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The term sister group is used in phylogenetic analysis, however, only groups identified in the analysis are labeled as "sister groups".. An example is birds, whose commonly cited living sister group is the crocodiles, but that is true only when discussing extant organisms; [3] [4] when other, extinct groups are considered, the relationship between birds and crocodiles appears distant.
Alternatively, the term "stem group" is sometimes used in a wider sense to cover any members of the traditional taxon falling outside the crown group. Permian synapsids like Dimetrodon or Anteosaurus are stem mammals in the wider sense but not in the narrower one. [16] Often, an (extinct) grouping is identified as belonging together.
The International Code of Phylogenetic Nomenclature, known as the PhyloCode for short, is a formal set of rules governing phylogenetic nomenclature.Its current version is specifically designed to regulate the naming of clades, leaving the governance of species names up to the rank-based nomenclature codes (ICN, ICNCP, ICNP, ICZN, ICVCN).
Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional method , by which taxon names are defined by a type , which can be a specimen or a taxon of lower rank , and a description in words. [ 1 ]
Lazarus taxon; node-based taxon; ootaxon (oospecies, etc.): a taxon known from fossil eggs; parataxon; sciotaxon a taxon known from partial evidence but believed to be identical to an orthotaxon; sister taxon; zombie taxon; polyphyletic taxon; monophyletic taxon: a taxon consisting of a common ancestor and all its lineal descendants; a clade ...
In biology, taxonomic rank (which some authors prefer to call nomenclatural rank [1] because ranking is part of nomenclature rather than taxonomy proper, according to some definitions of these terms) is the relative or absolute level of a group of organisms (a taxon) in a hierarchy that reflects evolutionary
Phylogenetic signal is a concept widely used in different ecological and evolutionary studies. [7]Among many questions that can be answered using a concept of phylogenetic signal, the most common ones are: [1]
Purely in the context of modern taxa, Lepidosauria can be considered the sister taxon to Archelosauria, which includes Testudines (turtles), Aves (birds) and Crocodilia (crocodilians). Lepidosauria is encompassed by Lepidosauromorpha, a broader group defined as all reptiles (living or extinct) closer to lepidosaurs than to archosaurs.