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 a very interesting 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. The unusual 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 Strimple erected an entirely new family (Clathrocrinidae) to accomodate it.

What is so interesting about this Clathrocrinus is that it appears to be undescribed/new from the Winchell Formation In the literature there are three formally-described species: C. clathratus and C. clinatus from the Pennsylvanian-Missourian of Illinois, and C. grileyi from the Pennsylvanian-Atokan of Oklahoma. 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. 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.