FOSSILS ET AL.
The Oldest Ant Ever Found Was a Cretaceous Predator with Scythe-Like Jaws
A newly discovered 113-million-year-old fossil of a Brazilian ‘hell ant’ from the Lower Cretaceous rewrites the evolutionary history of ants
I have had a long-standing interest in entomology, and this week I learned about a recent with surprising findings about the evolution of ants, namely members of the extinct Haidomyrmecinae subfamily.
Ants have persisted for over 100 million years, enduring multiple mass extinction events, and are still one of the biggest insect families. We already knew they were abundant in the last stages of the Cretaceous, as the proportion of ants preserved as fossils increases toward the end of the period.
Since then, ants have populated the world and can be found in the most diverse ecosystems. “Modern ants are among the most ecologically dominant animal groups on Earth, with their diversity shaped by global events occurring since their origin in the late Mesozoic.” ( et al., 2025)
A prehistoric hell ant that lived with dinosaurs
The novel research published in describes how a recently discovered ant species advances by more than 13 million years the previous oldest fossil record of the Formicidae family, which until then had been restricted to specimens preserved in amber from France and Myanmar.
The new species of hell ant represents the oldest undisputed geological record of ants. The research significantly extends the timeline of ant evolution and suggests that they were already widely distributed during the Lower Cretaceous.
Thanks to the expert eye of Anderson Lepeco, a researcher at the Zoology Museum of the University of São Paulo (USP), an almost-forgotten ant fossil discovered in a museum collection in Brazil in September 2024 has now been identified as the oldest known ant specimen.
The fortunate discovery occurred while Lepeco was examining a collection of fossils housed at the museum, originally excavated from the Crato Formation, a geological deposit in the Araripe Basin of Ceará, Brazil.
“The origin of ants likely occurred between the Late Jurassic and the Early Cretaceous and Haidomyrecinae have been suggested as the earliest-diverging ant lineage. Given the available fossil data, hell ants seem to represent the oldest known major group of ants to diversify and spread across the globe.” ( et al., 2025)
The specimen has been classified as a member of the extinct subfamily Haidomyrmecinae,¹ known as the “hell ant”, which lived during the Cretaceous period.
Entomologists named it Vulcanidris cratensis, a reference to the region where it was first found in Northwestern Brazil. It also “honors the family Vulcano, including Maria Aparecida Vulcano, who has assembled a very important Crato collection bearing her name, recently donated to MZSP. The genus name has the Greek word ‘idris’ as a suffix, meaning “the provident one” (i.e., an ant), which has often been used for naming ant genera.” ( et al., 2025).
Morphology and specialized predatory features
The team of Brazilian entomologists used computerized tomography, allowing a detailed description of the insect’s morphology and confirming that it is the oldest representative of the extinct subfamily Haidomyrmecinae.
What experts find most interesting about this species is the insect morphology when compared to modern ants. The latter have jaws that close laterally from side to side. However, the Vulcanidris cratensis had scythe-shaped mandibles that protruded forward, parallel to the head and close to the eyes.
Prehistoric hell ants are “readily recognized by their bizarre scythe-like mandibles, often pointed upward and coupled with facial projections, representing unparalleled morphologies in the context of modern ants” ( et al., 2025).
The newly identified species also had some characteristics similar to those of wasps, which indicates common ancestry between the two groups. For instance, the ant’s wings had many more veins than those of modern ants.
Hell ants were extraordinary insects with highly specialized traits. They are usually portrayed as predatory, even if recent findings have presented alternative theories.³
Lepeteco’s research shows how prehistoric hell ants had large jaws. Were they used for impaling or for crushing their prey?
The precise function of their jaws remains uncertain, but Vulcanidris cratensis may have employed an unusual method of capturing prey. Lepeco proposed that its jaws functioned like a kind of forklift, lifting prey upward.
“The mandibular foramina are close to each other, receiving the proximally constricted mandibles, even resembling antennal sockets. This conformation suggests a higher capacity of mandible motion, a trait evolved by ants through different mechanisms” ( et al., 2025).
These are extraordinary predatory adaptations, I find this interesting if we think about their ancient lineage, meaning “this species already had highly specialized anatomical features, suggesting unique hunting behaviors.” ( et al., 2025)⁴
The new genus can be confidently placed in Formicoidea for its prognathous head.
“I was shocked to see that strange projection on the front of this insect’s head,” said Lepeco. “Other hell ants had already been described with unusual mandibles, but always as specimens preserved in amber.” It’s rare to find insects preserved in rock. ( et al., 2025)
Although hell ants have been described in amber before, this was the first time we were able to visualize them in a rock fossil, as highlighted by the lead researcher.
Images taken with micro-computed tomography (a 3D imaging technique that uses X-rays to visualize the inside of the ant), helped the authors place the new species among the Haidomyrmecinae “based on the presence of a facial projection coupled with mandibles that articulate ventrally on the head.” ( et al., 2025).
This advanced imaging technique also revealed the Vulcanidris cratensis was closely related to other hell ants known only from Burmese amber fossils.
A new insight into the early diversification of ants
The newly reported species represents the oldest definitive ant known to science and also the most complete evidence for the early evolution of ants in the fossil record.⁵
Computed tomography allowed the team to identify and confirm a close relationship between the novel Vulcanidris genus and the Burmese amber fossil genus Aquilomyrmex.
The research also reveals how hell ants achieved a wide geographical distribution during the Cretaceous, spreading through Laurasia (i.e., Canada and France) and South America.
According to the authors the discovery of Vulcanidris cratensis “allows us to bridge the gap between ants and their wasp ancestors, pushing the earliest direct evidence of ants on Earth back to 113 mya, predating the fossil Formicidae from deposits in France and Myanmar by over 13 million years and aiding in calibrating the ant tree of life.” ( et al., 2025)
It also confirms hell ants exhibited a wide ecological range, occurring in remarkably different environments throughout the globe, and how they exhibited specialized predatory morphologies; their food resources were present in regions with very different ecological settings.
I find this study highly relevant as it reveals a wider and more diverse ancient world for ants while amplifying our knowledge about their evolution and historical distribution. This Brazilian ant fossil reveals that the species had already spread to previously unknown regions.⁶
“It is not the strongest of the species that survives, not the most intelligent that survives. It is the one that is the most adaptable to change.”―
References:
- Anderson Lapeco et al. (2025). A hell ant from the Lower Cretaceous of Brazil. Curr Biol., 35(9):2146–2153.e2. DOI:
Notes:
- “The so-called hell ants of the subfamily Haidomyrmecinae comprise a group of morphologically unique ants exclusive to the Cretaceous. They represent some of the earliest known ants in the fossil record, preserved as amber inclusions in deposits in France, Myanmar, and Canada.” ( et al., 2025) Hell ants are extinct and not to be confounded with South American army ants (Eciton), portrayed in movies like (1957) and (1998).
- “The Crato Formation, part of the Santana Group in the Araripe Basin, is generally regarded as dating to the late Aptian stage of the Lower Cretaceous.” ( et al., 2025)
- “In contrast, there is no evidence that ants were dominant predators in the Crato paleoenvironment, given their rarity. Other groups, such as staphylinids, apoid wasps, and blattulid cockroaches, are more commonly recorded, also indicating that the region sustained a relatively diverse assemblage of predatory insects.” ( et al., 2025)
- “From this viewpoint, we can infer that their presumed specific predatory behaviors were already established by the Lower Cretaceous.” ( et al., 2025)
- The research led by Anderson Lepeco was the first to document a hell ant recorded as a rock fossil, providing a unique opportunity to study the preservation of their unusual morphology in this medium.
- “It has been suggested that the spread of flowering plant lineages through global ecosystems has buffered ant lineages against extinction, providing new niches in which they could adapt and diversify.” ( et al., 2025)
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