Abstract
Fossil leaf material of Polenta (Bertinoro, Forlì-Cesena Province) originally described by P. Principi (1922; 1926) were studied morphologically to assess the taxonomic composition of the plant assemblage and carry out a vegetation analysis.
The flora includes 48 vascular plant taxa with 5 conifers and 38 angiosperms. Several fossil species well known in the late Miocene of Italy, France and Greece were detected.
The most frequent being conifers of Taxodium dubium, Sequoia abietina, Glyptostrobus europeus, Pinus spp. and representatives of the Lauraceae (Daphnogene polymorpha, Laurophyllum sp.), Platanaceae (Platanus leucophylla), Fagaceae (Fagus gussonii, Quercus pseudocastanea, Q. kubinyii, Q. drymeja, Q. roburoides, Trigonobalanopsis rhamnoides), Magnoliaceae (Magnolia liblarensis, Sassafras ferretianum), Juglandaceae ("Juglans" acuminata, Pterocarya paradisiaca), Salicaceae (Populus populina, P. balsamoides, Salix sp.), Ulmaceae (Zelkova zelkovifolia), Sapindaceae (Acer integrilobum, A. tricuspidatum), Leguminosae and Monocotyledonae. Unique occurrences represented by few or one samples are Ginkgo adiantoides, Ilex geissertii, Tilia mastajana and flower remains described as Anthites malvaeformis.
The general palaeovegetation structure of the Polenta plant assemblage corresponds to the vegetation transect of the Evaporitic Messinian with swamp, riparian vegetation, and zonal "subtropical humid forest". The results of IPR vegetation analysis for the zonal upland vegetation indicate a transitional (ecotone) vegetation type between "Broad-leaved Deciduous Forest" and "Mixed Mesophytic Forest".
The Polenta plant assemblage shows a higher frequency of the broad-leaved deciduous elements than those of evergreen and sclerophyllous that is contradict to other close located Messinian plant assemblage of Monte Tondo and Tossignano (Vena del Gesso, Romagna Apennines, Northern Italy).