Formation: St. Louis Formation
Location: St. Louis, Missouri
Size: Plate is 4.8 inches across
This is a very nice 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 three 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 unusual. The echinoids display well on the large, natural plate of matrix that also has an urchin on the back side! This is a very rare multiple example of Mississippian echinoids from the St. Louis Formation.
This fossil was collected and obtained legally, and is also being sold legally.
A Certificate of Authenticity from EXTINCTIONS is included with this specimen.