Fossil flora from the Himalayan foot-hills of Darjeeling District, West Bengal and its palaeoecological and phytogeographical significance

Abstract

An assemblage of plant megafossils comprising leaf-impressions, fruits and culm-impression recovered from the Lower-Middle Siwalik sediments near Oodlabari, Darjeeling District, West Bengal (India) has been described. It consists of 32 species of dicots and one species of monocots (Bamboo) belonging to 32 genera of 22 families. Out of them 11 genera viz., Mitrephora, Casearia, Alsodeia, Pterospermum, Grewia, Nothopagia, Combretum, Vernonia, Alstonia, Callicarpa and Macaranga are new to the Siwalik flora. An analysis of the floral assemblage with respect to the distribution pattern of modern equivalent taxa reveals the presence of three types of elements, viz., (i) evergreen (60.61%). (ii) evergreen to deciduous (18.18%) and (iii) moist-deciduous (21.21%), which indicate the prevalence of warm and humid climate in the region during the deposition of Siwalik sediments. It is also interesting to mention that the assemblage is dominated by 19 Indo-Malayan elements revealing a fair exchange of floral elements between the two subcontinents during Miocene.