Nearshore environments before the evolution of land plants

•A pre-vegetation beach-barrier system is documented from the Tonian Burra Group, South Australia. Specific environments include low-energy fine-grained tidal flats, lagoons, tidal inlets, and beach barriers.•Example facies models are provided to aid in recognition of pre-vegetation nearshore environments.•Vegetation is not necessary for mud accumulation.•Muddy tidal flats (both siliciclastic and mixed carbonate-siliciclastic) are a common environment type before plants evolve.•Pre-vegetation beach-barrier systems can be stable, much like beach-barrier systems backed by peat.