UTEP geology professor Jason W. Ricketts discovered fragments of a Tenontosaurus while mapping at the Indio Mountains Research Station in fall 2023. The material — three tail vertebrae and part of a femur from the Yucca Formation — dates to about 115 million years ago. This find pushes Tenontosaurus' known range roughly 250 miles east of Arizona sites and about 560 miles southwest of previous north-central Texas finds, marking the southernmost North American record. The excavation involved UTEP students and collaborators from the New Mexico Museum of Natural History and Science and Montana State University.
Rare Tenontosaurus Discovery in West Texas Pushes Known Range Farther Southwest
UTEP geology professor Jason W. Ricketts discovered fragments of a Tenontosaurus while mapping at the Indio Mountains Research Station in fall 2023. The material — three tail vertebrae and part of a femur from the Yucca Formation — dates to about 115 million years ago. This find pushes Tenontosaurus' known range roughly 250 miles east of Arizona sites and about 560 miles southwest of previous north-central Texas finds, marking the southernmost North American record. The excavation involved UTEP students and collaborators from the New Mexico Museum of Natural History and Science and Montana State University.
05:40 AM, 11/12/2025Science
Rare Tenontosaurus Fossils Discovered in West Texas
When geology professor Jason W. Ricketts set out to map rock formations at The University of Texas at El Paso's Indio Mountains Research Station, he did not expect to find dinosaur bones. While mapping with a graduate student in the fall of 2023, Ricketts noticed small fragments weathering out of soft shale about 20 miles southwest of Van Horn.
Those fragments have now been identified as part of Tenontosaurus, a plant-eating dinosaur that lived roughly 115 million years ago during the Early Cretaceous. The recovered material includes three tail (caudal) vertebrae and part of a femur, all found in the Yucca Formation — a geologic unit that preserves ancient river and lake (fluvial and lacustrine) deposits.
"We were creating a geologic map of the region, and as we were hiking I noticed some darker rocks that looked different than the rest," Ricketts recalled. "When I picked some of them up, they had a spongy texture like bones do."
Because the fragments were weathering out of the shale, no extensive excavation was required; Ricketts collected the pieces and returned with family members and students to recover additional material. The discovery was described in a study published by the New Mexico Museum of Natural History and Science and involved collaborators from UTEP, the New Mexico Museum of Natural History and Science, and Montana State University.
Significance
Researchers say the fossils expand the known geographic range of Tenontosaurus much farther southwest than previously documented. The new West Texas material lies about 250 miles east of known Tenontosaurus sites in Arizona and roughly 560 miles southwest of earlier finds in north-central Texas, making it the southernmost recorded occurrence of this species in North America. Prior finds had been concentrated in Utah, Wyoming, Montana, Idaho and central/north-central Texas.
Dr. Liz Walsh, interim dean of UTEP's College of Science, noted the discovery as a reminder that "major discoveries can happen when we least expect them." Ricketts hopes the find will encourage more fieldwork in the region: "This discovery shows there's still so much to learn about our region's prehistoric past. It's a privilege to contribute even a small piece to that bigger story."
What Comes Next
Researchers will continue analyzing the material and the surrounding stratigraphy to better understand the local ecosystem and how Tenontosaurus fit into it. The discovery highlights how targeted geological fieldwork can yield unexpected paleontological insights and underscores the paleobiogeographic complexity of Early Cretaceous North America.