The oldest ant fossil, from the Cretaceous period and preserved in stone, has been discovered in Brazil.
Science Editorial, April 24 (EFEverde).- A 113-million-year-old hell ant found in northeastern Brazil is today the oldest ant specimen in the world. Preserved in limestone, rather than in amber as is usually the case, the ant belongs to the Haidomyrmecinae subfamily, which became extinct in the Cretaceous.
As described by its discoverers in an article published Thursday in the journal Current Biology, the specimen had highly specialized, scythe-like jaws, which it likely used to stab or impale its prey.
"Our team has discovered a new species of fossil ant that represents the oldest undisputed geological record of ants," notes Anderson Lepeco of the Museum of Zoology of the University of São Paulo (Brazil).
The specimen belongs to the extinct "hell ant," known for its strange predatory adaptations. "Despite being part of an ancient lineage, this species already displayed highly specialized anatomical characteristics, suggesting unique hunting behaviors," he notes.
Furthermore, the study notes that the discovery of this ant fossil challenges our understanding of ant evolution and biogeography over time, as previously discovered fossilized ants were discovered in France and Burma and were preserved in amber.
The presence of a hell ant in Brazil demonstrates that ants were already widely distributed and diversified early in their evolution, the study highlights.
"Although hell ants have been described from amber, this was the first time we were able to visualize them in a rock fossil," Lepeco emphasizes.
An extraordinarily well-preserved specimenLepeco and his team discovered the "extraordinarily well-preserved" ant specimen while examining a collection of fossil insects from the Crato Formation—a site renowned for its exceptional preservation—housed at the Museu de Zoologia da Universidade de São Paulo in Brazil.
"When I found this extraordinary specimen, we immediately realized its importance, not only as a new species, but also as possible evidence of the presence of ants in the Crato Formation," Lepeco notes.
Examining it with micro-computed tomography—a 3D imaging technique that uses X-rays to see inside an object—the team discovered that the ant was closely related to hell ants, which until now were only known from specimens preserved in Burmese amber, a type of amber found in Myanmar.
According to the authors, this discovery demonstrates that ants were widely distributed across the planet and must have repeatedly crossed Cretaceous landmasses. But what most astonished them were the specialized features of the hell ant.
Specialized traits"Although we expected to find traits typical of hell ants, we were surprised by the characteristics of their feeding apparatus," says Lepeco.
Unlike modern ants, which have laterally moving mandibles, this species had mandibles that ran parallel to the head and a facial projection anterior to the eyes, the study said.
"The discovery of such an anatomically specialized ant 113 million years ago challenges our assumptions about how quickly these insects developed complex adaptations. The intricate morphology suggests that even these early ants had already developed sophisticated predatory strategies significantly different from their modern counterparts ," the scientist adds.
The discovery of this new ant specimen raises broader questions about the evolutionary pressures that led to the hell ant's unique adaptations, the researchers say.
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