Ants are arguably the greatest success
story in the history of terrestrial metazoa.
On average, ants monopolize 15–20%
of the terrestrial animal biomass, and in
tropical regions where ants are especially
abundant, they monopolize 25% or more.
But ants did not always run the world. They
do not appear in the fossil record until the
mid-Cretaceous, and for more than the first
half of their history—a period spanning 60
to 80 million years—ants occupied a relatively
modest position in the terrestrial biosphere.
To understand the factors, both
ecological and historical, that contributed to
the rise of the ants, we require a clearer
picture of the stepwise evolution of the
major ant lineages. Now, Grimaldi and Agosti
(1) report in a recent issue of PNAS the
remarkable discovery of a worker ant, preserved
in amber for over 90 million years,
that is clearly assignable to a modern ant
subfamily that contains many familiar extant
species, including carpenter ants. Combined
with other paleontological and phylogenetic
information, this unexpected fossil strongly
indicates that the diversification of many ant
subfamilies occurred earlier and more rapidly
than previously suspected.