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Fossilized hackberry (Celtis) seeds were found within the shells of two Stylemys individuals excavated from Oligocene sediments from South Dakota. The presence of in situ skeletal elements indicates that the tortoises were buried without extensive disarticulation. Abiotic transport of the seeds into the carcasses is unlikely given the anatomically correct placement of both skeletal elements and seeds and the comparative settling velocities of the encasing sediment versus modern Celtis seeds. Ecological evidence from modern Celtis and Stylemys analogues suggests that tortoises are commonly seed dispersal agents. The fossils are therefore interpreted as enterolites, providing the oldest reliable evidence of tortoise frugivory.