Search results
Results from the WOW.Com Content Network
Pentacrinites are commonly found in the Pentacrinites Bed of the Early Jurassic (Lower Lias) of Lyme Regis, Dorset, England. [2] Pentacrinites can be recognized by the extensions (or cirri) all around the stem, which are long, unbranching, and of increasing length further down, the very small cup and 5 long freely branching arms.
In this fossil-rich bed have been found the fossils of sixty species of crinoid, distributed among more than forty genera. It is thought that the various species had different length stalks so that they could capture plankton drifting past at various heights above the substrate. The fossil beds were formed at a time when the seabed was much ...
Articulated crinoid fossils are relatively rare, but disarticulated columnals are quite common in the fossil record. They may be extracted from their matrix (often limestone) or, in the case of exposures in coastal cliffs, they can sometimes be found washed out of the matrix and deposited on the foreshore, as if from the sea.
The numerous calcareous plates make up the bulk of the crinoid, with only a small percentage of soft tissue. These ossicles fossilise well and there are beds of limestone dating from the Lower Carboniferous around Clitheroe, England, formed almost exclusively from a diverse fauna of crinoid fossils. [15] Stalked crinoid drawn by Ernst Haeckel
An Indian bead in Indiana gravel. Indian bead is a colloquial American term for a fossilized stem segment of a columnal crinoid, a marine echinoderm of the class Crinoidea. . The fossils, generally a centimeter or less in diameter, tend to be cylindrical with a small hole (either open or filled) along the axis and can resemble unstrung be
Articulata are a subclass or superorder within the class Crinoidea, including all living crinoid species. They are commonly known as sea lilies (stalked crinoids) or feather stars (unstalked crinoids). The Articulata are differentiated from the extinct subclasses by their lack of an anal plate in the adult stage and the presence of an ...
Flexible fossils are very rare in the Ordovician (the most common taxa being Cupulocrinus and Protaxocrinus), but the Late Ordovician appears to have been an interval of rapid diversification for the group. [3] Major traits of Flexibilia include: [1] [4] Three infrabasal plates (in contrast to the five found in other dicyclic crinoids).
Fossil crinoid. This list of crinoid genera is an attempt to create a comprehensive listing of all genera that have ever been considered to be crinoids, excluding purely vernacular terms.