Archaeospicularia, new Radiolarian order; a new step for the classification of the Lower Paleozoic Radiolaria.

A new radiolarian order - Archaeospicularia - is proposed for some Lower Pa leozoic radiolarians previously considered to belong to Spumellaria and to Collodaria. It is characterized by a globular shell made of several spicule s which can be free, interlocked, or fused to formed a latticed wall. The p resent paper gives the definition of this order and proposes a first classi fication. It is supposed that the Archaeospicularia represents the oldest r adiolarian group and that in the Lower Paleozoic it gave rise to the orders Entactinaria, Albaillellaria, and probably Spumellaria by the reduction of the number of initial spicules. The origin of this order and its relations hips with other groups of organisms with siliceous skeletons are also brief ly discussed. (C) 2000 Academie des sciences / Editions scientifiques et me dicales Elsevier SAS.