procaryotes Domain Archaea Woese et al. 1990 stat. inval. see Domain Archaea Woese et al. 2024 Phylum Crenarchaeota Garrity and Holt 2001 [monotypic] Class Thermoprotei Reysenbach 2001 nom. inval. see Class Thermoprotei Reysenbach 2002 Order Thermoprotealesᵀ Zillig and Stetter 1982 Family Thermoproteaceae Zillig and Stetter 1982 Genus Pyrobaculum Huber et al. 1988