incertae sedis

"Colostethus" ruthveni, a species of frog that is placed incertae sedis in the family Dendrobatidae New World vultures, such as the California condor, were placed incertae sedis within the class Aves until the recognition of the new order Cathartiformes. Plumalina plumaria Hall, 1858 (6.3 cm tall), Upper Devonian of western New York State, US. Workers usually assign this organism to the hydrozoans (phylum Cnidaria, class Hydrozoa) or the gorgonarians (phylum Cnidaria, class Anthozoa, order Gorgonaria), but it is probably safest to refer to it as incertae sedis. The varanopids, a mysterious family of tetrapods, had controversial relationships with many other land tetrapods. Paleolontologists have mostly assigned them in the past as eupelycosaurian synapsids. Others have placed them as basal neodiapsids. A compromise is to place them as Amniota incertae sedis. Incertae sedis (Latin for 'of uncertain placement') or problematica is a term used for a taxonomic group whose broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty at specific taxonomic levels is indicated by incertae familiae (of uncertain family), incerti subordinis (of uncertain suborder), incerti ordinis (of uncertain order) and similar terms.

Examples