A Middle Ordovician Burgess Shale-type fauna from Castle Bank, Wales (UK).

Burgess Shale-type faunas are critical to our understanding of animal evolution during the Cambrian, giving an unrivalled view of the morphology of ancient organisms and the ecology of the earliest animal-dominated communities. Rare examples in Lower Ordovician strata such as the Fezouata Biota illustrate the subsequent evolution of ecosystems but only from before the main phase of the Great Ordovician Biodiversification Event. Later Ordovician Konservat-Lagerstätten are not directly comparable with the Burgess Shale-type faunas as they do not represent diverse, open-shelf communities, limiting our ability to track ecological development through the critical Ordovician biodiversification interval.