* Dotted horizontal line indicate they may be polyphyletic
1. Crenarchaeota
2. Euryarchaeota
Reference
Gribaldo, S. & Brochier-Armanet, C. (2006) The origin and evolution of Archaea: A state of the art. Philos. Trans. R. Soc. Lond., B, Biol. Sci.361: 1007-1022.