Ichnofossils from the Middle Bhuban Unit, Bhuban Formation of Pachhy Lokah near Maubawk, Siaha District, Mizoram, India

Trace fossils provide us with indirect evidence of life in the past, such as the foot prints, tracks, burrows, borings and feces left behind by animals rather than the preserved remains of the body of the actual animal itself. These imprints give palaeontologies clues with evidence of the activities of ancient animals, something body fossils simply cannot do. The Middle Bhuban rocks of Bhuban Formation are well exposed in the study area comprising sandstone, siltstone, shales and their admixtures. The grey sandstone unit exposed at Pachhy Lokah, Siaha is marked by well-preserved trace fossils comprising a total of eleven ichnospecies belonging to seven ichnogenera have been identified, namely: Katbergia isp., Laevicyclus mongraensis, Ophiomorpha nodosa, Ophiomorpha borneensis, Palaeophycus alternatus, Palaeophycus heberti, Palaeophycus striatus, Phycodes curvipalmatum, Psilonichnus upsilon, Psilonichnus isp. and Skolithos verticalis. Thus, it can be inferred from the presence of ichnofossils, that the studied successions of Bhuban Formation, Surma Group of Mizoram were deposited under sandy shifting substrate and high energy conditions in foreshore to unconsolidated, poorly sorted soft substrate and low energy condition in shoreface/offshore zone of shallow marine environment with occasion storm events.