By Andrew Stuart
The Triassic redbeds are one of the scenic highlights of West Texas. They dazzle in the red cliffs of Palo Duro Canyon and Caprock Canyons state parks.
These colorful rocks are found all along the margin of the Llano Estacado, and where rivers like the Brazos and the Pecos cut the great plateau.
The redbeds are also one of the world’s most important sources of fossils from the Triassic Period. In that distant time, strange and wondrous creatures roamed the Earth.
“It is a burning, seething cauldron, filled with dramatic light and color.” That’s what painter Georgia O’Keefe said about Palo Duro Canyon south of Amarillo.
The heart of that “cauldron,” the red rocks O’Keefe admired, are what geologists call the Dockum Group. As early as the 19th century, scientists knew the Dockum Group contained important fossils from the Triassic Period.
The Triassic lasted 51 million years. It began 252 million years ago, at the close of the Permian. It was followed by the Jurassic – the Age of Dinosaurs.
Most of us can visualize Jurassic fauna – the stegosaurus, brontosaurus and pterodactyl live in the imagination. But the Triassic creatures boggle the mind.
Bill Mueller is a paleontologist as the Museum of Texas Tech University in Lubbock.
“We’ve got the tanystropheus,” Mueller said. “The body was the size and shape of a turtle, without the shell, and they had a 6-foot-long neck – very strange-looking creatures. And we have procolophonids, which are another small reptile. We had trilophosaurids, which are very similar to an iguana. These were herbivorous. There were just a number of very unusual animals that were running around during the Triassic.”
The Permian ended with a sweeping extinction. Ninety percent of species vanished. That great die-off was followed by an explosion of biological diversity.
Phytosaurs – massive reptiles – swam the rivers. There were salamander-like amphibians – 12 feet long. Dicynodonts were common. They were synapsids – part of the lineage that includes mammals.
“One of my graduate students called them a ‘turtle-cow,’” Mueller said of the dicynodonts. “They’re about the size and shape of a cow, or a big hog. They have a beak like a turtle and two tusks like a walrus – very strange-looking animals.”
Mammals made their first appearance in the Triassic. The world’s oldest mammal fossil was found near Crosbyton, Texas.
“That was adelobasileus,” Mueller said. “They were very small, much like a rat – or a – well, pretty much like a rat.”
Near the town of Post, Texas Tech professor Sankar Chatterjee found a skull nearly 2 feet long. The skull belonged to a reptile with a body similar to a Tyrannosaurus Rex – but it was of a different lineage. He named it Postosuchus. It was the apex predator of Triassic West Texas.
Discoveries in the redbeds continue. At his research site in Garza County, Mueller has found 22 new animals. They’re yet to be named.
Fossils literally wash out of the rocks, Mueller said.
“I try to go down after every rain and survey the area,” he said, “because each rain may uncover something new, and the next rain, if I’m not there, may wash it away.”
Why is there such an abundance of Triassic fossils in West Texas?
Millions of years before the Triassic, tectonic forces had produced the Ouachita Uplift – mountains extending from present-day Brewster County to what’s now Alabama. In the Triassic, a river system larger than the Mississippi flowed west from those highlands. It emptied itself into the ocean near present-day Nevada. The fossils accumulated in the floodplains and lakes of this river system.
The end of the Triassic was marked by another mass extinction. That period’s distinctive creatures vanished.
Dinosaurs were small animals in the Triassic. But after the extinction, they began their march to dominance. Mueller said the Triassic can provide clues to how today’s creatures will respond to the effects of climate change.
Mueller said it’s a special privilege to have the Triassic redbeds in his backyard.
“It’s amazing what we’re finding,” he said. “We’re very fortunate to live very close to our research areas. We can run out almost any day and go do fieldwork. Who knows, this weekend we might find another new species.”
Visitors can see Triassic fossils at the Museum of Texas Tech. It’s a glimpse into a fascinating chapter in our natural history.