Jurassic sea creatures once swam across Texas and north Mexico, new plesiosaur fossil records show

Scientists have discovered bone fragments from the fin-like limbs and spine of a plesiosaur — an aquatic reptile from the Jurassic period — excavated thousands of feet above sea level in the Malone Mountains of western Texas.

The new find offers a glimpse into the shallow sea that once covered the arid deserts of northeastern Mexico and western Texas 150 million years ago.

Texas during the Late Jurassic, the era of the largest and most famous dinosaurs on Earth, is still largely a mystery to paleontologists due to the state’s limited amount of intact Jurassic-era rock formations.

Nearly all that remains of the Jurassic Texas ocean floor can be found along just 13 square miles of rock atop the Malone Mountains.

But with this new discovery of the plesiosaur, the hunt for more fossils has begun.

“Geologists are going out to find more bones,” said Louis Jacobs, a vertebrate paleontologist, the co-author of the new study. “They’re going to find them.”

Geoscientist Steve May of the University of Texas at Austin has discovered bone fragments (pictured) of the fin-like limbs and spine of a plesiosaur, the aquatic reptile of the Jurassic Period, in the Malone Mountains of western Texas. May says: ‘There is still more to discover’

The weathered remains of the plesiosaur were unearthed during two fossil-finding expeditions led by geoscientist Steve May, a research fellow at the University of Texas at Austin.

“There is still more to discover that can tell us the story of what this part of Texas looked like during the Jurassic,” May said in a statement from UT Austin.

May hopes that he and Jacobs’ paper on the bones and other fossils, as published this week in the peer-reviewed journal Rocky Mountain Geologywill encourage more dino hunting in the Malone.

“People, there are vertebrates from the Jurassic,” May said.

Just 13 square miles of rock along the Malone Mountains make up almost all that’s left of the Jurassic Texas ocean floor. The new discovery opens the hunt for more fossils

Before May’s discovery, the only fossils found in Texas from the Jurassic period were ancient shellfish-like invertebrates, including ammonites and snails.

But May and his team had picked up an important clue that there were even larger fossil remains in the Lone Star state.

A 1938 paper on the geology of the Malone Mountains by a future professor of geology at Southern Methodist University (SMU), Claude Albritton, casually mentioned large unidentified bone fragments.

The lead was enough to entice May to the Malone Mountains, after the geoscientist learned in 2015 that no Jurassic bones currently existed in the Texas fossil record.

“You just don’t want to believe there aren’t any Jurassic bones in Texas,” May said.

While the researchers note that the newly discovered plesiosaur fossils have eroded and broken up, Jacobs, a professor emeritus at SMU, expects scientists to now “look for the other things that interest them” around the Malone.

During the Jurassic, the sediments that would become the Malone Mountains settled within a few miles of the prehistoric coastline.

According to the researchers, the Malone area was part of what they discovered “Late Jurassic Chihuahua Trough” a tropical region that “may have been comparable to the Gulf of California today in terms of both geological setting and biological diversity.”

Like the modern Gulf of California, the late Jurassic Chihuahua Trough would have been home to a plethora of aquatic dinosaurs that can still be found, they wrote in their new study, because the Trough supported “tropical and temperate species from coastal and oceanic environments.’