Plant megafossils from the Siwalik sediments of Koilabas, central Himalaya, Nepal and their impact on palaeoenvironment

Abstract

A systematic study on plant megafossils comprising mainly leaf-impessions from the Himalayan foot-hills near Koilabas, Nepal has been carried out. The comparative study of plant fossils with the extant taxa reveals the occurrence of 26 new species belonging to 14 dicotyledonous families. The floral assemblage suggests that tropical evergreen to moist deciduous vegetation flourished around Koilabas area during the Siwalik time. The habit and habitat of the comparable extant taxa indicate a warm humid climate all along the foot-hills during the Mio-Pliocene. The presence of a sizeable number of Indo-Malayan taxa in the present assemblage shows fair exchange of floral elements between two subcontinents and further extension towards Nepal territory. The significance of physiognomic characters of the leaf-impressions in relation to environment has also been discussed.