Name:
Archaeocidaris illinoisensis Age: Mississippian Formation: St. Louis Formation Location: St. Louis, Missouri Size: Plate is 3.9 inches across This specimen is not for sale Click here for similar specimens that are for sale
This is a very rare and important find. It is a plate of three Archaeocidaris illinoisensis from the Mississippian of St. Louis. Fossil echinoids from the St. Louis area are famous around the world and have been extremely sought-after by collectors for decades. These spiny urchins are larger than the Lepidocidaris found in the Mississippian Warsaw Formation, and are OLDER than the Pennsylvanian Archaeocidaris from Texas. These urchins themselves are complete with MANY barbed spines still intact. Most of the types of urchins from this site have smooth spines (there are three species!), and ones with the barbed spines are really cool. The echinoids display very well on the large plate of limestone. This is a very nice multiple example of Mississippian echinoids from the St. Louis Formation.