Form and function of the stem in a pseudoplanktonic crinoid (Seirocrinus)

The position of crowns and stems in the rock indicates that Seirocrinus subangularis lived attached to floating logs in spite of its unusual size. The distribution of weight and flexibility along its stem is inverse to most other crinoids, but corresponds to the assumed habitat. A few general growth gradients seem to control this and other adaptive modifications of the crinoid stems