Detailed Crawfordsville Crinoid and Ophiuroid Starfish Association

Agaricocrinus americanus

Family Coelocrinidae

Onychaster flexilis

Family Ophiuroidea

Geological Time: Lower Mississippian Osagean Stage

Size (25.4 mm = 1 inch): Agaricocrinus americanus crown: 70 mm long by 58 mm wide; stem: 25 mm Brittlestar: 45 mm across (as exposed) on a 70 mm by 128 mm matrix.

Fossil Site: Crawfordsville, Indiana Famous Crawfordsville Crinoids

Onychaster flexilis Crawfordsville CrinoidDescription: Well-preserved example of a crinoid of the Family Coelocrinidae Agaricocrinus americanus, The crinoid is very three-dimensional in aspect, with preservation of the fine pinnules quite evident. This is a fine example of the variety of diverse crinoids to be found in the Crawfordsville deposits. Note that some of the arms of the crinoid can be seen on the reverse side as well. The other Echinoderm is a member of the Ophiuroidea or Brittlestars known as Onychaster flexilis that is securely nestled amongst the arms of the crinoid. Intact starfish are rarely found. Studies have shown modern examples to fall apart within 24 hours of death if not rapidly buried. This particular type of starfish is often found in association with crinoids with which they lived symbiotically. Here is a unique opportunity to add a pair of fine Echinoderms to your collection.

click fossil pictures to enlarge

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