, which began almost 540 million years ago. Earth was a very different place back then, with no life on land, and landmasses that looked little like the continents we think of today. The Paleozoic was a time of great change, and most of the major kinds of plants and animals evolved during this era. The first clams, snails, corals, fishes, trees, insects, amphibians, and reptiles all evolved during the ensuing 290 million years of the Paleozoic, as life expanded out of the oceans and onto dry land. Additionally, the modern continents began to take shape, drifting toward their current locations. In many ways, our world today has its foundations in the Paleozoic Era.

Here in New Mexico, we see how the environment and landscape changed by studying the Paleozoic rocks and fossils. Based on the fossil record, scientists believe that the landmass that would become our state was in a completely different location on earth’s surface. From 500 million years ago until around 350 million years ago, the land that would eventually come to comprise New Mexico was located just below the equator. Shallow tropical seas comprised much of Southern New Mexico during that time, while the northern portion of our state consisted mostly of hilly and mountainous terrain. 

The seas covering Southern New Mexico during this period left behind layers of rocks and minerals, and from these layers, we know that these shallow seas teemed with life. The oldest fossil ever discovered in New Mexico, a 500-million-year-old underwater invertebrate known as a trilobite, was uncovered in the Caballo Mountains of Southern New Mexico, and is part of the exhibition hall for visitors to view. Later, a diverse set of ancient invertebrates and bony fish called our state home. 

Over the course of millions of years, these seaways eventually expanded to Northern New Mexico as well. During the Pennsylvanian Period, which ended around 320 million years ago, New Mexico was a network of islands surrounded by tropical seas. This meant that our state was one of the places where life was able to make the jump onto dry land, one of the greatest changes our planet has ever seen.

One well-known site showcasing these changes was Kinney Brick Quarry. Located in the Manzano Mountains east of Albuquerque, Kinney Brick Quarry is a clay pit that is being commercially mined to make bricks. Today, it is one of the most famous fossil sites in the world. With fossils of sharks—including the fearsome Dracopristis or Godzilla shark—alongside fossilized fishes, plants, clams, amphibians, millipedes, spiders, and cockroaches, Kinney Brick Quarry showcases the broad diversity of life in New Mexico during this period, and provides a snapshot into the rise of life on land. Dracopristis and a number of fossils from this site will be part of the Bradbury Stamm Construction Hall of Ancient Life. 

Cañon del Cobre, located in Rio Arriba County near Abiquiu, is another New Mexico site famous for fossils. Around 300 million years ago, this part of Northern New Mexico was a floodplain shrouded in low-lying wetland forests of seed ferns, giant horsetails, and clubmosses the size of trees. It was these sodden forests that gave rise to Arthropleura, the largest arthropod ever known. Known only from its fossilized footprints, or trackways, this giant, millipede-like monster hunted alongside massive amphibians and early reptiles in this part of Northern New Mexico.

At times during the Paleozoic Era, New Mexico looked more like it does today. During the Permian Period, which spanned 299 to 252 million years ago, New Mexico was part of the vast supercontinent of Pangea, which experienced extreme wet and dry seasons, not unlike the monsoon rains New Mexico receives in modern times. A vast mountain range running east-west along western North America divided the landscape and was known as the Ancestral Rocky Mountains: geologically separate from, but still reminiscent of, the Rocky Mountains we see out our windows today. Near the end of this period, the climate dried and a vast desert spread across the Four Corners region. Sound familiar? 

This period even showcases early ancestors of mammals. A group of four-legged land animals known as Eupelycosaurs evolved during the Permian Period, including the famous sail-backed Dimetrodon. While these animals are sometimes mistaken for dinosaurs, they’re actually more closely related to mammals, with a skull structure that distinguishes them from reptiles. Every mammal, humans included, traces its lineage back to these early ancestors. 

After nearly 300 million years, the Paleozoic Era ended with a bang: eruptions of the Siberian traps, a volcanic field the size of the United States, spewed tons of carbon and sulfur dioxide into the air. These chemicals rapidly made oceans more acidic and turned an already-warming world into a runaway greenhouse. This led to the largest extinction in earth’s history, more catastrophic even than the end of the age of dinosaurs. More than 90 percent of marine species went extinct, forever changing our oceans. On land, nearly two-thirds of vertebrate species were also wiped out. 

Despite its catastrophic end, so much of what we think of as life today has its roots in the Paleozoic Era. Fish, amphibians, reptiles, even plants, evolved during this time. Even its fiery end gave rise to the most dramatic group of land animals the world has ever seen: dinosaurs. Here in New Mexico, we’re fortunate to have been on the front lines of many of these changes, with some of the best-preserved fossils from this era. Today, visitors from New Mexico and around the world can view these fossils for the first time in the Bradbury Stamm Construction Hall of Ancient Life, on the second floor of the New Mexico Museum of Natural History & Science.

Stephen Hamway is a public relations specialist for the New Mexico Department of Cultural Affairs. His work supports a trio of NMDCA divisions, including the New Mexico Museum of Natural History & Science. Learn more at nmculture.org.