prokaryotes - bacteria see Domain Bacteria Woese et al. 1990 Domain "Archaea" Woese et al. 1990 Phylum "Euryarchaeota" Garrity and Holt 2001 Class Thermococci Zillig and Reysenbach 2002 [monotypic] Order Thermococcales Zillig 1988 [monotypic] Family Thermococcaceae Zillig 1988 Genus Pyrococcus Fiala and Stetter 1986