This poster depicts a composite transect from the Vocontian through (Vergons -hypostratotypic section of the Hauterivian- and Angles -stratotypic section of the Barremian-) to the platform (Vivarais, Vercors, and Jura) during an interval of time spanning the Ligatus, Balearis and Ohmi zones (Late Hauterivian p.p.). It  illustrates the procedure of using assemblages of orbitolinids to identify the position of intervals time-equivalent ammonite zones in platform settings where these macrofossils are either rare or absent.