Novel occurrences of Late Pleistocene megafauna from Bender’s Cave on the Edwards Plateau of Texas may include evidence of the last interglacial

Abstract Bender’s Cave on the Edwards Plateau of Texas contains evidence of Late Pleistocene biodiversity that contrasts with the record from 17 regional sites dating to the last glacial interval, Marine Isotope Stage 2 (MIS 2). Bender’s Cave is a groundwater conduit system with an underground stream. Fossils occur in the cave primarily as an underwater lag assemblage and represent taxa that are typical of the Rancholabrean Land Mammal Age and common to central Texas (e.g., Bison, Mammuthus, Camelops ). Megalonyx jeffersonii and Mammutidae also occur in Bender’s Cave but are rare elsewhere in the region. Other fossils provide the first regional records of Holmesina septentrionalis and a species of giant Hesperotestudo . The paleoecology of those novel taxa is inconsistent with regional paleoenvironmental proxies for MIS 2, which document a relatively open, dry grassland and cool climate. The novel composition of the assemblage may be the product of sample bias, and the fossils may be vastly time-averaged. However, the identified taxa frequently co-occur in other Texas sites interpreted as dating to interstadial/interglacial intervals of the late Pleistocene (i.e., MIS 3 or MIS 5), suggesting that fossils in Bender’s Cave may also date to one of those earlier warm periods.