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Figure 7. Generic diversity of crinoids through the Phanerozoic showing
the relative proportions of taxa possessing locomotory traits
(red) and those lacking such traits (black). Locomotory traits
include muscular arm articulations with a well-developed fulcral
ridge, fulcrum-bearing cirri distributed along the length of the
stalk, absence of a cementing or root-like mode of attachment:
for the Paleozoic, this includes only some cladid genera, while
for the Mesozoic and Cenozoic, the comatulids, isocrinids, and
holocrinids. Generic data from Sepkoski
(2002) and Webster
(2003).
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