1. division Carboniferous (gymnosperms and modern pteridophytes)
2. Jurassic and possibly Late Triassic (angiosperms) Vakhrameev et al. (1978) Behrensmeyer et al. (1992) DiMichele & Aronson (1992) Sytsma & Baum (1996) and Krassilov (1997)
3. ordinal levels Permian Triassic (modern gymnosperm taxa and
4. Pteridophyte taxa) and Cretaceous (angiosperm taxa) Vakhrameev et al. (1978) Behrensmeyer et al. (1992) DiMichele & Aronson (1992) Sytsma & Baum (1996) Krassilov (1997) Magallo n et al. (1999) and Wing (2001)
5. family ¢rst half of Tertiary (60^35 Myr before present) then