Sprinkle, James Department of Geological Sciences, University of Texas, Austin, Texas.
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A medium-sized class of extinct blastozoan echinoderms containing about 17–19 genera, ranging from the late Early Ordovician to the Early Silurian throughout North America and in northern Europe. Their maximum standing diversity (13 genera) occurred in the early Late Ordovician, when paracrinoids were especially common in eastern and central North America.
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