24-million-year-old fossil leaves found in Assam reveal ancient link to Western Ghats

Guwahati: Scientists have unearthed fossilised leaves in Makum Coalfield of Assam that date back approximately 24 million years.

The fossil leaves, studied by researchers from the Birbal Sahni Institute of Palaeosciences (BSIP) in Lucknow, bear a striking resemblance to modern plants of the Nothopegia genus—species that now exist only in the Western Ghats.

Published in the journal Review of Palaeobotany and Palynology, the study reveals that Northeast India once hosted a tropical climate ideal for such flora.

However, massive geological events such as the rise of the Himalayas triggered by tectonic plate movements—transformed the region’s environment drastically. These changes in temperature, rainfall, and wind patterns cooled the northeast, making it unsuitable for many tropical species like Nothopegia, which eventually disappeared from the region.

Today, Nothopegia survives in the ecologically stable Western Ghats, acting as a living relic of a bygone tropical era. Using advanced techniques like the CLAMP method, scientists confirmed that the late Oligocene climate in northeast India was warm and humid, resembling the current conditions in the Western Ghats.

“This fossil discovery is a window into the past that helps us understand the future,” said Dr. Harshita Bhatia, co-author of the study. She emphasized the urgent need to protect biodiversity hotspots like the Western Ghats, which serve as refuges for ancient lineages.

The findings underscore that extinction and species migration due to climate shifts have been ongoing processes for millions of years—trends that continue to impact global biodiversity.

Alarmingly, recent projections warn that over 60% of tropical endemic plant species could face extinction due to modern climate change, with the Western Ghats at risk of losing all its endemic species by 2050.