Harvester ants are very industrious. They build mounds that last for decades, protecting them with a half-inch-thick layer of small rocks about the size of beads, then clear the surrounding area of vegetation by as much as 30 feet. But in gathering up all those rocks, they also collect tiny fossils and archaeological artifacts.
Don’t underestimate these little guys. Researchers examined 19 of these mounds in Nebraska, and were surprised to find more than 6,000 microfossils—each no more than a few millimeters wide—from ancient mammals. These included small teeth and jaw fragments that led to the identification of nine new species of rodents and a new species of insect-eating, shrew-like animal. In addition, these fossils also fill in the biological gaps of known creatures, revealing totally new types of teeth from several extinct rodents.
Studying these fossils also gives a better understanding of what was happening in North America about 34 million years ago. This era was the end of the Eocene and the beginning of the Oligocene epochs, an important period in evolution. During this time, the planet went into a prolonged cooling period, which caused the extinction of some species and rearranged ecosystems across the planet.
So rather than being pests, harvester ants are our important scientific partners. Now, if they would just start collecting larger rocks…
Taken from “Fossil-finding Ants Amass Huge Haul of Ancient Creatures ” by Michael Greshko (https://www.nationalgeographic.com/science/article/fossil-finding-ants-amass-huge-haul-of-ancient-creatures?).