A hidden source of Ice Age history has turned up at a water-filled cave in Texas, where a paleontologist discovered dozens of ancient fossils. Water caves throughout the state, home to active underground rivers and streams, have been touted as fossil treasure troves, but they haven’t been thoroughly explored yet for their paleontological potential — until now.
A new study published in Quaternary Research details an unprecedented survey of fossilized remains in a Texas water cave, identifying fossils that have never been seen before in central Texas. Among the fossils found are ones from a giant tortoise and an armadillo relative that was as big as a lion; these fossils, and many others, may date back to a warm period in Texas around 100,000 years ago.
“This site is showing us something different, and that’s really important because of all the work that’s been done in this region,” paleontologist John Moretti of the University of Texas at Austin said in a press release. “If it is interglacial in age, it’s a new window into the past and into a landscape, environment, and animal community that we haven’t observed in this part of Texas before.”
Texas Caves and Fossil Finds
Regional water caves in central Texas contain the remains of many Pleistocene vertebrates, but according to the new study, these fossils are poorly documented. The caves’ fossil-rich reputation has come from anecdotal descriptions by cavers in the state.
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Giant ground sloth claw fossil.
(Image Credit: John Moretti/The University of Texas at Austin)
However, Moretti saw firsthand how this reputation came to be. As he explored an underground stream at Bender’s Cave, a water cave on private property, Moretti went snorkeling for fossils and encountered a staggering number of fossils.
“There were fossils everywhere, just everywhere, in a way that I haven’t seen in any other cave,” said Moretti in the statement. “It was just bones all over the floor.”
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Extinct Megafauna Galore
Moretti and study co-author John Young, a local caver, made six trips to Bender’s Cave from March 2023 to November 2024, gathering fossils from 21 different zones of the cave. During their trips, the depth of the stream from which they collected samples was often only a few feet deep. The fossils were easy to obtain, as well, since there was no need for intensive excavations — all they had to do was pluck the samples from the stream bed.
Illustration of a sloth and armadillo from the Last Ice Age.
(Image Credit: Adapted from artwork by Jaime Chirinos./CC BY-SA)
The remains at Bender’s Cave, which entered the cave through sinkholes during erosion and flooding events thousands of years ago, include specimens from extinct megafauna that are commonly found in the area, including mammoths and North American camels. Conversely, other remains at the cave, from the Jefferson’s ground sloth (Megalonyx jeffersonii) and proboscideans (the family that includes mastodons), are rarely seen in central Texas.
The new study also established the first regional records of Holmesina septentrionalis, a species of pampathere (an extinct armadillo-like mammal), and a species of giant Hesperotestudo (an extinct genus of tortoise).
A New Look at Ice Age Texas
Moretti believes the fossils at Bender’s Cave may date back to the last interglacial, a stretch of warm climate conditions that took place 100,000 years ago during the last Ice Age. But a lack of geologic material that can be reliably dated in the cave makes it difficult to confirm the fossils’ true age.
The habitat and temperature preferences of the animals that once lived in central Texas provide clues, though. The ground sloth and mastodon lived in forests, and the giant tortoise and pampatheres required warm temperatures to live. The last interglacial fits these preferences, as central Texas might’ve temporarily been more forested during this time (whereas during the cool glacial interval, it would’ve shifted to a sprawling grassland with dry and cold conditions).
Moretti also determined that the Bender’s Cave fossils share similarities with fossils closer to the Dallas area and the Gulf Coast that are from the last interglacial; interestingly, they aren’t as closely related to fossils from the 17 Late Pleistocene sites on the Edwards Plateau, the region where the cave is located.
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Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from a study published in Quaternary Research: Novel occurrences of Late Pleistocene megafauna from Bender’s Cave on the Edwards Plateau of Texas may include evidence of the last interglacial
