Crinoid

Onychocrinus grandis

• Mississippian
• Fort Payne Formation
• Campbellsville, Kentucky, USA

Size: 15 cm across the arms

A massive flexible crinoid whose preserved crown width reaches ~15 cm across. Based on an assessment by William Ausich, this specimen most closely resembles Onychocrinus grandis described from the Fort Payne Formation in size and appearance. However, unlike the description of O. grandis, this specimen appears to have four primibrachials instead of three, and the first few secundibrachials remain conjoined and then branch thereafter, before any of the tertibrachials.

Addendum: Forest Gahn agrees with the identification of Onychocrinus grandis.