The consideration of events of marine invasion within the continental Gondwanaland in the Indian subcontinent during the Permian is often doubted due to lack of appropriate fossil record. The Permian Barren Measures Formation within the Lower Gondwana Supergroup in eastern India is considered as deposited in a fluvio-marine estuarine setting, interpreted mostly based on sedimentological signatures in terms of marine tide and wave imprints within the so-called continental fluvial deposits. Fossilized shells of marine Gastropoda genus Baylea DeKoninck, 1883, are reported here from the siltstone beds of the prodeltaic sediments of the Barren Measures Formation, West Bokaro Basin. The in-situ preservation of the marine invertebrate fossils Baylea sp. provides definite proof of marine link of the West Bokaro Basin during the Barren Measures sedimentation. The present fossil record, when combined with sedimentological attributes, clearly signifies a marine inland encroachment event during the Permian time.