Article: Tertiary Homoptera of Stavropol and a method of reconstruction of continental palaeobiocoenoses
The fossil remains of insects from Vishnevaya Balka are the principal basis for studies of the entomofauna of the Caucasus in the Miocene period. The representatives of the Homoptera (monophagous and oligophagous) which are closely associated with certain genera and species of plants, have been carefully studied. The wealth of species of Psyllidea (mainly monophagous) allows us on the basis of biocoenotic relationships to enlarge the list of plants existing in the Stavropol region in Karagan times.The geological section of Vishnevaya Balka comprises a considerable portion of the Karagan horizon from above the Chockrack boundary. It shows some regularity in the burials of the representatives of different orders of insects by layers. Diptera recorded in the lower layers as only 17%, rise to 48% in the upper layers. Homoptera dominate in the lower layers, with 35%. The beetles and Hymenoptera make up no more than 3-10%; Trichoptera 15-24%, falling in the upper layer I to 7-8%. The biocoenotic relationships of Homoptera and Diptera enable us to estimate the changes of biocoenoses in time. During the deposition of the lower layers a woody vegetation (trees and shrubs) prevailed while herbaceous vegetation was characteristic of the upper layers, pointing to the gradual steppization of the area.