Extended Data Fig. 1: Sedimentological log of the Castle Bank locality, and distribution of exceptional preservation.

a, log of the Castle Bank quarry showing lithological sequence and notes on occurrence of different faunal assemblages; b, ecological log of the two-metre-thick interval of exceptional preservation, showing changing proportions of the graptolite Didymograptus murchisoni to the phosphatic brachiopod Apatobolus micula within the sequence, and correlation with extensive occurrence of soft-tissue preservation (concentrations of graptolites represent generally slower deposition); c, lithological log of the 20-cm-thick interval with Burgess Shale-type preservation, showing higher frequency of event beds (darker grey lenses and layers) that contain Burgess Shale-type preservation; d, polished vertical section through an event bed at level A3, with scale bar 1 mm.