Crinoid

Euonychocrinus simplex

• Pennsylvanian
• LaSalle Limestone, Bond Formation
• Pontiac, Illinois, USA

Size: 4 cm across

This crinoid is one of two unusual Flexible species found in the Pontiac crinoid fauna and closely-related to the familiar Mississippian flexibles such as Taxocrinus. Its most interesting feature is the secondary ramules given off by the tertibrachials, which form a biendotomous branching pattern in the upper-half of the crown.