Multiple routes to mass accumulations of clypeasteroid echinoids: A comparative analysis of Miocene echinoid beds of Sardinia

► Three Miocene sand dollar assemblages of Sardinia were analyzed in detail. ► A low taxonomic diversity with prevalence of Amphiope and Parascutella was recorded. ► Age spectrum, taphonomic signatures and sedimentary fabric widely differ. ► Three different genetic mechanisms in the shoreface environment can be inferred. ► Multiple in situ reworking, storm deposition and autochthonous accumulation occurred.