New Jersey Institute of Technology researchers uncover evidence of 16-million-year-old ant from the Caribbean.
Basiceros dirt ants, known for their remarkable ability to blend seamlessly into their surroundings, have long fascinated biologists. These unique ants, native to Neotropical regions, are distinguished by their larger size compared to other ants with similar camouflage abilities. They use specialized hairs on their bodies to trap dirt and leaf particles, effectively hiding from predators and prey alike.
Now, a groundbreaking discovery by a team of researchers at the New Jersey Institute of Technology (NJIT) has shed new light on the evolutionary history of these stealthy insects. The team has uncovered the first-ever fossil of the Basiceros genus — ‘Basiceros enana sp. nov.’ — preserved in 16-million-year-old Dominican amber.
This fossil provides the first concrete evidence that the dirt ants once inhabited the Caribbean millions of years ago, thereby expanding our understanding of their geographic range and evolutionary history.
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The newly discovered fossil represents a much smaller species than its modern-day relatives. ‘Basiceros enana’, measuring just 5.13 millimeters, is the smallest known member of the Basiceros lineage.
In contrast, modern dirt ants can grow up to 9 millimeters in length. Despite this size difference, the fossil reveals that the ancient ant already possessed many of the same cryptic features that enable today’s dirt ants to remain virtually invisible in their environment.
Scientists believe that the existence of these camouflage traits dates back at least 16 million years, indicating a long history of survival through stealth. The study suggests that Basiceros ants have undergone rapid body size expansion throughout their evolution, doubling in size over the past 20 million years.
“We’re seeing an amazing glimpse into the past,” said lead researcher Dr. Fiorentino. “This fossil shows that not only did these ants live in the Caribbean millions of years ago, but they were already equipped with the specialized adaptations that help them remain nearly invisible — a strategy that still serves them well today.”
Basiceros ants are best known for their “crypsis” — their ability to remain undetected by blending in with the leaf litter and soil. The fossil reveals that ‘Basiceros enana’ possessed two layers of specialized hairs on its body: longer, erect “brush hairs” and shorter “holding hairs.” These hairs bind dirt and leaf litter particles to the ant’s body, making it difficult to spot in the ground.
While these adaptations are critical for survival today, they were already present in this ancient species. The discovery raises questions about how these cryptic features evolved and how the ants’ ability to camouflage helped them thrive in their environment.
“What this shows is that playing dead and hiding pays off,” said Fiorentino. “Uncovering a unique fossil like this helps us understand how long organisms may have been employing this strategy, though the presence of these characteristics does not necessarily guarantee they behaved in the same way.”
In addition to their cryptic features, the fossil reveals that ‘Basiceros enana’ shared other distinct morphological characteristics with modern dirt ants, including an upturned propodeal spine, a trapezoid-shaped head, and powerful mandibles with 12 triangular teeth used for hunting.
Despite their remarkable adaptations, ‘Basiceros enana’ ultimately vanished from the Caribbean around 5.3 million years ago during the Miocene epoch, likely due to significant ecological changes in the region.
The study highlights how environmental shifts during this period led to the extinction of these cryptic ants from the Caribbean. However, their descendants continue to thrive today in Neotropical rainforests from Costa Rica to Brazil.
“This discovery adds an important chapter to our understanding of how ants have evolved and adapted to their environments,” said Fiorentino. “It also raises new questions about how these ants reached their current habitats and how they might have dispersed across different regions over time.”
The team used cutting-edge imaging technology, including micro-CT scanning, to examine the fossil in intricate detail. This advanced technique allowed researchers to visualize features that were otherwise impossible to detect, providing invaluable insights into the life of this ancient species.
As scientists continue to study the fossil, they hope to gain a deeper understanding of the evolutionary history of Basiceros ants and other cryptic species. The discovery of ‘Basiceros enana’ represents a significant step forward in the study of ant evolution, serving as a reminder of how nature’s most elusive creatures have been refining their survival strategies for millions of years.
With contributions from the New Jersey Institute of Technology and ongoing research, we may gain even more insight into the hidden lives of these stealthy ants and their ancient ancestors.
Journal Reference:
- Gianpiero Fiorentino, Rodolfo Probst, Adrian Richter, Evan P. Economo and Phillip Barden. A fossil-informed pattern of body size increase and local extinction in Basiceros dirt ants (Hymenoptera: Formicidae). Proceedings of the Royal Society B. DOI: 10.1098/rspb.2024.2171
Source: Tech Explorist