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Free Swimming Crinoid Fossils
Crinoid fossils known as Pentacrinites have been found attached to wood by long stems in small colonies. More recent crinoids related to Pentacrinites live on rocks and are attached with a shorter stem. The vast majority of modern crinoids have evolved to be stem-less and can swim around freely. Some of the free-swimming ancestors of these crinoids are the Marsupitsa, Saccocoma and Uintacrinus crinoid fossils. These free-swimming crinoid fossils have been discovered in the Niobrara chalk of Kansas and the Solnhofen limestone of Solnhofen Germany. The Niobrara chalk of Kansas has many free-swimming Uintacrinus crinoid fossils dated back to the Cretaceous. The Solnhofen limestone in Solnhofen Germany has many Pterocoma crinoid fossils dated back to the Jurassic.
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