The Aphidoidea contains most of the extant families and species of aphids. Two additional extant families of aphids, the Phylloxeridae and Adelgidae, can be found in the supefamily Phylloxeroidea. Although the fossil evidence suggests that the Aphidoidea diversified concomitant with the first angiosperms in the lower Cretaceous (approx. 140 MY), it is likely that the family is much older. For example, three groups, the Prociphilini (Pemphigidae), Mindarus (Mindaridae) and Neophyllis (Drepanosiphidae), have what are probably ancient ties to conifers. Therefore 140 MY should be considered a minimum estimate of the age of the superfamily with something over 200 MY a serious possibility. Most aphid families went extinct at the Cretaceous-Teriary (K/T) boundary along with the dinosuars and the majority of extant taxa can be found in the family Aphididae, which underwent a striking radiation in the Miocene (approx. 5-26 MY). There are excellent discussions of aphid fossils and the geological record in Heie (1987, 1994a).