Crinoid Holdfasts
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The Crinoid Holdfasts we have for sale are Eucalyptocrinus. Now extinct, their fossils are from the middle Silurian Period and are about 424 million years old. They were found in the Waldron Shale Formation, Shelby County, Indiana.
The holdfast is a root-like structure that the crinoid used to anchor itself to the sea floor. (See illustration at the bottom of the page.)
The holdfast is a root-like structure that the crinoid used to anchor itself to the sea floor. (See illustration at the bottom of the page.)
The Eucalyptocrinus Timeline
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Paleozoic Era
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Mesozoic Era
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Cambrian Period
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Ordovician Period
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Silurian Period
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Devonian Period
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Carboniferous Period
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Permian Period
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Triassic Period
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Jurssic Period
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Cretaceous Period
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Crinoids, sometimes called sea lilies, are animals that look much like plants with parts that are analagous to roots, stems, and flowers. In crinoids they are the holdfast, stalk and crown. While Eucalyptocrinus is extinct there are still crinoids in todays oceans.
Scientist can study these living crinois to help understand how crinoids lived in times gone by.
The holdfast is made up of cirri that wrap around a rock or other object on the sea floor. In environments with a rocky seafloor the cirri can be robust. If the environment is soft sediment the cirri tend to be slender.The stalked crinoids were usually stationary but crinoids could actually move if they needed to, although very slowly. One living crinoid was recorded moving at about 2 feet per hour along the seafloor.
