Fig. 15 in Revision of the flexible crinoid genus Ammonicrinus and a new hypothesis on its life mode

Fig. 15. Schematic sketches of different LCEE of the mesistele in uncoiled (above) and coiled positions (below), indicating evolution of perfecting the crown−encasing in coiled position by modifying the extensions form Emsian to Givetian. A. Lateral view of Ammonicrinus kerdreoletensis Le Menn and Jaouen, 2003, showing similar shaped columnals with very short LCEE; thus, the crown is laterally nearly unprotected in coiled position. B. Lateral view of Ammonicrinus wanneri Springer, 1926, with lengthened LCEE of the similar shaped columnals, which lattice−like guarded the crown in coiled position. C. Lateral view of Ammonicrinus sulcatus Kongiel, 1958, showing smaller columnals of the mesistele, which are interconnected with longer ones and afford lateral density of the coiled stem. D. Lateral view of Ammonicrinus doliiformis Wolburg, 1938a (for 1937), showing regularly or irregularly arranged columnals with longer and shorter LCEE, which were interconnected with several columnals showing broadened convex and concave extensions that could interlock in coiled position.