Discuss how fossil botanical evidence from northeast India helps reconstruct the climatic and ecological impact of the Himalayan orogeny.

Q. Discuss how fossil botanical evidence from northeast India helps reconstruct the climatic and ecological impact of the Himalayan orogeny. (15 marks, 250-350 words)

Plant fossils act as natural climate archives, since leaf form responds directly to temperature and rainfall. The Oligocene–Miocene coal-bearing sediments of northeast India, notably Assam's Makum Coalfield (Tikak Parbat Formation), preserve such a record from before the Himalaya attained its present height, allowing scientists to reconstruct how mountain-building reshaped the region's climate and its living world.

Reconstructing the climatic impact

• Leaf-based climate reconstruction from Makum fossils shows northeast India was warm and humid in the late Oligocene, resembling today's tropical wet forests [2].
• The tectonic rise of the Himalaya subsequently altered temperature, rainfall and wind regimes, making the region inhospitable to several tropical lineages [2].
• Fossil leaves from Nagaland and Kashmir extend this method — linking Indian monsoon behaviour to distant climate drivers, and dating Himalaya-driven change in Kashmir's weather to roughly four million years ago [2].

Reconstructing the ecological impact

• Migration: Nothopegia leaves dated ~24–23 million years — the genus's oldest known fossil record — prove it once grew in Assam, though it survives today only in the climatically stable Western Ghats [2].
• Survival in situ: four fossil leaves of the Pandanaceae (screw-pine, source of fragrant kewra) show this lineage has persisted in the subcontinent for about 24 million years, outlasting the orogeny itself [1].
• Together these establish India as a refugium for ancient plant lineages, and demonstrate that climate-driven extinction and range shifts are deep-time processes, not modern novelties [2].

Contemporary relevance

• Past biotic responses offer analogues for predicting how present-day forests may respond to rapid warming [2].
• Such work, led by the Birbal Sahni Institute of Palaeosciences under the Department of Science & Technology, strengthens indigenous palaeoscience capacity [1][2].

Fossil botany thus converts northeast India's coalfields into a chronicle of the Himalaya's climatic legacy. Sustained investment in palaeoclimate research, integrated with biodiversity-hotspot conservation, would let this deep-time evidence directly inform India's climate-adaptation and species-protection strategies.

(~325 words)

Sources: 1. Plant yielding the fragrant kewra is older than human civilization & predates Himalaya formation — PIB, Ministry of Science & Technology (15 July 2026) — kewra/Pandanaceae fossil leaves, ~24 million years, Makum Coalfield; BSIP/DST authorship 2. A 24-million-year-old secret unearthed by the discovery of fossil leaves in the Makum Coalfield of Assam — Department of Science & Technology — late Oligocene warm-humid climate, Himalayan uplift-driven climate change, Nothopegia migration to the Western Ghats, present-day climate relevance