Researchers report that the earliest known fossils of pollen-laden insects belong to ground-dwellers similar to earwigs that lived in what is now Russia about 280 million years ago. Their discovery pushes back the fossil record of insects that transport pollen from one plant to another, a key aspect of modern pollination, by about 120 million years.
According to Oleksandr Khramov, a paleoentomologist from the Borysyak Paleontological Institute in Moscow, these insects are from The pollen-eating Tillyardembia, first described in 1937, were usually about 1.5 centimeters in length. The fragile wings probably kept the creatures mostly on the forest floor, he says, leaving them to climb trees to find and consume their pollen.
Recently, Khramov and his colleagues carefully studied 425 fossils Tillyardembia in the collection of the institute. The team reported on February 28 in journal Biology Letters , that six had pollen grains trapped on their heads, legs, chest, or abdomen. Such a small proportion is not surprising, says Khramov, since the fossils were preserved in what was originally a fine-grained sediment. Early stages of fossilization in such material tend to wash away pollen from insect remains.
The team found that the pollen-laden insects had only a few types of pollen, suggesting that the animals were very selective about the types of trees they visited. “This kind of specialization corresponds to potential pollinators,” says Michael Engel, a paleoentomologist at the University of Kansas in Lawrence who was not involved in the study. “There is probably a huge amount of such specialization that took place even before Tilyardembia but we have no evidence of this yet.”
Further study of these fossils may reveal whether the Tillyardombius evolved special pollen-trapping hairs or other similar structures on their bodies or heads, says Conrad Labandeira, a paleoecologist at the National Museum of Natural History in Washington, D.C., who was also not part of the study. . It would also be interesting, he says, to see if something in the pollen helped it stick to insects. For example, if pollen grains had a structure that allowed them to stick together more easily, then those same features could help them attach, like Velcro, to any hairy structures on the bodies of insects.