Researchers report fossil evidence that suggests ancient bees nested inside empty tooth sockets in mammal jaw bones about 20,000 years ago. The discovery comes from a cave site where bird activity—described as owls scattering bones across the cave floor—left small bone elements in place long enough to be used by bees. The nests were found in association with fossilized animal jaws and are interpreted as trace fossils, indicating the locations where bees laid eggs rather than evidence of the bees themselves. Scientists describe the behavior as solitary-bee nesting that repurposes existing cavities for reproduction, using the tooth sockets of bones as protected nursery spaces. The findings are presented as the first known evidence of bees nesting inside animal bones, expanding what researchers consider possible in bee nesting strategies over evolutionary time. The authors note that similar cases could exist in other fossil collections, but further study is needed to confirm how widespread the behavior was and which bee lineages were involved.