A newly discovered fossil from Australia is rewriting what scientists know about the origins of non-biting midges—tiny insects that thrive near lakes and rivers.
The fossil, estimated to be around 151 million years old, dates back to the Jurassic period and represents the oldest known member of the Chironomidae family ever found in the Southern Hemisphere.
This remarkable find suggests that these freshwater insects may have first evolved in the ancient southern supercontinent known as Gondwana.
The discovery, led by an international research team from the Doñana Biological Station (EBD-CSIC) in Spain, together with experts from the Australian Museum Research Institute, the University of New South Wales, the University of Munich, and Massey University in New Zealand, was published in Gondwana Research.
The fossil was unearthed at the Talbragar Fish Beds in New South Wales, one of Australia’s most famous Jurassic fossil sites.
The new species has been named Telmatomyia talbragarica, which translates to “fly from the stagnant waters.” The name reflects the calm, lake-like environment where the insect lived.
The site’s sediments indicate a freshwater habitat—an important detail because the fossil displays a unique adaptation that was previously believed to occur only in marine species.
The researchers discovered that both the pupal and adult stages of the insect featured a small terminal disk, a structure that likely allowed the insect to anchor itself to rocks or other surfaces underwater.
This adaptation shows a surprising flexibility, or phenotypic plasticity, in how these ancient insects were able to survive in different environments.
Dr. Viktor Baranov, the study’s lead author, explains that the find changes the long-held view of where these insects originated.
For decades, scientists believed that the subfamily Podonominae, which includes these non-biting midges, evolved in the Northern Hemisphere—on the ancient landmass known as Laurasia—before spreading south.
However, the fossil from Talbragar supports a very different idea: that these insects first evolved in Gondwana and only later dispersed to other parts of the world.
Today, members of the Podonominae subfamily are found mostly in the Southern Hemisphere, including South America, Australia, South Africa, and New Zealand.
Their fragmented global distribution fits a pattern known as vicariance, in which species become separated by the breakup of continents and evolve independently.
This supports a hypothesis proposed by Swedish entomologist Lars Brundin in 1966—that the ancestors of these midges were divided when Gondwana split apart millions of years ago.
Despite this exciting discovery, much remains unknown. Fossils of freshwater insects are rare, and most of the known Podonominae fossils come from the Northern Hemisphere. Only two others have been identified from the south—one from Australia’s Eocene epoch and another from India’s Paleocene epoch.
“There’s a strong bias in fossil research toward the Northern Hemisphere,” says Dr. Matthew McCurry from the Australian Museum and UNSW. “That means we often make incorrect assumptions about where species first evolved.”
Professor Steve Trewick from Massey University adds that these tiny fossils can have an outsized impact: “Delicate insect fossils like this one help us understand how Southern Hemisphere ecosystems formed and changed over time.”
Future studies combining fossil evidence with genetic data could reveal whether these insects spread passively—by drifting on air or water currents—or actively migrated as Gondwana’s landmasses drifted apart.
Ultimately, this ancient fly from Australia provides more than just a glimpse into a long-lost world—it helps scientists piece together the deep evolutionary story of Earth’s biodiversity.
Source: KSR.
