Diversity dynamics of post‐Palaeozoic crinoids – in quest of the factors affecting crinoid macroevolution

Following the end‐Permian biotic crisis which led to the near extinction of crinoids, this echinoderm class rebounded rapidly during the Mesozoic, resulting in forms with important morphological and behavioural novelties. However, quantitative patterns of crinoid diversity during the Mesozoic remain largely unexplored. Here, we report results of analyses of the evolutionary dynamics of post‐Palaeozoic crinoid genera spanning a time interval between 250 and 70 Myr. We show that crinoids reached their Mesozoic peak of genus‐level richness during the Late Jurassic. We also document a major reorganization of different ecological crinoid groups in the Mesozoic. More specifically, the diversity of sessile forms generally increased towards the mid‐Mesozoic but decreased significantly starting in the Cretaceous, whereas the number of motile crinoid genera increased linearly during the Mesozoic. The possible role of biotic and abiotic factors in crinoid evolution is discussed.