Devonian Conodonts from the Upper Amazon Basin, Northwestern Brazil

Abstract This is the first positive record of conodonts in the Devonian of Brazil. They occur in Late Devonian rocks of the Upper Amazon Basin (the newly redesignated Solimoes Basin) presently being explored by PETROBRAS for oil and gas. Paleozoic strata are known only from the subsurface of this basin. The fact that they are not easily correlatable with classic Siluro-Devonian lithostratigraphic units of the adjoining Middle Amazon Basin may reflect important differences in the geological evolution of each basin. The fossil material, recovered from core no. 3 of well 1-JD-1-AM, is preserved in pyritic, highly carbonaceous black shales. It consists of many isolated elements of conodont apparatuses belonging to several genera, of which Cryptotaxis (Upper Devonian, Famennian), Parapolygnathus and Hibbardella (Middle to Upper Devonian), Polygnathus (Lower Devonian to Lower Carboniferous) and Pandorinellina (Lower to Upper Devonian) were preliminarily identified.