User:Snoteleks/Arthropoda
Phylogeny of stem-group arthropods[edit]
Modern interpretations of the basal extinct stem-group of Arthropoda separate it into the following groups, from most basal to most crownward[1][2]:
- The "Giant" or "Siberiid Lobopodians", such as Jianshanopodia, Siberion and Megadictyon, are the most basal grade in the total-group Arthropoda.
- The "Gilled Lobopodians", such as Kerygmachela, Pambdelurion and Opabinia, are the second most basal grade.
- The anomalocarids or Radiodonta come in third position, and are thought to be monophyletic.
- The Isoxyids have an established position as closer to the crown-group than anomalocarids[1] and, according to more recent stuidies, are inside the crown-group itself[3][4].
- An "upper stem-group" assemblage of three fossil groups of more uncertain position[1] but contained within Deuteropoda[2]: the Fuxianhuiida, the Megacheira and a group of bivalved arthropods known as Hymenocarina.
The Deuteropoda is a recently established clade uniting the crown-group (living) arthropods with these "upper stem-group" fossils of more uncertain positions[2]. The clade is defined by important changes to the structure of the head region such as the appearance of a differentiated first appendage pair (the deutocerebral pair)[2].
However, recent analyses show that these "upper stem-groups" might be inside the crown-group: Megacheira have been recovered as more closely related to Chelicerates[3][4], some bivalved forms such as Hymenocarina are consistently shown to be mandibulates[1], and similarly Fuxianhuiida might also be mandibulates[5].
The following cladogram shows the probable relationships between crown-group Arthropoda and stem-group Arthropoda as of 2022, including two new fossils found to be the most early branches of Deuteropoda[2][1][3][4] (living groups are marked in bold):
| Panarthropoda | ||
Note that the subphylum Artiopoda, containing the trilobites, is closer to mandibulates than to chelicerates in the cladogram above[3][4], but older analyses place them as the sister group of chelicerates[1] united under the clade Arachnomorpha.
Phylogeny of living arthropods[edit]
The following cladogram shows the internal relationships between all the living classes of arthropods as of 2022[6][7]:
| Arthropoda |
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- ^ a b c d e f Gregory D. Edgecombe (2020), "Arthropod Origins: Integrating Paleontological and Molecular Evidence", Annu. Rev. Ecol. Evol. Syst., 51: 1–25, doi:10.1146/annurev-ecolsys-011720-124437
- ^ a b c d e Ortega-Hernández, Javier (2016), "Making sense of 'lower' and 'upper' stem-group Euarthropoda, with comments on the strict use of the name Arthropoda von Siebold, 1848", Biol. Rev., 91 (1): 255–273, doi:10.1111/brv.12168, PMID 25528950, S2CID 7751936
- ^ a b c d Zeng, Han; Zhao, Fangchen; Niu, Kecheng; Zhu, Maoyan; Huang, Diying (November 2020), "An early Cambrian euarthropod with radiodont-like raptorial appendages", Nature, 588: 101–105, doi:10.1038/s41586-020-2883-7
- ^ a b c d O’Flynn, Robert; Williams, Mark; Yu, Mengxiao; Harvey, Thomas; Liu, Yu (2022), "A new euarthropod with large frontal appendages from the early Cambrian Chengjiang biota", Palaeontologia Electronica, 25 (1): a6, doi:10.26879/1167
- ^ Aria, Cédric; Caron, Jean-Bernard (April 2017), "Burgess Shale fossils illustrate the origin of the mandibulate body plan", Nature, 545: 89–92, doi:10.1038/nature22080
- ^ Lozano-Fernandez, Jesus; Giacomelli, Mattia; F. Fleming, James; Chen, Albert; Vinther, Jakob; Thomsen, Philip Francis; Glenner, Henrik; Palero, Ferran; A. Legg, David; M. Iliffe, Thomas; Pisani, Davide; Olesen, Jørgen (2019), "Pancrustacean Evolution Illuminated by Taxon-Rich GenomicScale Data Sets with an Expanded Remipede Sampling", Genome Biol. Evol., 11 (8): 2055–2070, doi:10.1093/gbe/evz097
- ^ Giribet, Gonzalo; Edgecombe, Gregory (June 2019), "The Phylogeny and Evolutionary History of Arthropods", Current Biology, 29 (12): R592–R602, doi:10.1016/j.cub.2019.04.057