Ammonoids nearly died out during the Permian-Triassic (PT) mass extinction (~ 252 Ma), but quickly and rather impressively recovered in less than ~ 1.5 myr during the Early Triassic (Tozer 1981a; Brayard et al. 2009a; Brayard and Bucher 2015; Fig. 7.1). Only one survivor group, a derivative of the Xenodiscaceae, is usually considered as the root-stock of all Triassic, and thus, all post-Triassic ammonoids (Kummel 1973a; Spinosa et al. 1975; Tozer 1981a, 1981b; Page 1996; Brayard et al. 2006), making post-PT ammonoids a “quasi-monophyletic” group (but see Kummel 1972; Glenister and Furnish 1981; Brayard et al. 2007a; McGowan and Smith 2007; Leonova 2011; Zakharov and Moussavi Abnavi 2013).