Palaeontologists find 4.5-million-year-old rare gourami fish fossil in Dehradun’s Shivalik range

Palaeontologists at the Wadia Institute of Himalayan Geology have made an enormous breakthrough, revolutionising what we know about India's geological past. They have discovered some of the oldest known aquatic fossils in the world (indicating the existence of ancient perennial water bodies), dating back 4.5 million years and found in the Shivaliks' foothills (near Mohand, along the Saharanpur-Dehradun border). This discovery is particularly significant, as for thousands of years, the Shivalik Hills were only known for containing terrestrial animal fossils. The researchers identified their specimens - fossilized fish ear stones (otoliths) from freshwater species, including a very rare freshwater fish called the gourami. This discovery allows us to learn much more about the Pliocene period (5 million to 2 million years ago), providing the first evidence of ‘statically stable’ freshwater body environments in northern India, which supported an aquatic food chain of complex organisms and were surrounded by dense/much more than normal vegetation. These findings challenge previous assumptions, painting a vivid picture of a prehistoric landscape defined by lush, thriving permanent waterways. These paleo-environmental insights reconstruct a lost aquatic corridor, revealing a vibrant prehistoric ecosystem that fundamentally reshapes our understanding of the Shivaliks. This evidence confirms that northern India once served as a critical refugium for diverse aquatic life during a shifting climate and this discovery essentially redefines the Shivalik range as a cradle for Pliocene biodiversity. This groundbreaking evidence redefines the Shivalik range as a pivotal sanctuary for complex, resilient Pliocene aquatic biodiversity. These revolutionary findings fundamentally alter our historical narrative, establishing the Shivaliks as a vital, ancient cradle. Ultimately, this discovery not only deepens our understanding of India’s geological evolution but also highlights the dynamic interplay between climate, landscape, and biodiversity over millions of years.Otoliths are tiny pieces of the inner ear in a fish that contain calcium carbonate and are used by fish to maintain equilibrium and enhance their sense of sound. The fossils studied were recovered from the Shivalik foothills near Mohand, located on the southern slopes of the Shivalik range, and date between 4.5 and 4.8 million years ago during the Pliocene Period. This is the first time a gourami fossil (Trichogaster fasciata) has been found in India and the second globally recorded instance of a gourami fossil, following a previous discovery in Sumatra, Indonesia. In addition to the gourami, fossils of snakehead (Channa sp.) and goby (Gobiidae indeterminate) fossils were also found as a result of sieving approximately 500 kilograms of bulk sediment collected during the 2024 field season in search of these microscopic remains.Scientists are able to accurately reconstruct the ancient climate and environment of the Himalayan foothills by using certain types of fish. The gourami is from the Osphronemidae family and generally prefers calm, still waters for spawning. Therefore, 4.5 million years ago, there existed stable, lentic freshwater ecosystems in this area instead of fast-flowing river systems. The presence of an ambush predator (the snakehead) and smaller prey (such as gobies) shows that this aquatic food chain was structured and functioning properly. The structure of these aquatic food chains indicates that the ancient water bodies were surrounded by heavily vegetated areas, providing a stable habitat, which is in stark contrast to the previously held view that the Pliocene Shivaliks were primarily terrestrial.The collaborative effort of many institutions has resulted in this discovery, which has been scientifically verified via the peer-reviewed journal Palaeobiodiversity and Paleoenvironments published by Springer Nature. The title of the study is ‘Otoliths of the Pliocene from Northwest India indicate the first osphronemid fossils and the structure of a Himalayan freshwater ecosystem in the Himalayas,’ with Dr Ningthoujam Premjit Singh of the Wadia Institute of Himalayan Geology (WIHG) leading the way. Contributing to the multi-institutional analysis were scientists from Doon University, Panjab University, the Academy of Scientific and Innovative Research at Ghaziabad, and the Biodiversity Research Centre (BRC) of Taiwan.