Lower Devonian crinoid
The Edriocrinus measures 18 mm in diameter and about 2 mm thick at the thinnest
point. The six projections are about 2 mm high measured from the upper surface.
Basal plates of this stemless crinoid. All the other plates are missing
but the specimens nicely illustrate the way the juvenile crinoid found
a hard object (in this case brachiopods) as a substrate on which to
grow and keep above the mud on the sea floor. The mature specimens
obviously completely outgrew the size of their host and incorporated them
into the basal plate. The Edriocrinus dispansus is not a common crinoid.
Edriocrinus dispansus 3rd specimen
Special thanks to Bill Rushlau for donating the pictures
of these fossils he found in Oklahoma.
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