Lower Darriwilian radiolarians from the Argentine Precordillera

The first radiolarians discovered in the Ordovician of the Argentinian Precordillera are reported. The material is associated with conodonts indicating the upper part of the Lenodus variabilis Biozone (Lower Darriwilian, Da 1-2). The low diversity radiolarian fauna shows similarities with Middle Ordovician radiolarians from the Akzhal Mountains of Kazakhstan. However, it close comparison is difficult clue to the poor preservation of the material, in which internal structures of the radiolarian tests are not preserved. (C) 2008 Elsevier Masson SAS. All rights reserved.