New Jersey Institute of Technology Jersey City, New Jersey
Even as extant lineages represent an expansive morphological assemblage spanning over 13,000 species, the fossil record reveals that some extinct phenotypes lay outside of the boundaries of modern ant diversity. There are over 750 described fossil ant species from 70 deposits worldwide. Most fossil species – particularly those from the Cenozoic (66 million years ago to the present) – can be attributed to modern taxa, however some fossils belong to lineages that diverged from exant ants prior to the most common ancestor of all living species. These extinct stem-ants include examples of dramatically aberrant morphology such as haidomyrmecine hell ants with scythe-like mandibles and cranial horns as well as generalized phenotypes that are presumed to be plesiomorphic. What might explain the distinct morphology found in the earliest known ants? Here, new fossil evidence and phylogenetic comparative methods shed light on the evolutionary pathways that shaped extinct diversity.
