Procaryotic Genera Domain "Archaea" Woese et al. 1990 Phylum Euryarchaeota Garrity and Holt 2001 Class Thermococci Zillig and Reysenbach 2001 [monotypic] see Class Thermococci Zillig and Reysenbach 2002 Order Thermococcalesᵀ Zillig 1988 [monotypic] Family Thermococcaceae Zillig 1988 Genus Palaeococcus Takai et al. 2000