A 16-million-year-old ant, trapped in Dominican amber, sheds light on the evolution of an inconspicuous species.
This unprecedented discovery, published in
Proceedings of the Royal Society B, overturns knowledge about ants of the
Basiceros genus. Known for their ability to blend into the ground, these insects were previously thought to be confined to the tropical forests of South America. The fossil proves they also inhabited the Caribbean millions of years ago.
Illustration of the volumetric rendering and measurement process performed using volumetric renders of Basiceros enana.
Image credit: Fiorentino et al., doi: 10.1098/rspb.2024.2171. An extinct species with surprising adaptations
Named
Basiceros enana, this fossil ant measures 5.13 mm (0.2 inches), nearly half the size of its modern descendants. Microtomographic analyses reveal specialized hairs identical to those of modern species, used to stick soil particles and camouflage themselves.
This similarity suggests that the camouflage strategy of
Basiceros was already optimized 16 million years ago. Researchers also highlight the presence of serrated mandibles, typical of predators, and a distinctive cranial morphology.
The extinction of this species in the Caribbean raises questions. Ecological changes during the Miocene, such as niche alterations or interspecies competition, could explain its local disappearance.
An evolutionary history to rewrite
The presence of
Basiceros enana in Dominican amber indicates a past geographical distribution far wider than previously estimated. Scientists suggest ancient land bridges connecting the continent to the islands, facilitating the dispersal of these ants.
The study combines 3D imaging and molecular dating to trace their evolution. Contrary to earlier hypotheses,
Basiceros ants may have rapidly increased in size, growing from 5 to 9 mm (0.2 to 0.35 inches) over 20 million years.
This work underscores the importance of fossils for understanding past biodiversity. Nearly 40% of Caribbean ant genera have disappeared since the Miocene, a decline that sheds light on current conservation challenges.
Article author: Cédric DEPOND