Fossil Record

Auchenorrhyncha arose in the Paleozoic, first appearing in the fossil record in the Lower Permian (280 mya) and, judging from the abundance of forms described from Permian strata, they diversified explosively. These early auchenorrhynchans had adults with well-developed jumping abilities and somewhat resembled modern leafhoppers and spittlebugs, but nymphs (juveniles) associated with these insects were bizarrely flattened or biscuitlike, with short legs, foliaceous lobes on the head, thorax, and abdomen (similar to those of some modern Psyllidae) and elongate mouthparts, suggesting a sessile, cryptic lifestyle. The fulgoromorphan and cicadomorphan lineages (Table I) apparently diverged by the middle Permian. By the late Permian, Fulgoroidea appeared and Cicadomorpha (sensu lato) had diverged into the Pereboreoidea, comprising three extinct families of large cicada-like insects, and the smaller Prosboloidea, from which the three modern cicadomorphan superfamilies apparently arose. Cicadomor-phans with a greatly inflated frontoclypeus (Clypeata in the paleontological literature = Clypeorrhyncha) did not appear until the Mesozoic. Prior to that, the head of Cicadomorpha resembled that of modern Psyllidae in having the frontovertex extended ventrad on the face to the antennal ledges and the lateral ocelli situated close to the eyes. This change in head structure is thought to have been associated with a shift from phloem to xylem feeding. Xylem feeding was apparently the predominant feeding strategy of the group throughout the Mesozoic, but in the late Cretaceous or early Tertiary the major lineages of phloem-feeding leafhoppers and treehoppers, which predominate in the recent fauna, arose. In these insects, the frontoclypeus became more flattened, probably because of the reduction in size of the cibarial dilator muscles. This was presumably in response to a shift from feeding on xylem, which is under negative pressure, to phloem, which is under positive pressure. Cicadoidea and Cercopoidea first appeared in the Triassic, and Membracoidea in the Jurassic. With the exception of Tettigarctidae, which arose in the late Triassic and is now confined to Australia, extant families of these groups do not appear in the fossil record until the Cretaceous or early Tertiary. Most Auchenorrhyncha from Baltic and Dominican amber of the Tertiary age are virtually indistinguishable from modern forms.

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