Crinoid

Metacromyocrinus sp.

• Pennsylvanian
• Pumpkin Creek Limestone, Dornick Hills Group
• Oil Creek Outcrop, Johnston County, Oklahoma, USA

Size: 4.5 cm across

This specimen was originally labeled Ethelocrinus sp. presumably on account of the prominent pustular calyx ornamentation. However, according to Peter Holterhoff, Ethelocrinus has a significant basal concavity formed primarily by incurving basal plates. I believe this specimen is more consistent with the definition of Metacromyocrinus, which has likewise coarse pustular ornamentation but a flat base with no basal concavity.