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Name:
See Description
Age: Mississippian
Formation: Edwardsville Formation
Location: Crawfordsville, Indiana
Size: Plate is 7.2" X 8.5"
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This is a wonderful plate of crinoids from the famous Mississippian layers near Crawfordsville, Indiana. There are four crinoids of three different types on this plate. An excellent Macrocrinus mundulus is positioned in the center of the slab. This camerate crinoid has a very robust cup composed of many plates and long, unbranching, biserial arms. The arms are complete to the very tips, and the fine pinnulation is beautifully displayed. The slender anal tube extends way above the tops of the arms, and an extremely long stem is still tightly attached and aesthetically curved on the plate. Two examples of Agaricocrinus splendens are located near the Macrocrinus crown and also toward the distal end of the stem. These crinoids have a very flat-bottomed cup with stout, biserial arms. The plate structure of these crinoids is clearly defined. An extremely unusual Dizygocrinus sp. is located in the upper right portion of the slab. This crinoid exhibits incredible detail - the pinnulation of the arms is outstanding. A Platyceras gastropod is adhered to the tegmen of the crinoid! This gastropod lived off the excrement produced by the crinoid, and, in doing so, cleaned up the surrounding environment so the crinoid could keep living. This is a true symbiotic relationship. We have never seen a Platyceras associated with this particular genus of crinoid before. All of the fossils are quite 3-dimensional and are totally natural to the plate - none of the specimens have been composited or ''added on''. The echinoderms are well presented on the rounded rectangular, unbroken plate of siltstone. This is a very displayable plate of crinoids from this renowned site.
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