With the phylogenetic classification, the taxon Labyrinthodontia has been discarded as it is a paraphyletic group without unique defining features apart from shared primitive characteristics.

The name of the taxon Apicomplexa is derived from two Latin words-apex ( top ) and complexus ( infolds )-and refers to a set of organelles in the sporozoite.

* A clade is often said to be more basal the farther away it lies from the taxon of interest.

In the latter, only taxa associated with a rank can be named, yet there are not enough ranks to name a long series of nested clades ; ranks determine the form of names, so names must in many cases change when a name is inserted into such a series ; and taxon names cannot be defined in a way that guarantees them to refer to clades.

What is more, many an individual invertebrate taxon has a greater number and variety of species than the entire subphylum Vertebrata, In fact some of the so-called invertebrata, such as the Chaetognatha and Hemichordata, are more closely related the Chordata than to other invertebrate phyla.

In referring to taxonomy of the Animalia, " invertebrata " is a term of convenience, not a taxon ; it has very little circumscriptional significance except arguably within the Chordata.

In cladistics, originating in the work of Willi Hennig, 1950 onwards, each taxon is grouped so as to include the common ancestor of the group's members ( and thus to avoid polyphyly ).

In common cladistic usage, a monophyletic group is a taxon ( group of organisms ) which forms a clade, meaning that it consists of a species and all its descendants.

Some debate is still going on if the parent taxon Nektaspida should be included in the Trilobita, or is better placed as a sister group.

It contains about 1, 000-2, 000 species of shrubs, herbs, and lianas, many of which are keystone species in their native habitat The diversification of this taxon is of interest to understanding the evolution of plants.

A taxon that is not paraphyletic or monophyletic is polyphyletic ( Greek πολύς, " many ").

The ' definition ' of a taxon is encapsulated by its description.

However, often much more information is included, like the geographic range of the taxon, ecological notes, chemistry, behavior, etc.

Biological classification is a critical step in the taxonomic process, as it informs the user as to what the relatives of the taxon are hypothesized to be.

There is some dispute as to whether Ungulata is a cladistic ( evolution-based ) group, or merely a phenetic group ( form taxon ) or folk taxon ( similar, but not necessarily related ), because not all ungulates appear as closely related as once believed.

This infraorder is a sister taxon of Lemuriformes, the lemurs.

" Turtle " may either refer to the order as a whole, or to particular Turtle which make up a form taxon that is not monophyletic.

A genus in one kingdom is allowed to bear a scientific name that is in use as a generic name ( or the name of a taxon in another rank ) in a kingdom that is governed by a different nomenclature code.

**** Dingo, most often classified as Canis lupus dingo ( sometimes considered a separate taxon )

The Eastern and Western populations are sometimes recognized as two different subspecies, the Eastern race being the nominate H. histrionicus histrionicus, and the Western race as H. h. pacificus, but there has been doubt on the validity of this taxon.

A subtle difference is sometimes made between a " living fossil " and a " Lazarus taxon ".

For example, Pachypodium can sometimes occur in prehumid vegetative zones where a taxon might find a suitable habitat on a rocky, sunny inselberg jutting above the humid canopy of the forest.

Malacostracans are sometimes contrasted with entomostracans, a name applied to all crustaceans outside the Malacostraca, and named after the obsolete taxon Entomostraca.

Types are usually physical specimens that are kept in a museum or herbarium research collection, but failing that, an image of an individual of that taxon has sometimes been designated as a type.

Most have listed Thyreophora as an unranked taxon containing the traditional suborders Stegosauria and Ankylosauria, though Thyreophora is also sometimes classified as a suborder, with Ankylosauria and Stegosauria as infraorders.

The Crested Caracara is sometimes incorrectly referred to as " Guadalupe Caracara ", because the extinct birds were formerly considered a subspecies of the extant taxon.

The taxon Caenogastropoda was first established by Leslie Reginald Cox in 1960 as a superorder but now sometimes it is retained as a clade.

The taxon Anostominae is also used to denote the entire family in outdated treatments, where the name " Anostomidae " is applied to the entire Anostomoidea ( and sometimes even more distant relatives ).

Most have listed Thyreophora as an unranked taxon containing the traditional suborders Stegosauria and Ankylosauria, though Thyreophora is also sometimes classified as a suborder, with Ankylosauria and Stegosauria as infraorders.

Several of these are monophagous, meaning their caterpillars only feed on this genus, sometimes just on a single taxon of Eriogonum.

( sometimes this taxon is considered a subspecies of the European Green Woodpecker by some authors )

Osteons and their arrangement also vary according to taxon, so that genus and sometimes species can be differentiated using a bone fragment not otherwise identifiable, though there is considerable variability among the different bones of a skeleton, and features of some faunal osteons overlap with those of human osteons ; therefore, examination of osteons is not of primary use in the analyses of osteological remains.

This taxon is sometimes treated as a subspecies of Ophioglossum vulgatum, as O. vulgatum ssp.

These two defunct phyla were the Myxomycota ( i. e., plasmodial slime molds, now classified in the taxon Myxogastria ), and Acrasiomycota ( i. e. cellular slime molds, now divided into the taxa Acrasida and Dictyosteliida ).

** Animals that incorporated algae as photosynthetically active endosymbionts, i. e. primarily obtaining their nutrients from their partners in symbiosis, were accordingly responsible for the mysterious creatures of the Ediacara fauna that are not assigned to any modern animal taxon and lived during the Ediacaran Period, before the start of the Paleozoic.

Both characteristics can be considered apomorphies, i. e. evolutionarily derived features, and thus form the basis of a common taxon for all animals that possess them.

Together, the velvet worms, arthropods and water bears form a monophyletic taxon, the Panarthropoda, i. e., the three groups collectively cover all descendants of their last common ancestor.

The family Filoviridae is a virological taxon ( i. e. a man-made concept ) that was created in 1982 and emended in 1991, 1995, 2000, 2005, 2010 and 2011.

From the Permian numerous stem group representatives of mayflies are known, which are often lumped into a separate taxon Permoplectoptera ( e. g. including Protereismatidae and Misthodotidae ).

A Lazarus taxon is a taxon ( either one species or a group of species ) that suddenly reappears, either in the fossil record or in nature ( i. e. as if the fossil had " come to life again "), while a living fossil is a species that ( seemingly ) has not changed during its very long lifetime ( i. e. as if the fossil has always lived ).

So, a living species that was thought to be extinct ( e. g. the coelacanth, Latimeria chalumnae ) could be called a Lazarus taxon instead of a living fossil.

Although the name is always fixed to the type specimen, the circumscription ( i. e. range of specimens that may be included within the taxon ) is defined by the diagnosis and can be changed by formal emendation.

The order Mononegavirales is a virological taxon ( i. e. a man-made concept ) that was created in 1991 and emended in 1995, 1997, 2000, 2005, and 2011.

In zoological nomenclature, the type of a species ( or subspecies ) is a specimen ( or series of specimens ), the type of a genus ( or subgenus ) is a species, and the type of a suprageneric taxon ( e. g., family, etc.

Some of these elements ( e. g. musculature ) are not segmented in their sister taxon, the onychophora.

While in phylogeny where each taxon must consist of a single ancestral node and all its descendants, evolutionary taxonomy allows for groups to be excluded from their parent taxa ( e. g. dinosaurs are not considered to include birds, but to have given rise to them ), thus allowing for paraphyletic taxa.

Some workers, e. g., Pflug and Narbonne, suggest that a natural taxon Rangeomorpha may include all similar-looking fossils.

The genus Marburgvirus is a virological taxon ( i. e. a man-made concept ) included in the family Filoviridae, order Mononegavirales.

A name in three parts, i. e., an infraspecific name ( a name for a taxon below the rank of species ) needs a " connecting term " to indicate rank.

His decision was influenced by the fact that because Bambiraptor within a cladistic analysis was a member of a group, Paraves, that contained feathered true birds and that was the sister taxon of Oviraptorosauria, a group that also had feathered forms ( e. g. Caudipteryx ), Bambiraptor most likely had feathers too due to phylogenetic bracketing.

Some argue that the craniodental morphology of this taxon ( e. g., large postcanine dentition, thick enamel, robust mandibles, sagittal cresting, flaring zygomatic region ) are indicative of a diet of hard or tough foods such as ground tubers, nuts and seeds.

When an author considers that the taxonomic identity of a nominal species-group taxon cannot be determined from its existing name-bearing type ( i. e. its name is a nomen dubium ), and stability or universality are threatened thereby, the author may request the Commission to set aside under its plenary power 81 the existing name-bearing type and designate a neotype.

Archaeobacteria are prokaryotes, like eubacteria, however, and therefore are most facilely compared to eubacteria ( i. e., archaeobacteria represent a monophyletic taxon of bacteria-like things ).