<p>Microbially Induced Sedimentary Structures (MISS) record the feedback between microbial mats and physical sedimentary processes, yet their palaeoenvironmental interpretation requires process-based constraints. In this study, we compare MISS preserved in late Ediacaran heterolithic deposits of the Cerro Negro Formation (Tandilia System, Argentina) with mat-influenced surfaces from a modern coastal-flat at Paso Seco (northern Patagonia) to link recurring structures to depositional and early preservation pathways. At Paso Seco, ripples and sand sheets form during storm flooding. During subsequent quiescence and exposure, cohesive microbial mats develop rapidly, trapping and binding fine-grained sediments, draping ripple troughs, and generating wrinkle textures, low-relief domes and bulges, and mat-controlled modification of desiccation cracks. Comparable suites of MISS occur on event-deposited sandy substrates in the Cerro Negro Formation and are consistently associated with sharp bounding contacts and local deformation, as well as relief preservation on bed tops. This indicates repeated alternation between energetic deposition and mat-mediated surface stabilisation. These observations support the idea that deposition at the Ediacaran site occurred on very shallow coastal-flats that were subject to episodic inundation and exposure. They also show that apparent change in grain-size and the preservation of delicate bedforms in MISS-bearing intervals can be influenced by microbial biostabilisation and should not be interpreted as switches in hydrodynamic energy alone. Overall, modern-fossil comparison strengthens the palaeoenvironmental significance of MISS and refines the interpretation of coastal-flat dynamics in the terminal Neoproterozoic.</p> Graphical abstract <p></p>