Aethocrinus moorei Ubaghs, n. gen., n. sp., le plus ancien crinoide dicyclique connu

Aethocrinus moorei UBAGHS, n. gen., n. sp.(Lower Ordovician, France) is the oldest known dicyclic crinoid.It is a cladid inadunate of the suborder Dendrocrinina and the nominate genus of a new family, Aethocrinidae.It shows, along with many primitive characters, two very unusual features: the pentameres of its quinquepartite stem have the same orientation as the infrabasals, and its radiais are not in a line with the first brachials but alternate with them.It yields significant information on several important morphological problems and on the origin of crinoids.It does not support the derivation of Asterozoa from primitive crinoids.