Crinoid

n. gen. n. sp.

• Permian
• Moran Formation
• Woodson, Texas, USA

Size: 9 cm crown

This is a Permian-aged crinoid crown from Texas and one of my most unusual fossils. According to Peter Holterhoff the upflared infrabasal plates and resulting urn-like calyx suggest assignment to the genus Ulocrinus. However, according to Georgy Mirantsev the 16 biserial arms (with four arms on the A, C and D rays) suggest closer affinity to the genus Parulocrinus. Overall this is quite an odd specimen that exhibits a combination of traits from both genera. Dr. Holterhoff believes it to have evolved either from Ulocrinus (which has 10 biserial arms) by developing >10 arms, or from a 16-armed Cromyocrinid with a typically flat-to-concave base by reverting to a "primitive" urn-like calyx. In any case it does not seem to fit any preexisting definitions and appears to be new genus of Permian crinoid. One might informally call it something like "Neoulocrinus", given the crinoid's affinities and young age in relation to them.