Insects rarely survive in fossilized form, but a strange series of events somehow killed and preserved these brooding bees for millenniums.
“The exoskeleton of bees (and insects in general) is made of chitin, a cellulose-like biopolymer that quickly is decomposed after the animal dies,” Mr. Neto de Carvalho wrote in an email.
What bees typically leave are trace fossils or ichnofossils — imprints frozen in time of bodies, abandoned or active nests, or old burrows.
The cocoons that the team discovered were lined and sealed with a silk-like thread produced by the mother bee. This thread was a waterproof, organic polymer — a mixture of material and structural engineering — that had fostered the preservation of the bees inside. Mr. Neto de Carvalho said that this “organic mortar” had protected the cells from the environment, shielding the delicate chitin from bacterial activity and decomposition.
Using X-ray microcomputed tomography, scientists could look inside the brood cells and see the bees’ long antennae, indicating that they were male.Credit…Federico Bernardini/ICTP
The eyes and head of a bee extracted from the sediment.Credit…Andrea Baucon
“The exoskeleton of bees (and insects in general) is made of chitin, a cellulose-like biopolymer that quickly is decomposed after the animal dies,” Mr. Neto de Carvalho wrote in an email.
What bees typically leave are trace fossils or ichnofossils — imprints frozen in time of bodies, abandoned or active nests, or old burrows.
The cocoons that the team discovered were lined and sealed with a silk-like thread produced by the mother bee. This thread was a waterproof, organic polymer — a mixture of material and structural engineering — that had fostered the preservation of the bees inside. Mr. Neto de Carvalho said that this “organic mortar” had protected the cells from the environment, shielding the delicate chitin from bacterial activity and decomposition.
Sealed in their cocoons, the bees mummified, preserving their body shape and distinctive features. The team used X-ray microcomputed tomography — a type of CT scanning that captures detailed images of small things like insects — to examine the mummified bees without destroying the protective cocoons.
“I think what makes this study so cool is that you do have the bee in there and you can see that it’s in the tribe Eucerini, which are the long-horned bees,” said Bryan Danforth, an entomologist at Cornell University who was not involved in the study. “If you look at the CT image, you can see the long antennae, so you know it’s a male.”
Usually, determining what created a fossilized brood cell is tricky. “There are other animals that burrow into the soil that might create a thing that looks like a bee nest,” Dr. Danforth said.
The discovery, he added, is “the first ichnofossil that actually contains the bee inside of it.”
As for what killed the bees, the researchers considered flooding or a prolonged drought that might have limited food supplies. But the pollen stored inside the cells told the team that the bees had plenty of food (meaning they didn’t die by starvation).
Read the rest of the article here: https://www.nytimes.com/2023/