India Discovers First Gourami Fossil in Siwaliks: Rare Otolith Evidence from Pliocene

Scientists have discovered freshwater fish fossils(otoliths) in the Mohand area of Saharanpur (Upper Siwaliks), Uttar Pradesh marking India’s first gourami fossil and only the second globally.

• Research Leadership: The study was led by Ningthoujam Premjit Singh of the Wadia Institute of Himalayan Geology.
• The study, published in Springer Nature records:
  • First fossil evidence of gourami (family Osphronemidae) in India
  • Only the second such record globally

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Key Findings

• Age Certainty and Stratigraphic Significance: While similar fossils have been reported from Sumatra, their exact age remains uncertain due to unclear stratigraphy; in contrast, the Mohand fossils are reliably dated to about 4.8 million years ago.

• Evidentiary Value: The fossil evidence suggests that during the Pliocene, the area had a calm, stable freshwater body surrounded by dense vegetation. This is inferred from the presence of Osphronemidae family.
  • Osphronemidae Family: It is a family that includes living gouramis, to which snakeheads, ambush predators, belong.
• First Freshwater Fish Otoliths from Pliocene (Siwaliks): The study reports the discovery of freshwater fish otoliths (ear stones used for hearing and balance) from the Pliocene deposits of the Siwalik Group in Saharanpur, marking the first such record from this period in the region.
• Discovery of Gourami Fossils: The fossils include members of the Osphronemidae (gourami family), representing the first fossil record of gouramis in India and only the second globally, with earlier findings from Sumatra lacking precise geological dating.
• Associated Fish Species: The fossil assemblage indicates the presence of gouramis, snakeheads (genus Channa), and gobies, suggesting a diverse and well-structured freshwater fish community during the Pliocene epoch.

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Significance of the Discovery

• Filling the Fossil Gap: The discovery fills a critical gap in the fossil record of the Siwalik Group, which was previously dominated by terrestrial mammalian fossils, by providing the first clear evidence of freshwater fish biodiversity in the region.
• Biogeographical Insights: The findings contribute to understanding the evolution and dispersal of Anabantoidei (labyrinth fishes such as gouramis) and establish a biogeographical linkage between South Asia and Southeast Asia, including regions like Sumatra.
• Climate and Environmental Clues: The fossil evidence indicates that the region experienced a humid climate with stable freshwater ecosystems during the Pliocene epoch, supporting diverse aquatic life.
• Significance of Rare Fossil Type: The discovery of otolith fossils, which are extremely rare in the Indian subcontinent, enhances the accuracy and reliability of species identification and palaeoenvironmental reconstruction.
• Decoding History of the Gourami family: Although only a small number of otoliths have been found, this study offers important insights into how freshwater fish were distributed in the past, including the history of the gourami family.

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