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236-million-year-old Triassic fossil reveals earliest known butterfly, moth scales
Paleontologists associated with different institutions in Argentina, along with a scientist from the U.K., have identified specks of scales from lepidopterans—a family of winged insects including several species of butterflies and moths—in samples of dung recovered from an excavation site at Talampaya National Park, located in the Argentina's western La Rioja Province.
Digging at the national park began in 2011, revealing that the area had once served as a communal latrine used by many animals, including large plant-eaters, who returned regularly to urinate and defecate.
Researchers collected dung samples from the Talampaya site and sent them to different institutions for analysis. One of these samples ended up at the Regional Center for Scientific Research and Technology Transfer of La Rioja, where the team behind this new study made the discovery.
Researchers examined the sample using multiple methods and determined it to be around 236 million years old—dating to the middle of the Triassic period and just 16 million years after the end-Permian extinction, which wiped out roughly 90% of Earth's animal species.
Among the contents, paleontologists found tiny scales, each about 200 microns long, which they identified as belonging to a lepidopteran. Previous research has estimated that Lepidoptera first evolved around 241 million years ago. However, until now, the oldest known physical evidence of their existence dated back only to about 201 million years ago.
This left a significant 40 million-year gap between their predicted origin and the earliest fossil record, making it difficult for scientists to confirm when these insects first appeared and how they fit into early ecosystems.
However, the new discovery by the team in Argentina helps fill in a key gap in the evolutionary record of Lepidoptera. It also led to the identification of what may be a previously unknown species, which the researchers have named Ampatiri eloisae.
The researchers noted that, based on the age of the fossil, the newly identified species likely belonged to a subgroup called Glossata—meaning it would have had a proboscis similar to the long, tube-like mouthparts used by modern moths and butterflies to feed on liquids like nectar.
During the Triassic period, forests were made up only of conifers and cycads, as flowering plants had not yet evolved. These nonflowering plants produced sugary droplets to aid pollination—small treats that would have provided an ideal food source for early insects with proboscises.
It is estimated that the proboscis first appeared between 260 and 244 million years ago, soon after the mass extinction event. This suggests that the distinctive feeding structure of butterflies likely developed not from feeding on flowers, but for accessing these ancient nectar-like secretions.
This key adaptation probably enabled early butterflies and moths to thrive by feeding on sugary pollination drops, ultimately setting the foundation for their future interaction with flowering plants, which wouldn't evolve until nearly 100 million years later.
The study of the discovery has been published in the Journal of South American Earth Sciences
