A badass piece of amber that has preserved the battle between an ant and a nymph for 99 million years shows how one ancient ant species used its impressive headgear to hunt. Published in the journal Current Biology, the discovery gives a detailed picture of the scythe-like mandibles and horn appendage that gave this ant its bitchin’ nickname, “hell ant”.
The newly identified and predatory arthropod species, more officially known as Ceratomyrmex ellenbergeri, was alive during the Cretaceous period. The species was identified from the amber specimen, which was recovered in Myanmar, but hell ants as an arthropod group were first unearthed around 100 years ago.
This fossil is of particular interest as capturing behaviors suspended in animation for millions of years is not a common occurrence, but in this instance, the hell ant can clearly be seen clutching its final victim, an unsuspecting, now-extinct relative of the cockroach known as Caputoraptor elegans.
"Fossilized behavior is exceedingly rare, predation especially so,” said Phillip Barden, assistant professor at the New Jersey Institute of Technology's Department of Biological Sciences and lead author of the study, in a statement. “As paleontologists, we speculate about the function of ancient adaptations using available evidence, but to see an extinct predator caught in the act of capturing its prey is invaluable. This fossilized predation confirms our hypothesis for how hell ant mouthparts worked... The only way for prey to be captured in such an arrangement is for the ant mouthparts to move up and downward in a direction unlike that of all living ants and nearly all insects."
Since their discovery hell ants have puzzled entomologists as their mouthparts are very distinct from ants still strutting the globe today. The rare fossil demonstrates how the hell ant's chosen feeding style could explain why its mouthparts move differently to extant ants whose mouthparts grasp by moving together laterally.
Mandible and horn morphology among the hell ants gets pretty weird, too. To date, 16 species have been identified, and while some are comparatively unarmed, others such as Linguamyrmex vladi, or "Vlad the Impaler" (discovered by Barden and colleagues in 2017) was thought to have used a metal-reinforced horn as a spear, impaling their prey and consuming their body contents. Grim.
"Integration is a powerful shaping force in evolutionary biology ... when anatomical parts function together for the first time, this opens up new evolutionary trajectories as the two features evolve in concert," explained Barden. "The consequences of this innovation in mouthpart movement with the hell ants are remarkable. While no modern ants have horns of any kind, some species of hell ant possess horns coated with serrated teeth, and others like Vlad are suspected to have reinforced its horn with metal to prevent its own bite from impaling itself."
2020 might have been an absolute shocker of a year, but we do enjoy some perks over the Cretaceous...