Imaging of a 113-million-year-old ant fossil reveals complex, specialized mandibles, showing advanced predatory traits much earlier in ant evolution than expected.
A 113-million-year-old hell ant that once inhabited northeastern Brazil is now recognized as the oldest ant specimen ever discovered, according to a study published in the journal Current Biology.
Preserved in limestone, the ant belongs to Haidomyrmecinae, an extinct subfamily that lived only during the Cretaceous period. These ants were equipped with specialized, scythe-like jaws likely used to pin or impale their prey.
“Our team has discovered a new fossil ant species representing the earliest undisputable geological record of ants,” said Anderson Lepeco of the Museu de Zoologia da Universidade de São Paulo in Brazil. “What makes this discovery particularly interesting is that it belongs to the extinct ‘hell ant,’ known for their bizarre predatory adaptations. Despite being part of an ancient lineage, this species already displayed highly specialized anatomical features, suggesting unique hunting behaviors.”
Researchers say the fossil challenges existing ideas about ant evolution and their historical distribution. Previously, the oldest known ant fossils were found in France and Burma and preserved in amber. The discovery of a hell ant in Brazil indicates that ants had already spread across different regions and evolved into diverse forms much earlier than scientists had believed.
Limestone discovery confirms early ant diversity
“Even though there have been hell ants described from amber, this was the first time we could visualize this in a rock fossil,” said Lepeco.
Lepeco and his team discovered the “remarkably well-preserved” ant specimen while systematically examining one of the world’s largest collections of fossil insects from the Crato Formation, a deposit renowned for its exceptional fossil preservation. The collection is housed at the Museu de Zoologia da Universidade de São Paulo.
“When I encountered this extraordinary specimen, we immediately recognized its significance, not only as a new species but as potentially the definitive evidence of ants in the Crato Formation,” said Lepeco. “This finding highlights the importance of thorough examination of existing collections—private or in museums—and brings a spotlight to Brazilian paleontology and the underexplored fossil insect fauna of the country.”
Fossil imaging reveals unique feeding traits
Micro-computed tomography imaging—a 3D imaging technique that uses X-rays to view the inside of an object, or ant in this case—showed that the newly discovered ant was closely related to hell ants previously known only from specimens preserved in Burmese amber—a type of amber found in Myanmar. The finding shows that the ants were widely distributed across the globe and must have crossed Cretaceous landmasses repeatedly, say the authors. But what astonished them most was the hell ant’s specialized features.
“While we expected to find hell ant features, we were shocked by the characteristics of its feeding apparatus,” said Lepeco. Unlike modern ants with laterally moving mandibles, this species possessed mandibles that ran forward parallel to the head and facial projection anterior to the eyes, the researchers noted.
“Finding such an anatomically specialized ant from 113 million years ago challenges our assumptions about how quickly these insects developed complex adaptations. The intricate morphology suggests that even these earliest ants had already evolved sophisticated predatory strategies significantly different from their modern counterparts.”
The discovery of this new ant specimen raises broader questions about the evolutionary pressures that led to the hell ant’s unique adaptations, say the researchers. With advanced imaging tools, it’s now possible to examine such fossil specimens in much greater detail than ever before.
Reference: “A hell ant from the Lower Cretaceous of Brazil” by Anderson Lepeco, Odair M. Meira, Diego M. Matielo, Carlos R.F. Brandão and Gabriela P. Camacho, 24 April 2025, Current Biology.
DOI: 10.1016/j.cub.2025.03.023
This research was supported by funding from FAPESP.
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