Imagine John Moretti wearing a wetsuit and goggles as he moves through the chilly, dark water of Bender’s Cave, reaching down through the current to retrieve a bone from the cave floor because there were bones all over the place, not because he just happened to see one. That’s the detail that keeps coming up in his descriptions of the discovery: the sheer, nearly overwhelming quantity of what the cave had amassed and preserved, rather than the one exceptional specimen that grabs attention and indicates a find. “There were fossils everywhere, just everywhere, in a way that I haven’t seen in any other cave,” he stated. “It was just bones all over the floor.” Moretti, a paleontologist who just finished his doctorate at the Jackson School of Geosciences at the University of Texas at Austin, had come to carry out the first official paleontological investigation of a water cave in Texas. For years, cavers had anecdotally reported that Bender’s Cave, which is situated on private property in Comal County close to San Antonio, was rich in fossils. But what he discovered went beyond what the rumors had suggested.
| Field | Details |
|---|---|
| Topic | Fossilized Ice Age Megafauna Discovered in Bender’s Cave, Central Texas |
| Discovery Location | Bender’s Cave, Comal County, Texas (near San Antonio) — located on private property |
| Lead Researcher | John Moretti, Paleontologist — University of Texas at Austin (Jackson School of Geosciences) |
| Published Study | Quaternary Research journal |
| Exploration Period | March 2023 – November 2024 (21 distinct survey areas) |
| Estimated Age of Fossils | ~100,000 years ago (last interglacial period) — dating ongoing |
| Key Fossils Found | Mastodon, giant ground sloth (Megalonyx), pampathere, ancient camels, giant tortoise |
| Pampathere Facts | South American origin; migrated north ~2.7 million years ago; weighed up to 440 lbs; plant-based diet; extinct ~12,000 years ago |
| Exploration Method | Snorkeling — no excavation; specimens collected directly from cave floor |
| Preservation Mechanism | Flooding and sinkhole deposits transported and sealed bones in anaerobic, oxygen-poor water environment |
| Historical Context | Most Central Texas finds relate to colder ice age phases; this site documents a warmer interglacial interval not previously observed in the region |
| Cave Function | Water cave — conduit for underground stream; part of Central Texas groundwater system |
| Preservation Science | Rapid burial by floodwaters in low-oxygen environment prevents oxidation and decay; flood events act as a “capping” stratigraphic layer |
| Broader Regional Context | Lower Pecos Canyonlands contain 12,000+ years of environmental history in layered flood sediments (NPS records) |
| Reference 1 | The Daily Galaxy — Scientists Dive Into a Flooded Texas Cave and Discover a Massive Prehistoric Graveyard |
| Reference 2 | National Park Service — Amistad NRA Cultural Resources Study: 12,000 Years of Environmental History |
The location contains fossilized remains of animals, some of which are remarkable, that have never before been found in central Texas. The pampathere, a heavily armored relative of contemporary armadillos, originated in South America and migrated northward approximately 2.7 million years ago following the creation of the Panama Isthmus. The teeth and jaw structure of the pampathere were designed for coarse vegetation, a plant-eater in a landscape that no longer exists, in contrast to its smaller modern cousins, which will eat nearly anything. It went extinct about 12,000 years ago and weighed up to 440 pounds. One centimeter-long scale from its shell-like covering was discovered in the cave, sufficient to positively identify it. The remains of mastodons, giant ground sloths of the genus Megalonyx, ancient camels, and giant tortoises are also present; these animals once lived in the Texas Hill Country during a warmer period of the last ice age, leaving a record that scientists are only now starting to decipher.
It is no accident that the cave serves as a time capsule. As a water cave, Bender’s Cave is a conduit for a subterranean stream that is a component of the extensive groundwater system that runs through central Texas. During erosion and flooding events thousands of years ago, bones entered it through sinkholes; high-energy water carried them in, deposited them in the dark, and left them mostly undisturbed. It turns out that the conditions that render water caves unsuitable for other types of disturbance are precisely what make them exceptionally good at preservation. The biological processes that would normally break down organic material are slowed down in submerged, low-oxygen environments. The flooding that brought the bones in also kept them isolated from the outside world, enveloping them in an anaerobic stillness that preserved them for a very long time. What the surface would have eventually destroyed was preserved in the cave.
The region’s paleontological and archaeological records repeatedly show this dynamic—a catastrophic water event as a preservation mechanism. Further west, in the Lower Pecos Canyonlands, records from the National Park Service detail how the plant material, animal remains, and flood sequences preserved in the region’s rock shelters and cave systems can be used to reconstruct over 12,000 years of environmental history. Stratigraphic layers, which are discrete bands of sediment that divide one era’s deposits from the next, were produced by the floods that periodically passed through those environments during the late Pleistocene and Holocene. This allowed researchers to track a change in climate from what was once a cooler, wetter parkland savannah to the more arid desert environment that currently defines the area. The flood sequences are the record itself, not merely its context.
Bender’s Cave is especially important because of the age of its contents. According to Moretti and his colleagues, the fossils most likely date back to the last interglacial period, which occurred about 100,000 years ago. Dating is still being done using time-appropriate radiocarbon and uranium-thorium techniques. There is a significant knowledge gap regarding the landscape’s appearance during warmer interglacial periods because the majority of earlier paleontological discoveries in central Texas pertain to the colder stages of the ice age. In a way that no other site in the area currently does, Bender’s Cave starts to fill that gap if the dating is accurate. As noted by St. Edward’s University assistant professor David Ledesma, who was not involved in the study: “Some of the fossils that John has discovered are species that we didn’t think would occur in this part of Texas.” It’s exciting that we’re constantly discovering and learning new things.”
The investigation that yielded these results was carried out in 21 different locations throughout the cave between March 2023 and November 2024. By the standards of most paleontological fieldwork, the methodology was unconventional: there was no sediment screening, no excavation, and no meticulous brushwork on exposed surfaces. Rather, scientists simply reached into the water to gather specimens from the floor while snorkeling through the cave’s passageways. The study, which was published in Quaternary Research, explains how the bones were carried into and concentrated in the cave’s lower chambers by the water levels that fluctuated over millennia due to rainfall, flooding, and sinkhole deposits. With every dive, new specimens emerge from a floor that is still covered by the water that preserved them.
Bender’s Cave is a satisfying paradox. In popular perception, flooding is a force that disperses, erodes, and destroys, making it the enemy of preservation. A more nuanced picture is revealed by the evidence from central Texas. These bones were deposited in an area that was inaccessible to decay due to flooding. The stratigraphic clarity that allows researchers to date and interpret their findings was created by flooding, which divided one chapter of the local environment from the next. In a different register, the disaster that put an end to the pampathere’s world was what allowed John Moretti to reach down through icy cave water twelve thousand years later and retrieve the proof that it ever existed. That’s the kind of irony that usually builds up in the shadows, waiting to be discovered by someone wearing a wetsuit and goggles.
