By the time the butterflies came, the world was already healing.
Roughly 236 million years ago, in the scarred aftermath of Earth’s greatest extinction event, a hippo-sized herbivore ambled through what is now northwestern Argentina. The creature—a dicynodont—was no butterfly. But it may have been the unwitting courier of one. When it defecated, it left behind a microscopic legacy in a “communal latrine”.
Inside that coprolite (a fossilized piece of dung) paleontologists have discovered the oldest physical evidence of Lepidoptera, the group that includes moths and butterflies. Microscopic scales, just 200 microns long, were found embedded in the ancient dung. Their structure was unmistakable.
Talk About a Butterfly Effect
For decades, evolutionary biologists have believed that butterflies and moths first emerged around 241 million years ago. Molecular clocks—a tool that uses genetic data to estimate evolutionary timing—suggested this timeline. But hard evidence remained elusive.
Until now, the oldest known lepidopteran fossils dated back only to 201 million years ago, leaving a frustrating 40-million-year gap in the record. The new discovery from Argentina’s Talampaya National Park slices through that gap with precision.
The coprolite, preserved in the Chañares Formation, is dated to the first stage of the Triassic period, about 236 million years ago. It was found in a prehistoric communal latrine, a sort of Triassic public restroom used repeatedly by dicynodonts. These herbivores were megaherbivorous vertebrates that thrived after the end-Permian mass extinction, which wiped out around 90% of life on Earth.
Inside the dung, researchers found lepidopteran wing scales so well-preserved that they were able to identify a new species: Ampatiri eloisae.
The Butterfly That Fed on Trees, Not Flowers
Despite the species’ age, it likely belonged to a subgroup called Glossata—the modern lineage of moths and butterflies that have a feeding tube called a proboscis. But flowers first appeared in the Cretaceous, so what could a butterfly sip?
Conifers and cycads, dominant plants at the time, secreted sugary droplets for reproduction—pollination drops. Researchers believe that Ampatiri evolved to feed on these drops, long before the first flowers appeared nearly 100 million years later.
By analyzing the scales’ features, the team estimated that proboscis-bearing lepidopterans may have evolved between 260 and 244 million years ago—right after the end-Permian apocalypse. This timing would align with the broader resurgence of life during the Triassic, when insect groups like flies, wasps, and now moths underwent massive diversification.
The new species’ name, Ampatiri eloisae, carries rich meaning. In the Indigenous Calchaquí language of the region, ámpa means butterfly and tiri means ancient. The second part of the name honors Eloísa Argañaraz, a young doctoral student who helped discover the coprolites and passed away from brain cancer soon after.
In the Calchaquí worldview, when a warrior dies, their soul becomes a butterfly.
The Long Flight of Lepidoptera
For scientists, the find offers more than poetic resonance. It provides the first physical evidence of lepidopterans from the Triassic and helps reconcile the long-standing mismatch between fossil evidence and molecular estimates.
“This finding helps reconcile the long-standing gap between the molecular clock estimates… and the comparatively younger fossil record,” Matteo Montagna, an entomologist at the University of Naples Federico II who was not involved in the study, told Science. “Ancient dung, modern insights.”
Utrecht University paleontologist Bas van de Schootbrugge, who co-discovered the previous oldest butterfly wing scales in Germany, called the find “fascinating.” However, he cautioned that without a full body fossil, it’s hard to tell whether the scales came from one individual or multiple.
Still, he holds out hope: “Although it might be like looking for a needle in a haystack, I believe we’ll see more.”
The butterfly in the dung is almost definitely not the first butterfly ever. It may not even be close. But it is the earliest we’ve ever seen—a hint of delicate life in a world still recovering from fire and flood.
The discovery affirms that even in the most unassuming places, like ancient excrement, evolution leaves its trace.
