A remarkable discovery has been made in Japan, where an extremely rare fossil sat unidentified for decades in the Museum of Unique Insect Fossils. Discovered in 1988 in Hyogo Prefecture, this fossil has now been confirmed to belong to a previously unknown extinct species. The study, published in Paleontological Research, sheds new light on the fossil’s significance, providing clues about its evolution and distribution during the Early Pleistocene epoch.
Rising to an impressive size and possessing remarkable features, this extinct species challenges previous assumptions about its lineage and the environmental conditions it lived in.
The Discovery of Tacola kamitanii
For over three decades, the fossil of Tacola kamitanii remained largely overlooked, sitting unidentified in the museum’s collection. However, recent efforts have brought the specimen to the forefront of paleontological research, confirming it as a previously unknown species. The butterfly’s wingspan is described as “remarkably large”, measuring almost 3.5 inches (approximately 8.8 cm), a feature that stands out among known butterfly species from the era.
According to the study published in the Paleontological Research journal, Tacola kamitanii is the first butterfly fossil identified from the Early Pleistocene epoch. “Butterfly fossils are extremely rare,” the researchers noted in the study, explaining the difficulty of preserving these delicate creatures over millions of years. They further mentioned, “Butterfly bodies and wings are fragile and buoyant, making them less likely to be preserved as fossils than other insect groups.”
The Rare Butterfly Fossil and Its Significance
The Tacola kamitanii fossil is considered particularly significant because it represents the first named fossil from the Limenitidini subfamily of butterflies, a group that includes living species like viceroys and admirals. The fossil’s identification suggests that this group of butterflies may have been more widespread than previously thought, with its reach extending across Southeast Asia and East Asia during the Late Pliocene to Early Pleistocene.
The fossil is believed to be from a female butterfly, as indicated by its large size and “very thick” abdomen, which is characteristic of females in many butterfly species. This discovery provides an opportunity to study the evolutionary traits and physical differences between genders in ancient butterfly species, something rarely possible with fossilized specimens.
Reconstruction of Tacola Kamitanii (Photo Credit: Hiroaki Aiba, Yui Takahashi and Kotaro Saito (2025))
Climate and Habitat of Tacola kamitanii
Researchers suggest that the Tacola kamitanii butterfly lived in regions that experienced warm to mild climates, particularly during the transition period from the Late Pliocene to the Early Pleistocene. As the global climate shifted during this time, so too did the environment of the Japanese islands, which saw a movement from warmer temperatures to cooler, more temperate conditions.
The Tacola kamitanii fossil offers clues about how ancient butterfly species adapted to these environmental changes. It is believed that the distribution of the genus Tacola was not limited to Japan, but spread widely across Southeast Asia and East Asia during the Late Pliocene to Early Pleistocene. This suggests that the Tacola genus had a much broader ecological range than previously assumed, expanding researchers’ understanding of how these butterflies interacted with their environment.