Encrinus Liliiformis With Markup

''Encrinus'' is an extinct genus of crinoids, and "one of the most famous". It lived during the Late Silurian-Late Triassic, and its fossils have been found in Europe.

History

Fossils of ''Encrinus'' went by several names in Germany before the establishment of modern paleontology. In Lower Saxony, they were called ''Sonnenräder'' ("sun wheels"), while in Thuringia and Hesse they were called ''Bonifatiuspfennige'' ("Saint Boniface's pennies"). In southwestern Germany, they went by ''Hexengeld'' ("witches' money"). The animal was correctly reconstructed for the first time in 1729, although various parts of the animal had been described before that.

''Encrinus'' was described in 1764 by Johann Gerhard Reinhard Andreae. It was assigned to the order Encrinida by Jack Sepkoski in 2002.

Description

''Encrinus'' possessed a large cup- or crown-like structure at the top of its body, which has been described as resembling "an unopened tulip." This "cup" could be between and long. The structure displayed "five-fold symmetry" and had a slightly Wikt:concave, concave base. It bore ten arms (although in some species, such as ''E. carnallis'', it bore 20), which in turn bore many small branches (pinnules). When opened, the arms and pinnules formed a kind of "feeding fan", used to catch prey such as plankton. "Microscopic interpinnular channels" suggest that ''Encrinus'' may have been an active filter feeder, creating its own currents by beating its Cilium, cilia. It is known that the arms could shut tightly in life (most ''Encrinus'' fossils are found in this position), but it is difficult to estimate the greatest angle at which they could open. It is possible that specimens recorded as being widest open demonstrate the normal angle of opening in life. A tegmen ("small leathery dome") covered the mouth and topped the cup. Any particles of food that the animal caught would be passed down the arms and below the tegmen via grooves, eventually leading to cilia, which in turn led to the mouth. When viewed from above, the stem was circular in shape. Large and small wikt:ossicle, ossicles covered the stem, creating a pattern of frequent small ossicles sandwiched between the large ones. The stem did not possess any wikt:cirrus, cirri, and may have been held in place by roots of some sort. The breakage of the stem during the animal's life was a common occurrence, and it often survived long enough to form a new end on its shortened stem. Being from the Middle Triassic, ''Encrinus'' is the last known from its group of crinoids, as most others died out during the Permian–Triassic extinction event.

See also

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References

External links

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{{Taxonbar, from=Q3725079

Prehistoric crinoid genera
Triassic crinoids
Middle Triassic animals of Europe