Fig. 1

Triassic crinoid diversification. Genus and higher taxonomic units are based on Hess (in press). Numbers indicate valid species as referenced in the Appendix. Artefacts may originate from the limited fossil record. Conservation Lagerstätten with diverse crinoid palaeocommunities such as the Anisian Muschelkalk or the late Ladinian/early Carnian Cassian Formation may be overrepresented compared to early Ladinian or early Norian sediments that have yielded relatively few crinoids. Moreover, the diversity of Isocrinidae recorded in countless nominal “Isocrinus” species based on isolated columnals (Simms 1990a, b) is certainly higher than in this chart. The species concept of Osteocrinus (ca. 15 nominal species) and of the benthic microcrinoids is also based on isolated sclerites showing minimal differences, many of which may have resulted from the etching process during preparation. In this paper 5 well characterized Osteocrinus species were selected. Nominal species attributed to the parataxonomic genus Entrochus were excluded. A distinct faunal change caused by the “Mid Carnian Wet Intermezzo” is indicated by the extinction of order Encrinida, while Isocrinida and Millericrinida persisted into the Norian and later Mesozoic. Thus, four Triassic benthic crinoid associations can be distinguished (cf. Fig. 11), (1) an Early Triassic Holocrinida association of extremely low diversity, (2) a diverse Middle Triassic Holocrinida/Encrinida association, (3) an early Late Triassic Isocrinida/Encrinida association, (4) a late Late Triassic Isocrinida/Millericrinida association. The major turnover happened in Carnian times after the overall Triassic diversity had reached its peak