The rise of the ants revealed in amber

International audienceAnts are a conspicuous element of modern terrestrial ecosystems, are distributedvirtually worldwide, and have an expansive range of behaviors and interactionswith other organisms. The vast majority of over 13,000 extant species belongs inthe "big four" subfamilies Dolichoderinae, Formicinae, Myrmicinae, and Ponerinae.However, despite the presence of ants on Earth for over 100 million years, theirrise to dominance has been relatively slow, and they appear to have been onlymoderately abundant and diverse for about the first half of their history. This is welldocumented in the fossil record and a focus is made here on fossils entombedin amber, as they harbor the finest preservation and offer a tantalizing glimpse ofant diversity at various points in the past. Ants never surpass 1.5% of the totalinsects in Cretaceous amber deposits, where they mostly comprise stem-groupants that did not survive beyond the Cretaceous-Cenozoic boundary. In EarlyEocene amber, prevalence increases up to 10%, and all identifiable ants areassignable to crown lineages. Also, dominance of the "big four" subfamilies isalready largely consistent into the Eocene, during which a burst of diversificationevidently occurred. In Miocene amber, ant prevalencereaches 25-36% and allspecimens are assignable to extant genera. A temporal midpoint in the history ofants is thus reached in the Early Eocene, - 50 million years ago, with a distinctshift observed in their abundance and diversity. Finally, all modern lineages hadappeared by the middle Miocene, -15 Ma, and major changes since then mostlycomprise their geographical diversification