Crinoid

Clathrocrinus clathratus

• Pennsylvanian
• LaSalle Limestone Member, Bond Formation
• Pontiac/Ocoya, Illinois, USA

Size: 3.5 cm crown

This is surely one of the most bizzare and beautiful crinoids found in the LaSalle Limestone. The brachials of C. clathratus are extraordinarily elongated and articulate with each other at nearly 90-degree angles. As a result, the arms form prominent zig-zag patterns which overall give the crown a cage-like (or "trellis"-like, as Strimple described) appearance (Strimple & Moore 1971). Evidently one of the more extreme approaches taken by the rising cladids in pursuing various filter-feeding niches.