conducted that does not include a certain taxon, the authors might choose to label the taxon incertae sedis instead of guessing its placement. This is particularly common when molecular phylogenies are generated, since tissue for many rare organisms is hard to obtain. It is also a common scenario when fossil taxa are included, since many fossils are defined based on partial information. For example, if the phylogeny was constructed using soft tissue and vertebrae as principal characters and the taxon in question is only known from a single tooth, it would be necessary to label it incertae sedis. Controversy If conflicting results exist or if there is not a consensus among researchers as to how a taxon relates to other organisms, it may be listed as incertae sedis until the conflict is resolved. Other ways of denoting uncertainty Uncertain taxonomic assigations of other degrees may be denoted using the 'cf.' (before a taxon name) and '?' (after a taxon name) specifiers. In zoological nomenclature In zoological nomenclature, "incertae sedis" is not a nomenclatural term at all per se, but is used by taxonomists in their classifications to mean "of uncertain taxonomic position".Glossary In botany, a name is not validly published if it is not accepted by the author in the same publication.Article 36.1 In zoology, a name proposed conditionally may be available under certain conditions.Articles 11 and 15 For uncertainties at lower levels, some authors have proposed a system of "open nomenclature", suggesting that question marks be used to denote a questionable assignment. For example, if a new species was given the specific epithet album by Anton and attributed with uncertainty to Agenus, it could be denoted "Agenus? album Anton (?Anton)"; the "(?Anton)" indicates the author that assigned the question mark. So if Anton described Agenus album, and Bruno called the assignment into doubt, this could be denoted "Agenus? album (Anton) (?Bruno)", with the parentheses around Anton because the original assignment (to Agenus) was modified (to Agenus?) by Bruno. This practice is not included in the International Code of Zoological Nomenclature, and is used only by paleontologists. See also Glossary of scientific naming Nomen dubium, a name of unknown or doubtful application Species inquirenda, a species that in the opinion of the taxonomist requires further investigation Wastebasket taxon Sui generis (biology) Unclassified language References External links Biological nomenclature Taxonomy (biology) Zoological nomenclature