Fig. 11

Habitat adaptation. From Early to Late Triassic times, four subsequent crinoid associations can be identified (see also Fig. 1), which are characterized by an increasing diversity of niches. Niche adaptation caused a strong morphological change of overall size, cup, filtration fan, stem, and attachment structures. Convergent development occurred among different clades depending on the niches. The basic type was the holocrinid attachment by cirri to either hard or soft bottoms; this type remained most successful among isocrinids until today (1, 2). Stems with stout prop-like cirri are to be found in the poorly known Eckicrinus (3). The holdfast-attached encrinids settled on shells (5), on hardgrounds (6) and acted as frame builders in small bioherms (4). Their small size allowed Dadocrinus to incrust mudsticking bivalves and thus to settle on softgrounds (7). In late Ladinian/early Carnian times two lineages led to a pelagic life: the traumatocrinids by settling on driftwood (8), and the somphocrinids by planktonic drifting (9). Due to the “Mid Carnian Wet Intermezzo”, the entire order Encrinida became extinct, and their niches were re-occupied by millericrinids (4, 5) and by the pseudoplanktonic pentacrinitids (10), respectively. As a new niche, the eleutherozoic lifestyle of the actively swimming feather stars was added by the paracomatulids and the eocomatulids (11). The Norian/Rhaetian crinoid association (4) persisted until Middle Jurassic times, in its fundamental parts until today