New data on the Valanginian - Hauterivian Ammonites from the stratotypical area of Neuchatel (Swiss Jura Mountains):biostratigraphic implications.

New collections of Upper Valanginian - Lower Hauterivian ammonites yield precisions about the biostratigraphical scheme of the Lower Cretaceous in the stratotypical area of Neuchatel (Swiss Jura Mountains). Thus, Stoicoceras pitrei (BUSNARDO, 1966) from the "Calcaire roux limoniteux" is reported in the upper Saynoceras verrucosum Biozone (Karakaschiceras pronecostatum Subzone) of the Upper Valanginian. In the Lower Hauterivian, Olcostephanus (O.) variegatus PAQUIER, 1900, from the upper part of the "Marnes bleues d'Hauterive" and Saynella cf. clypeiformis (d'ORBIGNY, 1841) from the "Marnes d'Uttins" (top of the lower part of the "Pierre jaune de Neuchatel") extend greatly the range of the Lyticoceras nodosoplicatum Biozone compared to a more reduced Crioceratites loryi Biozone indicated by Saynella neocomiensis (BAUMBERGER, 1905) and a unique specimen of Crioceratites cf. gr. loryi (SARKAR, 1955) found in 1907.