Eocrinoidea

Rhopalocystis sp.mit regular and Rhipidocystis sp. with irregular paneling of the body capsule ( Ordovician ).

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The Eocrinoideen ( " primordial sea lilies " ) is an extinct genus within the tribe of echinoderms ( Echinodermata ) and perhaps with the living today sea lilies and feather stars ( Crinoidea class, subphylum Crinozoa ) distantly related. In the scheme the Eocrinoideen be summarized with about 30 genera along with the other extinct genera Cystoidea (bag lamps), Blastoidea (bud spotlight), and Paracrinoidea Parablastoidea in the subphylum Blastozoa.

The Eocrinoideen are a polyphyletic very heterogeneous group, which existed from the lower Cambrian to Silurian in the. From them the Cystoids developed in several separate lines. The Eocrinoideen also be regarded as a regular group of Paracrinoideen and Parablastoideen. It is unclear whether the similarity is due to the Crinoideen to an actual relationship, or whether it is a convergent development.

The Eocrinoideen have - like the Crinoideen - almost always sitting on a stem or anchoring organ spherical (also oval to pear-shaped ) body capsule ( theca ), consisting of tablet and forms a rigid armor. The tablets of the theca are sometimes completely unregulated, partly arranged strictly rule- bounds. There are slot-shaped openings ( Epispira ) of a presumably breathing serving pore system at the boundaries of the tablet. On the theca (mostly double-spaced ) attached unbranched brachioles, the theca is almost always attached to a stem or anchoring member at the sediment.

Way of life

The Eocrinoideen subsisted by filtered fressbare particles with their brachioles from the passing water and carried to the mouth. Almost all Eocrinoideen were - how crinoids - constantly with a stem attached to the sea floor ( sessile ).