Crinoid

Cupulocrinus crossmani

• Ordovician
• Dunleith Formation, Galena Group
• Iowa or Minnesota, USA

Size: 2.5 cm across the arms

Identification based on "Brower, J. 1992. Cupulocrinid Crinoids from the Middle Ordovician (Galena Group, Dunleith Formation) of Northern Iowa and Southern Minnesota"; confirmed by William Ausich.

Traits consistent with the description are: the anal X is "hexagonal, nearly equidimensional", the anal tube is "elongate" and "dominated by (a) large median row of large, rectangular, approximately equidimensional plates", and the column is made of a mixture of thin and thick nodose columnals (Brower 1992).