{{short description|Classification of organisms that do not fit in other classifications}} {{Use dmy dates|date=September 2022}} [[File:Protist collage 2.jpg|thumb|Collage of [[Protista]], one of the best-known wastebasket taxa. The vast majority of its members have little in common apart from being [[eukaryote]] lifeforms that are not [[Plant|plants]], [[Animal|animals]] or [[Fungus|fungi]].]] '''Wastebasket taxon''' (also called a '''waste-bin taxon''',<ref>{{cite journal|last=Friedman|first=M.|author2=Brazeau, M.D |title=Sequences, stratigraphy and scenarios: what can we say about the fossil record of the earliest tetrapods?|journal=[[Proceedings of the Royal Society]]|date=7 February 2011|volume=278|issue=1704|pages=432–439|doi=10.1098/rspb.2010.1321|pmid=20739322|pmc=3013411 |bibcode=2011PBioS.278..432F }}</ref> '''dustbin taxon'''<ref>{{Cite book | author1=Hallam, A.|author-link = Anthony Hallam|author2= Wignall, P. B. | title=Mass extinctions and their aftermath | year=1997 | publisher=Oxford University Press | location=Oxford [England] | isbn=978-0-19-854916-1 | page=107|url=https://books.google.com/books?id=06yrErJt_NsC&q=%22dustbin%20taxon%22&pg=PA107}}</ref> or '''catch-all taxon'''<ref name="monks2002">{{cite journal | author=Monks, N. | date=July 2002 | title= Cladistic analysis of a problematic ammonite group: the Hamitidae (Cretaceous, Albian-Turonian) and proposals for new cladistic terms | journal= Palaeontology | volume= 45 | pages=689–707 | doi=10.1111/1475-4983.00255 | issue=4| doi-access=free | bibcode=2002Palgy..45..689M }}</ref>) is a term used by some [[taxonomist]]s to refer to a [[taxon]] that has the purpose of classifying organisms that do not fit anywhere else. They are typically defined by either their designated members' often superficial similarity to each other, or their ''lack'' of one or more distinct [[Synapomorphy|character states]] or by their ''not'' belonging to one or more other taxa. Wastebasket taxa are by definition either [[paraphyletic]] or [[polyphyletic]], and are therefore not considered valid taxa under strict [[cladistic]] rules of taxonomy. The name of a wastebasket taxon may in some cases be retained as the designation of an [[evolutionary grade]], however.
==Examples==
There are many examples of paraphyletic groups, but true "wastebasket" taxa are those that are known not to, and perhaps not intended to, represent natural groups, but are nevertheless used as convenient groups of organisms. The kingdom [[Protist|Protista]] (see below) is perhaps the most famous example. Wastebasket taxa are often old (and perhaps not described with the systematic rigour and precision that is possible in the light of accumulated knowledge of diversity) and populous.<ref>{{cite journal | jstor=4096821 | title=Round up the Usual Suspects: Common Genera in the Fossil Record and the Nature of Wastebasket Taxa | last1=Plotnick | first1=Roy E. | last2=Wagner | first2=Peter J. | journal=Paleobiology | year=2006 | volume=32 | issue=1 | pages=126–146 | doi=10.1666/04056.1 | bibcode=2006Pbio...32..126P | s2cid=86606882 }}</ref>
* In 2022, the [[Pteromalidae]] (a [[Hymenoptera]] (wasp) family in the superfamily [[Chalcidoidea]] long considered [[Polyphyly|polyphylletic]]) was split into 24 families.<ref name=BurksEtAl>{{Cite Q|Q115923766|doi-access=free}}</ref> * The [[Flacourtiaceae]], a now-defunct family of [[flowering plant]]s<ref name="chase2002">{{cite journal |doi=10.2307/4110825 |first=Mark W. |last=Chase |author2=Sue Zmarzty |author3=M. Dolores Lledó |author4=Kenneth J. Wurdack |author5=Susan M. Swensen |author6= Michael F. Fay |year=2002 |title=When in doubt, put it in Flacourtiaceae: a molecular phylogenetic analysis based on plastid ''rbcL'' DNA sequences |jstor=4110825 |journal=[[Kew Bulletin]] |volume=57 |issue=1 |pages=141–181|bibcode=2002KewBu..57..141C }}</ref> – the [[Angiosperm Phylogeny Group]] has placed its [[Tribe (biology)|tribe]]s and genera in various other families, especially the [[Achariaceae]] and [[Salicaceae]]. * The obsolete kingdom [[Protista]] is composed of all [[eukaryote]]s that are not [[animal]]s, [[plant]]s or [[Fungus|fungi]], leaving to the protists all single-celled eukaryotes.<ref>{{cite journal |author=Whittaker RH |title=New concepts of kingdoms or organisms. Evolutionary relations are better represented by new classifications than by the traditional two kingdoms |journal=Science |volume=163 |issue=3863 |pages=150–60 |date=January 1969 |pmid=5762760 |doi=10.1126/science.163.3863.150|citeseerx=10.1.1.403.5430 |bibcode=1969Sci...163..150W }}</ref> * The [[Tricholomataceae]] is a fungal group, at one point composed of the white-, yellow-, or pink-spored genera in the [[Agaricales]] not already classified as belonging to the [[Amanitaceae]], [[Lepiotaceae]], [[Hygrophoraceae]], [[Pluteaceae]], or [[Entolomataceae]].<ref>{{cite journal |author=Young AM |year=2002 |title=Brief notes on the status of Family Hygrophoraceae Lotsy |journal=Australasian Mycologist |volume=21 |issue=3 |pages=114–6 }}</ref> * [[Carnosauria]] and [[Thecodontia]] are fossil groups, banded together back when the limited fossil record did not allow for a more detailed scheme. * [[Condylarthra]] is an artificial clade into which ungulate mammals not clearly within [[Odd-toed ungulate|Perissodactyla]] or [[Even-toed ungulate|Cetartiodactyla]] were traditionally shoved. Many of these groups, like [[Meridiungulata]] or ''[[Protungulatum]]'', may not represent [[Laurasiatheria|laurasitherian]] mammals, while others like [[Phenacodontidae|phenacodontid]]s have been clearly established as early odd-toed ungulates.<ref>{{cite web |url=https://blogs.scientificamerican.com/tetrapod-zoology/phenacodontidae-i-feel-like-i-know-you/ |website=Tetrapod Zoology |publisher=Scientific American |title=Phenacodontidae, I feel like I know you |first=Darren |last=Naish |date=8 August 2013 }}</ref><ref name="Cooper2014">{{cite journal |doi=10.1371/journal.pone.0109232 |pmid=25295875 |pmc=4189980 |title=Anthracobunids from the Middle Eocene of India and Pakistan Are Stem Perissodactyls |journal=PLOS ONE |volume=9 |issue=10 |article-number=e109232 |year=2014 |last1=Cooper |first1=Lisa Noelle |last2=Seiffert |first2=Erik R. |last3=Clementz |first3=Mark |last4=Madar |first4=Sandra I. |last5=Bajpai |first5=Sunil |last6=Hussain |first6=S. Taseer |last7=Thewissen |first7=J. G. M. |bibcode=2014PLoSO...9j9232C |doi-access=free }}</ref> * The order [[Insectivora]] has traditionally been used as a dumping ground for placental insectivorous mammals (and similar forms such as [[colugo]]s), usually aligned with [[Carnivora|carnivoran]]s, [[ungulate]]s and [[bat]]s. While the core components ([[Mole (animal)|mole]]s, [[shrew]]s, [[hedgehog]]s and their close relations) do in fact form a consistent clade, [[Eulipotyphla]], that is part of [[Laurasiatheria]] with the aforementioned clades, other mammals historically placed in the order have been found to belong to other branches of the placental tree: [[tree shrew]]s and colugos are [[euarchonta]]ns related to [[Primates]] and sometimes grouped in [[Sundatheria]], while [[tenrec]]s, [[golden mole]]s and [[elephant shrew]]s are all [[Afrotheria|afrothere]]s, probably forming the clade [[Afroinsectiphilia]]. Both of these clades have at times been accused of being wastebasket taxa themselves, grouping superficially similar animals in Euarchonta and Afrotheria, respectively, but they have been more strongly supported by genetic studies.{{fact|date=March 2019}} * [[Vermes]] is an obsolete taxon of worm-like animals. It was a catch-all term used by [[Carl Linnaeus]] and [[Jean-Baptiste Lamarck]] for non-arthropod invertebrate animals. *The genus ''[[Mamenchisaurus]]'' is sometimes considered a wastebasket taxon for large, long-necked [[dinosaur]]s.<ref name="moore2020">{{cite journal|last1=Moore|first1=A.J.|last2=Upchurch|first2=P.|last3=Barrett|first3=P.M.|last4=Clark|first4=J.M.|last5=Xing|first5=X.|year=2020|title=Osteology of ''Klamelisaurus gobiensis'' (Dinosauria, Eusauropoda) and the evolutionary history of Middle–Late Jurassic Chinese sauropods|journal=Journal of Systematic Palaeontology|volume=18|issue=16|pages=1299–1393|doi=10.1080/14772019.2020.1759706|bibcode=2020JSPal..18.1299M |s2cid=219749618}}</ref>
==Paleontology== [[Fossil]] groups that are poorly known due to fragmentary remains are sometimes grouped together on gross morphology or [[stratigraphy]], only later to be found to be wastebasket taxa, such as the crocodile-like [[Triassic]] group [[Rauisuchia]].<ref>{{cite journal |doi=10.1098/rsbl.2003.0066 |pmid=14667392 |pmc=1809943 |title=Arizonasaurus and its implications for archosaur divergence |journal=Proceedings of the Royal Society B: Biological Sciences |volume=270 |pages=S234-7 |year=2003 |last1=Nesbitt |first1=Sterling J. |issue=Suppl 2 |bibcode=2003PBioS.270.0066N }}</ref>
One of the roles of taxonomists is to identify wastebasket taxa and reclassify the content into more natural units. Sometimes, during taxonomic revisions, a wastebasket taxon 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 [[Taxonomy (biology)|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 abandoned altogether (for example, ''[[Simia]]'').{{fact|date=March 2019}}
==Related concepts== A related concept is that of [[form taxon]], "wastebasket" groupings that are united by gross morphology. This is often result of a common mode of life, often one that is [[generalist and specialist species|generalist]], leading to generally similar body shapes by [[convergent evolution]].{{fact|date=March 2019}}
The term wastebasket taxon is sometimes employed in a derogatory fashion to refer to an [[evolutionary grade]] taxon.{{fact|date=March 2019}}
== See also == * [[Lazarus taxon]] * [[Elvis taxon]] * ''[[Incertae sedis]]'' * [[Glossary of scientific naming]] * [[Not Otherwise Specified]]
== References == {{Reflist|2}}
[[Category:Obsolete taxa]] [[Category:Taxonomy (biology)]] [[Category:Paraphyletic groups]] [[Category:Polyphyletic groups]]