ABSTRACT
Modem stalked crinoids show heteroehronic gradients closely linked to ecology and biogeography. Changes in morphology of the different functional units through ontogeny provide a wide range of gradual variations. We discuss here the level of organization of morphological characters at different scales in the ontogenic pattern. Crinoid morphology appears to be the result of a mosaic of ossicule heterochronies which develops through space and time. Using data from arms and stalk, Guillecrinus is the most peramorphic genus, and in pentacrinid crinoids Metacrinus is the most peramorphic and Diplocrinus the most pedomorphic. Comparisons with the fossil record suggest the importance of pedomorphic processes in crinoid evolution. After discussion, it appears that the consequences of our study in terms of phylogeny and taxonomy are frequently incompatible with the cladistic interpretation given by Simms (1988).
