Un cas remarquable d'epigenie chez un anopliide (Chonetacea, Brachiopoda) du Devonien de Bolivie

An exceptional preservation is described in an anopliid from the probable Lower Middle Devonian (Eifelian) of the Bolivian Altiplano. The partial epigeny of the shell by silica implies a rapid, but progressive and centripetal process which is tentatively reconstructed. The selective character of this kind of fossilization must be considered as related to the microstructure of the chonetacean shell, because it only affects the secondary transitional "fi­brous" shell.