Study of fossil wood from the upper Tertiary sediments (Siwalik) of Arunachal Pradesh, India and its implication in palaeoecological and phytogeographical interpretations

Ten species of fossil dicotyledonous woods are described from the upper Ter tiary sediments (Siwalik Group) of the northeast Himalayan foot hills (Arun achal Pradesh State), India. They show close similarity with wood of extant Shorea (Dipterocarpaceae), Eurphoria (Sapindaceae), Gluta (Anacardiaceae), Cassia, Cynometra, Afzelia-lntsia, Sindora and Albizia (Fabaceae) and Term inalia (Combretaceae). This small floral assemblage is in its composition v ery similar to that of the Brahmaputra Valley of Assam but differs slightly from the Siwalik flora of the northwestern Himalayas. Comparison with mode m plants indicates that the assemblage was dominated by tropical evergreen forest trees along with some littoral and swampy elements. The occurrence o f Sindora, a typical Malaysian element, along with some other taxa suggests that an exchange of floral elements took place between India and Southeast Asia during the late Tertiary. (C) 1999 Elsevier Science B.V. All rights r eserved.