Incertae sedis

From Palaeos.org

(abbreviation i. s.) From Latin "of uncertain seating", incertae sedis is a term used in taxonomy and phylogenetics to indicate a taxon with an uncertain position. For instance, Myxozoa might be referred to as Animalia incertae sedis. This uncertainty may exist on two levels - it may be uncertain whether the organism is truly a member of the higher taxon, or it may be reasonably certain that the organism does belong to the taxon, but its phylogenetic position relative to other members of the taxon might be problematic. Some authors restrict the use of incertae sedis to the first level of uncertainty, and refer to the second by the phrase sedis mutabilis (Latin "of changeable seating").

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CKT061106