The discovery of extinct megafauna, including a colossal tortoise, a massive ground sloth, and a lion-sized relative of the armadillo known as a pampathere, alongside saber-toothed cats, equids, camels, and mastodons, within Bender’s Cave on Texas’s Edwards Plateau, may illuminate a heretofore undocumented warm interval in the region approximately 100,000 years ago.
An artist’s interpretation of mammals that lived during the Ice Age: fossils from similar species of an armadillo-like pampathere (bottom left) and giant ground sloth (background) were among those found in a Texas water cave. Image credit: Jaime Chirinos.
Subterranean water channels, acting as conduits for underground watercourses, function as crucial pathways for groundwater circulation in Central Texas. Cavers have anecdotally reported these formations to be repositories of fossilized remains.
“The sheer abundance of skeletal remains, present in a manner unlike any other cave I have encountered, was astonishing; the cave floor was literally strewn with bones,” remarked John Moretti, a paleontologist affiliated with the University of Texas at Austin.
Situated on private land within Comal County, Bender’s Cave received these osseous specimens through geological processes involving sinkholes, triggered by extensive erosion and inundation that transpired millennia ago, and they have remained undisturbed since.
“There are indications that the cave’s fossil assemblage may originate from the last interglacial period, a warmer epoch that transpired roughly 100,000 years prior,” stated Dr. Moretti.
“Despite decades of comprehensive paleontological investigation in this locale, commencing nearly a century ago, no fossils from this specific temporal span have previously been unearthed in Central Texas.”
“This particular site offers novel insights, which holds significant value given the extensive research already conducted within this geographical area.”
“Should its age be confirmed as interglacial, it presents an unprecedented aperture into a past biome, an ancient landscape, and a faunal community that has remained unobserved in this segment of Texas until now.”
Dr. Moretti, in collaboration with local spelunker John Young, meticulously cataloged fossils from twenty-one distinct strata within Bender’s Cave.
The process of locating these paleontological treasures necessitated navigating the streambed while equipped with diving goggles and a snorkel.
Their retrieval was remarkably straightforward, involving no more than lifting them from the stream’s substrate, obviating the need for any rock excavation.
Among the significant discoveries are skeletal elements belonging to the giant tortoise species Hesperotestudo sp., the enormous ground sloth Megalonyx jeffersonii, the pampathere Holmesina septentrionalis, the scimitar-toothed cat Homotherium serum, in addition to specimens from ancient equids, camelids, and proboscideans.
The uniformly polished, rounded surfaces and consistent rusty-red mineralization of all the discovered fossils suggest a synchronized transport into the cave environment during a single, contemporaneous event.
“This research underscores the fact that even within a thoroughly documented region like Central Texas, significant new discoveries remain possible,” commented Dr. David Ledesma of St. Edward’s University, who was not a participant in this research endeavor.
The scholarly findings reported by the research team are published in the esteemed journal Quaternary Research and can be accessed via the following link: results.
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John A. Moretti & Young, John. 2026. Novel occurrences of Late Pleistocene megafauna from Bender’s Cave on the Edwards Plateau of Texas may include evidence of the last interglacial. Quaternary Research 131: 134-160; doi: 10.1017/qua.2025.10071
