An early ant evolution based on fossils?

A new article by Perrichot V., S. Lacau, D. Néraudeau and A. Nel on an eventual hypothesis of an earlier evolution of ants than what was proposed earlier.
The article is untitled: Fossil evidence for the early ant evolution and is published in Naturwissenschaften 95:85-90
Link to the article:
http://www.springerlink.com/content/dgqj3574h1j54663/fulltext.pdf

Here is the abstract:

Ants are one of the most studied insects in the world; and the literature devoted to their origin and evolution, systematics, ecology, or interactions with plants, fungi and other organisms is prolific. However, no consensus yet exists on the age estimate of the first Formicidae or on the origin of their eusociality. We review the fossil and biogeographical record of all known Cretaceous ants. We discuss the possible origin of the Formicidae with emphasis on the most primitive subfamily Sphecomyrminae according to its distribution and the Early Cretaceous palaeogeography. And we review the evidence of true castes and eusociality of the early ants regarding their morphological features and their manner of preservation in amber. The mid-Cretaceous amber forest from south-western France where some of the oldest known ants lived, corresponded to a moist tropical forest close to the shore with a dominance of gymnosperm trees but where angiosperms (flowering plants) were already diversified. This palaeoenvironmental reconstruction supports an initial radiation of ants in forest ground litter coincident with the rise of angiosperms, as recently proposed as an ecological.