While exploring a cave in central Texas, they unearthed a lost glacial ecosystem, including the remains of a giant tortoise and a lion-sized armadillo, among fossilized groundwater.
In a study published on March 19 in the journal Quaternary Researchthe researchers say that the cave may contain the remains of animals that lived in a relatively warm period during the last ice age. If the findings are confirmed, the site could provide a rare glimpse into an animal community that has been missing from the Texas fossil record.
Moretti and John Young, a local caver, were exploring Bender Cave, near San Antonio, in 2023, when they came across the fossil. The cave is difficult to access and has an underground stream running through it, so it was largely ignored by paleontologists. However, they doubted the fossils were there, since scientific cavers had previously brought their findings, Moretti said.
It was Moretti and Young who found fossils of ice lying in the mud.
“We have backpacks on our waists, and we’re collecting fossils as we go,” Moretti said. Over six trips between 2023 and 2024, Moretti and Young discovered fossils from 21 places in the cave. Among the finds was a claw from a giant sloth (Megalonyx jeffersonii), mammoth teeth, and camel bones (Camelops), has long legs contemporaries modern llamas.
But what really intrigued them was the discovery of fossils of two ice-age beasts: the pampathere (North Holmesina), a large armadillo genus that lived during the middle to late Pleistocene (781,000 to 126,000 years ago); and an extinct species of giant tortoise (Hesperotestudo).
The discovery of these two fossilized animals surprised Moretti and Young because these ice age giants were not known to have lived in this area. For more than a century, researchers have been studying glacial sites in central Texas and building a picture of the area as a dry grassland dominated by grazing animals. According to Moretti, this weather should not be cloudy or cloudy.
Moretti and Young proposed that animal remains were washed into the cave from the top of the pits during floods and deposited on the streambed. If so, the animals may have lived during the warm ice age, about 100,000 years ago, when temperatures rose and animals that prefer light conditions moved into the area, the researchers suggested.
Moretti says that they have not been able to give the correct age of the bones because the collagen proteins that are often used as biomarkers in fossils were completely destroyed by the mineral-rich water. This water also contaminated the fossils, as the bones absorbed carbon and other minerals after being deposited. This means that the analysis can measure this contamination rather than the actual age of the fossils.
To overcome this challenge, the team is now trying to match the calcite crusts that form on the bones after they enter the cave. Although these results will not give exact dates for the fossils, they can put a minimum age for when they were deposited. These days, researchers hope to narrow down whether the remains of the cave represent a warm chapter in “Texas history”.
“We still don’t know everything about the natural world,” Moretti said. “There’s still a lot to discover out there.”
Moretti, JA, & Young, J. (2026). New occurrences of Late Pleistocene megafauna from Bender’s Cave in the Edwards Plateau of Texas may include evidence of the last glaciation. Quaternary Research, 1-27. https://doi.org/10.1017/qua.2025.10071
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