New and revised small shelly fossil record from the lower Cambrian of northern Iran

Small shelly fossils (SSFs) are highly informative of the ‘Cambrian explosion’. Their palaeobiodiversity has been documented from lower Cambrian deposits worldwide but it remains elusive in areas such as Iran, despite this region occupying a critical position on north-western Gondwana margin during early Cambrian. This new study SSFs northern Iran provides large dataset understudied area. We revise micropalaeontological signal Soltanieh Formation Alborz Mountains and introduce novel data overlying Barut Formations Mountains. The new, solid taxonomic stratigraphic SSF enable us to distinguish two successive microfaunal assemblages. first occurs is dominated by anabaritids (Anabarites trisulcatus, A. ex gr. tristichus, dalirense sp. nov., Cambrotubulus decurvatus) along with protoconodonts (Protohertzina anabarica P. unguliformis), maikhanellids (Maikhanella multa, Purella squamulosa sp.), Aetholicopalla adnata, indeterminate cones irregular tubes. second assemblage, Formation, diverse assemblage molluscs (Oelandiella korobkovi cap-shaped morphotypes). Siphogonuchitid sclerites also occur both assemblages characteristic Terreneuvian. Our enables assess sequence faunal change Ediacaran–Cambrian transition; contrast tube–sclerite–brachiopod succession presented literature, Iranian fauna changes one tubes sclerites, sclerites.