Pleurocystites sp.
Phylum Echinodermata, Class Cystoidea, Order Rhombifera
Geological Time: Middle Ordovician
Size: Cystoid fossil is 75 mm long including 21 mm stem Matrix: 110 mm by 175 mm.
Fossil Site: Sugar River Formation, Trenton Group, Sackets Harbor, New York
Code: MMT90
Price: Sold
 Description:
This plate displays an example of the rhombiferan cystoid known
as Pleurocystites. Cystoids are relatives of the crinoids that
have oval rather than rounded calyces. They were either stalkless
or attached to a stalk much like crinoids. Their triangular pores
distinguish them from all other echinoderms. They arose during
the Late Cambrian and became extinct during the Late Devonian (~500-375
million years ago). Like all other echinoderms they typically would
disarticulate shortly after death. This one must have been quickly
buried to allow it to be preserved as you see it here preserved
in dorsal aspect. |
