Crinoid Fossil Info: Crinoid fossils were originally marine organisms called crinoids living in both shallow tropical seas and deeper waters during the Paleozoic era. The Mississippian is known as the Age of the Crinoids due to the abundance of fragmented crinoid fossils in the rocks. Crinoids are also referred to as feather stars or sea lilies. Crinoid fossils are called sea lilies due to their long stem and flower-like arms. Scientists classify crinoids into phylum Echinodermata and class Crinoidea. Every crinoid in class Crinoidea has a mouth on top of its body encircled by a number of arms used for eating. Even though crinoids are classified into phylum Echinodermata and are symmetrical five ways, they often have more than five arms. All crinoids are filter feeders and most crinoids only use their stem to latch on to solid objects in the earlier phases of life, releasing later to swim as adult crinoid. Most crinoid fossils found are of the plates composing the stem of the crinoid. These plates look like buttons when fossilized.
The Crinoid Fossil Record: From looking at the crinoid fossil record it is evident that the crinoids have experienced many interesting events since first appearing in the fossil record. After the first crinoids evolved they were able to quickly fill many ecological niches in a multitude of marine ecosystems. Crinoids were in competition with other echinoderms like blastoids in the Permian period. During the Permian period nearly all of the crinoids originating from the Palaeozoic disappeared from the fossil record during what is known as the Permian crisis with only a few species making it to the Triassic. Many other echinoderms competing with crinoids also disappeared at this time. With the Mesozoic era came another boom in crinoid success thanks to the development of flexible feeding arms. Overall, phylum Echinodermata has been able to adapt to many new conditions.
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| Crinoid fossils from Indiana |
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An unusal and well preserved |
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