Biodiversity of Himgir Sub-Basin, India during Late Permian: A Comprehensive Study

The Himgir sub-basin is the southwestern part of the Ib River Basin, Odisha, India. A Lower Gondwana fossil horizon was explored along the road section near Himgir Village, Sundargarh District, Odisha and plant megafossils (1002 specimens) comprising both pteridophytes and gymnosperms, four plant groups, ten genera and fifty-five species were reported. Pteridophytes (Equisetales, Sphenophyllales and Filicales) are represented by Schizoneura gondwanensis Feistmantel, 1876, equisetaceous stems, Trizygia speciosa Royle, 1839 and Neomariopteris talchirensis Maithy, 1974. Gymnosperms are represented by one plant group namely Glossopteridales (46 species Glossopteris) along with stem casts, fructifications and scale leaves. The occurrence of Late Permian floras, the lack of distinctive Dicroidium flora of the Triassic period in this assemblage, and the red bed facies (ferruginous red sandstone and ferruginous red shale) of the investigated locality reveal that the exposure belongs to Lower Kamthi Formation of Wuchiapingian to Changhsingian age. The macrofloral assemblage demonstrates a warm-humid climate with flashing rainfall and moderate light intensity. Vegetation of the studied sub-basin has also been studied to portray the palaeobiodiversity of the area.