Mushroom crinoid facts for kids
Agaricocrinus americanus, also known as the mushroom crinoid, is an extinct sea animal. We only know about it from its fossils. These fossils are found in the U.S. states of Indiana, Tennessee, and Kentucky. They lived a very long time ago, about 345 million years ago, during a period called the Lower Mississippian.
Quick facts for kids Mushroom crinoid |
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| Calyx with arms and pinnules | |
| Scientific classification | |
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Coelocrinidae
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| Genus: |
Agaricocrinus
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| Species: |
A. americanus
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| Binomial name | |
| Agaricocrinus americanus |
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Contents
Where We Find Mushroom Crinoid Fossils
One important place where Agaricocrinus americanus fossils are found is the Edwardsville Formation. This area is near Crawfordsville, in Montgomery County, Indiana. This fossil-rich bed has given us fossils from sixty different types of crinoids. These crinoids belong to more than forty different groups.
Scientists think that these various crinoid species had stalks of different lengths. This allowed them to catch plankton floating by at various heights above the seafloor. The fossil beds formed when the seabed was much higher than it is today. It is believed that storms buried the crinoids in sediment from nearby deltas. The soft siltstone rocks that formed make it easy to dig out the fossils. These fossils often look three-dimensional.
Other Fossil Discoveries
Other fossils of Agaricocrinus americanus have been found in similar rocks. These include areas like Whites Creek in Davidson County, Tennessee. They have also been found in Kentucky and the Fort Payne Formation. This formation is near the border between Tennessee and Kentucky.
Scientists have noticed small differences in specimens from these various places. Sometimes, new finds were thought to be new species. However, in 1997, David Meyer and William Ausich studied the Agaricocrinus group. They suggested that several other species names should actually be considered the same as Agaricocrinus americanus. A close relative, but less common, is Agaricocrinus crassus.
What Did It Look Like?
Like crinoids that are alive today, Agaricocrinus americanus was attached to a hard surface. It used a special part called a holdfast to stay in place. From this holdfast grew a flexible stalk.
On top of the stalk was a cup-shaped body called a calyx. Many feather-like arms grew from this calyx. Each arm had short branches called pinnules. From these pinnules, tiny hair-like parts called cirri reached out. These cirri helped to filter tiny bits of plankton from the water as it flowed past.
Images for kids
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Stalk and detached arms
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