Аннотация:We consider morphological diversity of ants from mid-Cretaceous Burmese amber. An eco-ethological hypothesis concerning its origin and features of Mesozoic and Cenozoic ant communities is proposed. It appears that some morphological features of representatives of the stem taxa allow us to speak about the absence of effective communication and, subsequently, group foraging in these ants. Therefore, the diversity of primitive Cretaceous ants, as predators, reflects their food specialization according to types of prey, on condition of their social lifestyle, that results in division of the ecological space among ant species into ecological niches. The occurrence of both effective communication and group foraging (mobilization) in the crown ant taxa, as crucial adaptation, has permitted them to exceed the bounds of niches of specialized predators, since type and size of prey are not strictly correlated to size of an ant and its mandibles; it also has given a chance to maintain large colonies. Due to this, myrmecocomplexes of modern ants are arranged on the principle of colonies dominance rather than the principle of division of ecological niches, like Mesozoic.