An intriguing study reveals the unique behavior of ancient insects. Dating back to the late Pleistocene, solitary bees used the bones of extinct mammals to build homes for their young. Researchers at the Florida Museum of Natural History are digging through late Quaternary cave sediments in the Dominican Republic hoping to find typical tooth remains in the jaws of extinct rodents, as a study published in the journal Science notes. Royal Society Press. Surprisingly, CT scans revealed that the bones contained complex nests of mud. These structures have been identified as a new trace fossil called Osnidum almontei. This is the first time that bees have been documented using unaltered vertebrate remains as nesting sites. This adaptation highlights how these bees survived in the resource-poor, limestone-rich region of ancient Hispaniola.
Archaeologists expected fossil teeth, but they were honeycombs
In the Dominican Republic’s Pedernales province, researchers discovered something interesting in the Cueva de Mono limestone cave, according to research published in Royal Society Press. When they excavated late Quaternary sediments, they discovered the bones of Plagiodontia araeum, an extinct rodent known as Hutia. The jaws are surprising: the sockets are filled not with surrounding cave sediments but with clearly mineralized biological structures. At first glance, these look like ordinary fossil teeth. However, closer inspection reveals that they are intricate honeycombs crafted within bone cavities.
Scans reveal ancient architect’s hidden blueprints
Researchers discovered a new species, Osnidum almontei, through high-resolution μCT scans. These trace fossils reveal nests with a “Russian doll” or nesting cup structure. Bees cleverly use the rodents’ mandibular alveoli as a protective outer layer for their homes. Inside these shells, they created several stacked barrel-shaped brood chambers. To build these cells, bees collect soil and sediment from nearby areas and use biological secretions to glue them into a ceramic-like material that hardens.
How bees protect their larvae from the dampness of their burrows
Research published in Royal Society Press shows that these solitary bees display high nesting site fidelity. Over many generations, they kept returning to the same fossilized bones. Inside the nest, scientists made some interesting discoveries:
- A smooth hydrophobic (water-resistant) lining on the inner walls of the cells, probably produced by the bee’s Dufour glands, protects the larvae from the dampness of the burrow.
- Clusters of pollen grains were found preserved within the nests, identifying the specific ancient flora collected by the bees to feed their larvae.
- Some rodent jaws contain as many as six different nesting events within a single alveolus.
Bees trade soil for fossil cavities
The researchers found that this behavior developed in response to Hispaniola’s limestone landscape. In these areas, finding soft soil deep enough for regular ground excavation can be a challenge. However, bees take advantage of natural burrows in vertebrate fossils located in the silt floors of caves, providing them with a safe and stable climate-controlled environment. This marks the first time an insect has used the tooth cavity of a fossilized vertebrate as a nesting site.
