What Moretti pulled from that underground stream in Comal County turned out to be far more unusual than a typical Ice Age bone haul. Among the finds were shell fragments from a giant tortoise and armor plates from a pampathere, an armadillo relative roughly the size of a lion. Neither species had ever been documented in Central Texas before. The research was published in the journal Quaternary Research<\/a>.<\/p>\n Texas and the Edwards Plateau with relevant Late Pleistocene sites indicated. (CREDIT: Quaternary Research)<\/p>\n The cave itself sits beneath private land and carries an active underground stream connected to the Trinity Aquifer system. Moretti and co-author John Young, a local caver, made six trips into the cave between March 2023 and November 2024, dividing the stream passage into 21 sampling zones and collecting fossils by hand from the underwater gravel. No excavation needed. The bones were simply lying there.<\/p>\n A Different Kind of Fossil Site<\/p>\n Water caves are common throughout the karst limestone of the Edwards Plateau, which stretches across much of Central Texas. But despite nearly a century of paleontology work in the region, no one had formally studied the fossils sitting in these underground rivers. Water caves are, in some ways, difficult places to do science. The stream level fluctuates with rainfall. Access requires rappelling into sinkholes. And without stable sediment layers, pinning down the age of the bones is genuinely hard.<\/p>\n Moretti estimates the Bender\u2019s Cave fossils are late Pleistocene<\/a>, likely older than 20,000 years. The more intriguing possibility, which he describes carefully, is that they could date to the last interglacial period, a warm interval that peaked around 125,000 years ago and is known in geological terms as Marine Isotope Stage 5. If so, they would fill a conspicuous gap.<\/p>\n \u201cThis site is showing us something different, and that\u2019s really important because of all the work that\u2019s been done in this region,\u201d Moretti said. \u201cIf it is interglacial in age, it\u2019s a new window into the past and into a landscape, environment, and animal community that we haven\u2019t observed in this part of Texas before.\u201d<\/p>\n Stream passage in Bender\u2019s Cave. (A) Low ceilings and shallow water; (B) collecting fossils underwater in one of two large rooms; (C) snorkel survey in deeper water; note the mud coating on the ceiling and walls (All units are in millimeters). (CREDIT: Quaternary Research)<\/p>\n Other notable finds from the cave include claws from a Jefferson\u2019s ground sloth, teeth from saber-tooth cats, bones from camels, horses, bison, and mammoths<\/a>, and fragments from mastodons. The bones are polished, reddish-brown, and heavily mineralized, suggesting they entered the cave roughly together, swept in through sinkholes during flooding events. Two bone samples submitted for radiocarbon dating lacked usable collagen, and the one date that came back was almost certainly contaminated by carbonate-rich groundwater.<\/p>\n What the Animals Suggest<\/p>\n The real argument for an interglacial age comes from the animals themselves. The pampathere and giant tortoise needed warm temperatures to survive. The ground sloth and mastodon<\/a> were forest browsers, dependent on woody vegetation. Central Texas during the last glacial maximum, roughly 20,000 years ago, was an open grassland in a cool, relatively dry climate. There would have been little room for them.<\/p>\n During warmer interglacial periods, the region may have supported forests, a warmer climate, and the animals that came with both. That\u2019s exactly the combination seen at coastal and north Texas sites, like Ingleside and Moore Pit, which are interpreted as interglacial in age and contain the same four species found at Bender\u2019s Cave.<\/p>\n To put numbers behind this intuition, Moretti ran a hierarchical cluster analysis comparing the fossil composition at 43 Texas sites from the Late Pleistocene. The algorithm grouped Bender\u2019s Cave with sites from the last interglacial, not with the younger Central Texas caves that share its geography.<\/p>\n Fossils of Megalonyx jeffersonii and Holmesina septentrionalis. (CREDIT: Quaternary Research)<\/p>\n David Ledesma, an assistant professor at St. Edward\u2019s University who was not part of the study, said the results were genuinely surprising. \u201cSome of the fossils that John has come across are species that we didn\u2019t think would occur in this part of Texas,\u201d he said. \u201cThat we\u2019re still learning new things and finding new things is quite exciting.\u201d<\/p>\n Practical Implications<\/p>\n The limitations of the study are real. The fossils in a cave stream are not sealed in sediment like those in a dry cave deposit. They can mix across time, and without reliable radiometric dates, the ages remain uncertain. Moretti acknowledges that the assemblage could represent multiple time intervals rather than a single snapshot. New dating approaches, including uranium-thorium dating of speleothems and coupled uranium-series and electron spin resonance dating of fossil teeth<\/a>, are underway.<\/p>\n But even before those results come in, the cave matters. If the four novel species really did live in Central Texas during a warm interglacial period, the regional fossil record has a significant gap in it, one that existing sites were unable to detect. That has direct consequences for how scientists understand the habitat diversity of Pleistocene Texas, and possibly for how they model the relationship between climate and large mammal distributions more broadly.<\/p>\n It also has a more immediate message for land stewardship. Most caves in Texas sit on private land. Moretti was only able to conduct this research because local landowners gave access and donated the fossils to the Jackson School Museum.<\/p>\n \u201cThese connections and partnerships make possible a lot of the natural science that gets done in Texas,\u201d he said. \u201cIt takes contributions from everyone, not just scientists at universities, to learn about the natural world we live in and depend on.\u201d<\/p>\n Research findings are available online in the journal Quaternary Research<\/a>.<\/p>\n The original story \u201cLion-sized armadillo, ancient tortoises: Ice age creatures discovered in Central Texas<\/a>\u201d is published in The Brighter Side of News.<\/p>\n Related Stories<\/p>\n![\"Texas](\"https:\/\/www.newsbeep.com\/us-tx\/wp-content\/uploads\/2026\/03\/afdd3abab502ecf171b59784a59e4055.jpeg\"\/)
<\/p>\n![\"Stream](\"https:\/\/www.newsbeep.com\/us-tx\/wp-content\/uploads\/2026\/03\/f379999a02eabc7bc901d946decc5e0c.jpeg\"\/)
<\/p>\n![\"Fossils](\"https:\/\/www.newsbeep.com\/us-tx\/wp-content\/uploads\/2026\/03\/32e42de09580f575891c74c0219a3d8c.jpeg\"\/)
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