Fig. 7
From: Developmental transformations in Jurassic driftwood crinoids
Convergent lineages reflect similar functional adaptations (e.g., peramorphic enlargement and adhesive integration of filter fans) as well as specific fabricational constraints. The encrinid Traumatocrinus resembles isocrinid driftwood dwellers; but it had branching ramuli and non-cirrated stems. In Ctenocrinus, ramuli are ectotomous and radial support is enhanced by fusion, rather than adhesive coupling, of arms. In Scyphocrinites, suspended from a self-made root buoy, arms continued to branch isotomously throughout. (Modified from Seilacher and Hauff 2004; all scales 5 mm)