Crinoid+

1. (Crinoid) Clathrocrinus aff. C. clathratus
2. (Echinoid) Archaeocidaris brownwoodensis

• Pennsylvanian
• Winchell Formation
• Brownwood, Texas, USA

Size: 3.5 cm crown for the Clathrocrinus

1. Here is an unusual crinoid from the Pennsylvanian Winchell Formation of Brownwood, Texas. This locality is primarily known as an echinoid (urchin) lagerstatte for producing plates of spectacularly-preserved Archaeocidaris specimens, but its crinoids appear to still be undescribed. The crinoid here is almost certainly a Clathrocrinus. The bizzare zig-zag branching pattern of the ten arms is unique and different enough from all other known crinoids that an entirely new family was erected (Clathrocrinidae) to accomodate it (Strimple & Moore 1971).

In the literature there are three formally-described species of Clathrocrinus: C. clathratus and C. clinatus from the Pennsylvanian-Missourian of Illinois (Strimple & Moore 1971), and C. grileyi from the Pennsylvanian-Atokan of Oklahoma (Strimple 1975). This specimen's anal plates are consistent with the two known Missourian species, but overall the crown has features of both: broader angles of arm-branching like C. clinatus, and bulbous calyx plates with deep sutures between them like C. clathratus, though the plates aren't quite as sharp or ornate (Strimple & Moore 1971). In my opinion this Clathrocrinus may be a new species and possibly ancestral/transitional. However a paleontologist's assessment will be needed to make the ID conclusive.

Addendum: Georgy Mirantsev has confirmed the identification of this specimen as a Clathrocrinus with affinity to C. clathratus.