Wastebasket taxon
2094855
211857617
2008-05-12T12:35:56Z
Smith609
846901
Simplify and correct invertebrates discussion
'''Wastebasket taxon''' (also called a '''wastebin taxon''' or '''dustbin taxon''') is a term used in [[Alpha taxonomy|taxonomic]] circles to refer to a [[taxon]] that has the sole purpose of classifying organisms that do not fit anywhere else. They are typically defined by their ''lack'' of one or more distinct [[character states]] or by their ''not'' belonging one or more other taxa. Wastebasket taxa are by definition either [[paraphyletic]] or [[polyphyletic]], and are therefore not considered to be valid taxa under modern rules of taxonomy.
The familiar category of [[invertebrates]] is an "everything-else" category, comprising all animals without backbones. Other examples of wastebasket taxa include the [[Protista]], [[Carnosauria]], [[Thecodontia]], and [[Tricholomataceae]]. Sometimes, during taxonomic revisions, the wastebasket taxa can be salvaged after doing thorough research on its members, and then imposing tighter restrictions on what continues to be included. Such techniques "saved" Carnosauria and ''[[Megalosaurus]]''. Other times, the [[taxonomic]] name contains too much unrelated "baggage" to be successfully salvaged. As such, it is usually dumped in favour of a new, more restrictive name (for example, [[Rhynchocephalia]] or Thecodontia), or abandoned altogether (for example, ''[[Simia]]'').
A related concept is that of '''form taxon'''. Form taxa are "wastebasket" groupings that are united by a common mode of life, often one that is [[generalist]], in consequence acquiring generally similar body shapes by [[convergent evolution]]. [[Ediacaran biota]] — whether they are the precursors of the [[Cambrian explosion]] of the fossil record, or are unrelated to any modern phylum — can currently only be grouped in "form taxa". Other examples include the [[seabirds]] and the "[[Graculavidae]]". The latter were initially described as the earliest [[family (biology)|family]] of [[Neornithes]] but are nowadays recognized to unite a number of unrelated early neornithine lineages, several of which probably later gave rise to the "seabird" form taxon of today.
==See also==
* [[Lazarus taxon]]
* [[Elvis taxon]]
[[Category:Scientific classification]]
[[Category:Taxonomy]]
[[hu:Szemétkosár-taxon]]
[[sv:Papperskorgstaxon]]