Crinoid

Cybelecrinus ladas

• Silurian
• Cybele Member, Jupiter Formation
• Anticosti Island, Quebec, Canada

Size: 6 cm crown

Anticosti Island is significant for being the only locality in the world to contain formations spanning the Ordovician-to-Silurian boundary. Hence it provides an unparalleled window into the major transitions in crinoid fauna caused by the end-Ordovician mass extinction. No doubt due to this unique geology, many crinoid genera and species are entirely endemic to Anticosti Island and not known from elsewhere. Cybelecrinus ladas is one such genus and species (and named after its unique provenance). This crinoid is characterized by its prominent sharp ray ridges that continue onto its basal plates, variable stellate/granular/smooth calyx ornamentation, and 20 slender, unbranched pinnulate free arms, as seen in this spectacular specimen.

When the genus and species Cybelecrinus ladas was newly-established in 2010 by Ausich & Cooper, no description of the distal stem or holdfast was made. From this specimen, it seems C. ladas has a "distal coil" type of holdfast similar to that of Glyptocrinus (examples in the last two photos). In this strategy, instead of developing a distinct disc or root-like attachment structure, the distal stem would simply wrap around a substrate to anchor the crinoid in place.