Ammonite zones, subzones, and horizons for the NW-European Toarcian according to different authors. 1) Dean et al. 1961; Howarth 1978. 2) Page 2003, 2004. 3) Knitter and Ohmert 1983; Riegraf et al. 1984; Riegraf 1985a; Ohmert et al. 1996; Cresta et al. 2001. 4) Gabilly 1976a; Elmi et al. 1997). Note that Pleydellia (Walkericeras) lugdunensis Elmi & Rulleau, 1997 is considered by Di Cencio and Weis (2020) as junior synonym of P. (W.) pseudolotharingicum Maubeuge, 1950, so that the subzone and horizon is termed accordingly.