Richest Late Permian floral diversities of Glossopteris flora of India and its palaeoclimatic inferences

A rich collection of plant megafossils has been studied from the Late Permian Gondwana sediments of the Lower Kamthi Formation, Talcher Basin, Odisha. The fossiliferous horizon was explored along the road section (N 20° 58′ 40″ latitude and E 84° 42′ 36″ longitude) of Hinjrida Ghati near Handapa, Angul District, Odisha. The compact, finely grained, pinkish-brown shale contains the plant fossils preserved as imprints. Thirteen hundred and thirty-seven (1337) specimens of plant megafossils, representing sixty-four (64) different species and five (5) plant groups including both gymnosperms and pteridophytes, make up the megafloral assemblage. Pteridophytes are exemplified by Equisetales (Equicetaceous stems, Schizoneura gondwanensis), Filicales (Neomariopteris hughesii, Neomariopteris talchirensis, Dizeugotheca phegopteroides), and Sphenophyllales (Trizygia speciosa). Gymnosperms are represented by Ginkgoales (Rhipidopsis gondwanensis) and Glossopteridales (54 species of Glossopteris, 2 species of Gangamopteris: G. angustifolia, G. cyclopteroids) along with stem axis and scale leaves. The assemblage has been compared with the known Late Permian assemblages of Indian Gondwana. With so many species from a Lower Gondwana exposure, this is one of the richest reports in existence. Glossopteris dominates the assemblage with thirteen hundred one (1301) specimens, with 97% of the assemblage and 54 different species. The investigated sediments are identified as belonging to the Lower Kamthi/Raniganj Formation of Late Permian (Lopingian) affinity as evidenced by the floral assemblage (Late Permian floras, the absence of typical Triassic element—Dicroidium flora), and the lithology of the fossiliferous horizon with the red bed facies (ferruginous sandstones and fine-grained pinkish-brown shales). The rich diversity of the Glossopteris in the fine sediments, along with several petiolate leaves, infers a low-energy environment during the deposition. In the Talcher Basin during the Late Permian, a temperate forest thrived due to warm weather, high humidity, intense light, strong winds, and a temperate climate.