Artiopoda Temporal range:Early Cambrian - Late Permian PreꞒ Ꞓ O S D C P T J K Pg N
Misszhouia, anektaspid
Cheloniellon, acheloniellid
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
(unranked):	†Artiopoda Hou and Bergstrom, 1997
Subgroupings
†Siriocaris? †Squamacula †Thulaspis †Urokodia[1] †Notchia?[2] Protosutura †Acanthomeridion †Zhiwenia †Australimicola †Campanamuta †Falcatamacaris †Molaria †Retifacies †Pygmaclypeatus †Bailongia †Strabopida? Trilobitomorpha †Retifacies? †Pygmaclypeatus? †Campanamuta? †Kwanyinaspis †Arthroaspis †Tonglaiia[3] †Nektaspida †Trilobita †Agnostida?(Traditionally included within Trilobita) †Conciliterga †Xandarellida (=Petalopleura) Vicissicaudata †Sidneyia †Emeraldella †Etainia †Kodymirus †Eozetetes †Tardisia †Carimersa †Cheloniellida †Aglaspidida

Artiopoda is aclade of extinctarthropods that includestrilobites and their close relatives. It was erected by Hou and Bergström in 1997^[4] to encompass a wide diversity of arthropods that would traditionally have been assigned to the Trilobitomorpha. Trilobites, in part due to abundance of findings owing to their mineralized exoskeletons, are by far the best recorded, diverse, and long lived members of the clade. Other members, which lack mineralised exoskeletons, are known mostly fromCambrian deposits.^[5]

According to Stein and Selden (2012) artiopods are recognised by the possession offiliformantennulae,limbs with bilobateexopods (upper branches), with the proximal (closest to base of the limb) lobe being elongate and bearing a lamella, while the distal (further from the limb base) lobe is paddle-shaped andsetiforous (bearing hair-or bristle like structures). The limbendopod (inner, leg-like branch) has sevenpodomeres/segments, with first four podomeres bearing inward facing (endite) structures, while podomeres five and six are stenopodous (cylindrical and stout). Commonplesiomorphies also include the antennules and at least three sets of post-antennular limbs being incorporated into the head shield, the postantennular limbs having no or little differentiation into distinct morphologies, and broad paratergal folds which contribute to thedorsoventrally (along the up-down axis) flattened look of artiopods.^[6] The limbs of artiopods have also been suggested to bearexites, which were described as similar those of themegacheiranLeanchoilia and probably nothomologous to those present in crustaceans.^[7]

The Artiopoda have been considered by many studies to consist of two major clades; one reusing Trilobitomorpha to encompass trilobites,nektaspids, concilitergans and xandarellids, and the other calledVicissicaudata encompassingaglaspidids,xenopods andcheloniellids.^[8] There are some taxa, such asSquamacula and the members of "Protosutura", which often are placed near the base of Artiopoda, outside the Vicissicaudata+Trilobitomorpha clade. These relationships are not always recovered.^[9]

The relationship of Artiopoda with the two major clades of modern arthropods, theChelicerata and theMandibulata, are unresolved, with some phylogenies recovering Artiopoda as more closely to chelicerates, forming the cladeArachnomorpha, while others recover Artiopoda as more closely related to mandibulates, forming the cladeAntennulata.^[10] Some studies place them as stem-group euarthropods, with mandibulates and chelicerates more closely related to each other than either is to Artiopoda.^[9] Some studies have recovered a close relationship withMarrellomorpha, with the proposed clade including Artiopoda and Marrellomorpha dubbedLamellipedia, though this relationship is not found in other analyses.^[11][12] The enigmatic artiopodan-like arthropodKiisortoqia, which bears large "frontal appendages" has been suggested to be closely related to Artiopoda in some analyses.^[9]

After Jiao et al. 2021.^[13]

Implied weights parsimony phylogeny after Berks et al. 2023.^[14]

• Artiopoda
• Arthropod taxa
• Taxa described in 1997
• Cambrian first appearances
• Lopingian extinctions

• Articles with short description
• Short description is different from Wikidata
• Articles with 'species' microformats
• Pages using gallery without a media namespace prefix