New Delhi: In a discovery that sheds fresh light on India’s ecological history, scientists have unearthed fossilized leaves in Assam’s Makum Coalfield that reveal a long-forgotten connection with the biodiversity of the Western Ghats. These leaves, dating back around 23–24 million years to the late Oligocene epoch, belong to the Nothopegia genus a group of tropical trees now found only in the lush rainforests of the Western Ghats.
The breakthrough study, led by researchers from the Birbal Sahni Institute of Palaeosciences (BSIP) in Lucknow, has been published in the Review of Palaeobotany and Palynology. It marks a major advance in understanding how India’s northeastern and southwestern ecological zones were once directly linked.
For decades, the Makum Coalfield has been known as a treasure trove of plant fossils. During their recent excavation, the research team discovered leaf impressions that bore a striking resemblance to modern-day Nothopegia species—trees currently thriving in the Western Ghats, a UNESCO World Heritage site and one of the planet’s richest biodiversity hotspots.
To verify the fossils’ identity, scientists employed a rigorous analysis involving morphological assessments, comparison with herbarium samples, and cluster analysis. The results confirmed that these ancient plants are indeed ancestors of the Nothopegia trees, which mysteriously vanished from Northeast India but managed to survive thousands of kilometers away in the Western Ghats.
To piece together how these tropical trees once flourished in Assam, the team turned to the Climate Leaf Analysis Multivariate Program (CLAMP), a method that reconstructs ancient climates using fossilized leaf characteristics. Their findings suggest that Assam’s climate in the late Oligocene was warm, humid, and tropical mirroring today’s conditions in the Western Ghats.
But this tropical paradise didn’t last. As the Himalayas rose dramatically millions of years ago, they disrupted weather patterns, cooled the region, and made it unsuitable for tropical flora like Nothopegia. The species, unable to survive in the changing northeast climate, retreated to the stable conditions of the Western Ghats where it endures to this day.
“This discovery is more than just a glimpse into ancient plant life,” said Dr. Harshita Bhatia, co-author of the study. “It offers a window into how life has historically adapted or failed to adapt to massive environmental changes. Understanding this could help guide conservation efforts in today’s rapidly changing climate.”
The study also highlights the critical importance of biodiversity refuges like the Western Ghats. These natural sanctuaries not only shelter rare species but also preserve evolutionary legacies that are millions of years old. As climate change accelerates in the modern era faster than ever in Earth’s history protecting such refuges could be key to ensuring species survival.
By combining fossil evidence with climate modeling, the research team has unveiled a forgotten chapter of India’s ecological past and underscored the fragile, enduring threads that connect distant regions. The story of Nothopegia stands as both a scientific milestone and a cautionary tale about the challenges of survival in a changing world.