Bender's Cave Ice Age Giants Rewrite Edwards Plateau
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- Dr. John Moretti of the University of Texas and local caver John Young conducted the first scientific investigation of Bender's Cave, recovering Pleistocene megafauna including mammoths, bison, horse, and Camelops camel alongside two unexpected species: a giant tortoise (Hesperotestudo) and a pampathere (Holmesina septentrionalis).
- Hesperotestudo and Holmesina septentrionalis are warm-adapted species that contradict existing climate records for the Edwards Plateau, which characterize the region as dry, cool, open grassland — habitat the researchers say was unsuitable for tortoises and pampatheres.
- Bender's Cave is a water cave with active underground streams; some fossils required masks and snorkels to retrieve from passages accessed via a sinkhole roughly 11 meters below the surface.
- Hierarchical cluster analysis comparing the Bender's Cave assemblage to other late Pleistocene Texas sites suggests the fossils likely date to Marine Isotope Stage 5 (~71,000–130,000 years ago), the last interglacial — making it one of only a handful of Texas sites from that period.
- An attempted radiocarbon date of 17,330–17,030 cal BP was likely skewed by geochemical contamination, and MIS 5 sits beyond the reach of radiocarbon dating; the team plans U-Th dating of speleothems and U-series/electron spin resonance dating of mammal teeth to refine the age.
- Moretti reports that multiple other Texas Hill Country water caves show similar fossil preservation patterns and novel taxa, meaning Bender's Cave could serve as a template for interpreting those assemblages across the Edwards Plateau.
Why it matters: The presence of warm-adapted tortoises and pampatheres on the Edwards Plateau directly contradicts the region's established dry-grassland climate model. If the team's planned U-series and ESR dating confirms an MIS 5 age, Bender's Cave joins a tiny number of Texas sites anchoring faunal records for the last interglacial — expanding the known northern range of species like Hesperotestudo and Holmesina and reframing central Texas as once-forested rather than always-grassland.
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