Marine and non-marine palynomorphs from the Ordovician sequence of Takche Formation, Spiti, India

The palynological investigation of a sequence of the Takche Formation (Middle Ordovician–Early Silurian), Spiti region in the Tethyan Himalaya, reveals new perspectives into Ordovician micro-faunal and floral diversity, palaeoenvironments, biostratigraphy and the likely signatures about early land plants within Gondwana. The recovered palynomorph assemblage is rich in marine forms such as chitinozoans, acritarchs, melanosclerites, and scolecodonts, along with non-marine palynomorphs, which comprises possible cryptospores and phytodebris. The chitinozoan assemblage comprises genera- Belonechitina, Baltochitina, Eisenackitina and Euconochitina . Acritarch assemblage is characterised by Baltisphaeridium, Orthosphaeridium, Stelliferidium, Dactylofusa, Leiosphaeridia, Lophosphaeridium and Focusphaera . Scolecodonts’ assemblage is dominated by simple jaw elements, associated with ctenognath- and placognath-type apparatuses, of which placognath are common. The melanosclerites assemblage includes Mirachitina, Melanoporella, Eichbaumia, Melanorhachis , and Melanosteus. The non-marine palynomorphs of the putative cryptospore assemblage show semblance with the taxa Chelinospora, Didymospora, Laevolancis, Rugosphaera, Dyadospora and Segestrespora. Although preservation is generally poor and thermal maturity is high, the presence of diagnostic taxa across multiple palynological groups permits robust palaeobiological and palaeoenvironmental interpretations. The abundance of marine forms clearly reflects deposition in a distal shallow marine setting, removed from significant terrestrial influence. These findings are consistent with similar studies from comparable sequences in the region and elsewhere along the northern Gondwana. The present study not only enhances our understanding of the Ordovician biodiversity in India but also paves the way to further explore and enrich the global narrative of early plant evolution and palaeobiogeographic connectivity during the early phases of life on land from the Indian subcontinent.