Evidence of the Oldest Extant Vascular Plant (horsetails) from the Indian Cenozoic

(Equisetaceae) has long been a focus of attention for botanists and palaeontologists because, given its extensive and well-documented fossil record, it is considered the oldest extant vascular plant and a key element in understanding vascular plant evolution. However, to date, no authentic fossil evidence of has been found from the Indian Cenozoic. Here, we describe a new fossil species namely, sp. nov., recovered from the middle Siwalik (Late Miocene) sediments of Himachal Pradesh, western Himalaya. We identified fossil specimens based on morphological and epidermal characters. In addition, X-Ray diffraction (XRD) analysis was used to determine the mineral composition of compressed stems of . The close affinity of our recovered Siwalik fossils to is supported by the presence of both macromorphological and epidermal characters. Because generally grows in wet conditions around water reservoirs, our findings indicate that the fossil locality was humid and surrounded by swamp and lowland regions during deposition. Ample fossil evidence indicates that this sphenopsid once existed in the western Himalaya during the Siwalik period. However, at present is confined to a particular area of our fossil locality, probably a consequence of severe environmental changes coupled with competition from opportunistic angiosperms. Our discovery of fossils in appreciable numbers from the Siwalik sediments of the Himachal Himalayas is unique and constitutes the first reliable recognition of from the Indian Cenozoic.