study of three species of lobifolia rotundifolia, ptilophyllum vasekgahense and nilssonia herriesi from plant macrofossils of late liassic-early dogger (toarcin-bajocian) deposits in eshkevarat-e-olia region, central alborz, north of iran

study of plant macrofossils of jurassic sediments of shemshak group in eshkevarat-e-olia areas led to identification of two species consisting lobifolia rotundifolia from ferns group (division pteridophyta & filicales order) and ptilophyllum vasekgahense from gymnospermae group (division cycadophyta & order bennettitales) that had been reported from rhaetian (late triassic) and dogger (middle jurassic) and in this investigation, they are reported from late liassic (toarcian) for the first time. also the species of nilssonia herriesi from cycadophyta division and order cycadales are reported for the first time from alborz structural – facies region. base on stratigraphical distribution of accompanied macrofossils species such as klukia exilis, klukia westii, coniopteris hymenophylloides, todites williamsoni, cladophlebis aktashensis, pseudoctenis herriesi, nilssonia macrophylla, nilssonia tenuinervis, ptilophyllum cutchense, ptilophyllum sahnii, ptilophyllum sakrigaliensis and elitides thomasi, the age of the shemshak formatio in the eshkevarat-e-olia is assigned to be toarcian - bajocian (late liassic–early dogger).