GEOBOTANICAL ANALYSIS OF PLANT FOSSIL ASSEMBLAGES FROM THE UPPER PENNSYLVANIAN LIMNIC DEPOSITS OF THE NORTHERN CAUCASUS

Abstract

Analysis of plant fossil assemblages from the Upper Pennsylvanian deposits of the Northern Caucasus was carried out within the intervals, which are compared with the megafloral zones of the Stephanian of the Western European scale. The identification of the taxonomic composition and the interpretation of environments of the Late Pennsylvanian plant communities showed that the Northern Caucasus vegetation was represented by wetland and seasonally dry forests of river valleys. The wetland forests were composed of the calamitalean-fern and calamitalean-fern-pteridosperm communities of the shores of floodplain lakes and the lycopsid-calamitalean-fern-pteridosperm communities of floodplains. Throughout the Late Pennsylvanian (Stephanian and early Autunian), the most widespread taxa of wetland forests were lycophytes Subsigillaria brardii, calamitaleans with the stems of Calamites suckowii and the foliage of Annularia sphenophylloides, A. spinulosa, ferns Acitheca polymorpha, Cyathocarpus arboreus, C. cyatheus, ‘Pecopteris’ bredovii, Nemejcopteris feminaeformis, Diplazites unitus and pteridosperms Odontopteris brardii, Callipteridium gigas, C. pteridium, Pseudomariopteris cordato-ovata, Dicksonites sterzelii. The seasonally dry vegetation was widespread in the middle Stephanian (Stephanian B) and the late Stephanian–early Autunian (Stephanian C–early Autunian) and composed of the pteridosperm-conifer communities of river valley slopes. In the middle Stephanian, the drought-tolerant plants were represented by pteridosperms Odontopteris subcrenulata, Sphenopteridium cf. germanicum, Taeniopteris jejunata, cordaitaleans Cordaites sp. and conifers Walchia piniformis, Culmitzschia frondosa. In the late Stephanian–early Autunian, the seasonally dry vegetation of the river valley slopes included pteridosperms Autunia conferta, Dichophyllum flabelliferum, Sphenopteridium germanicum, Taeniopteris jejunata, conifers Walchia piniformis, Otovicia hypnoides and cordaitaleans Cordaites sp.