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Megadictyon is a genus of Cambrian lobopodian with similarities to Jianshanopodia and Siberion. The name of the genus is occasionally mis-spelt as Magadictyon.[1]

Description

Megadictyon is a large lobopodian, with a body length (excluding appendages) possibly up to 20 centimeters in total.[2] The head has a pair of robust frontal appendages[3] associated with rows of spines and terminal claws.[2] Located on the underside of the head is a radiodont-like mouthpart formed by multiple layers of plates and tooth-like structures.[2] The trunk is wide and annulated, with a pair of well-developed lobopodous limbs on each body segment. Only 8 segment/limb pairs are countable in the incomplete fossil materials which are lacking the posterior region, so it may have had more (possibly up to 11 to 13) in nature.[2] It also has pairs of digestive glands similar to those of basal arthropods.[2][4]

Phylogeny

Phylogeny of Panarthropoda and lobopodians after Knetcht et al. 2025:[5]

†Diania

Cladogram after McCall 2023:[6]

Total group Euarthropoda

References

  1. ^ “Corrigendum”. Acta Zoologica. 89 (2): 183. 2007. doi:10.1111/j.1463-6395.2007.00307.x.
  2. ^ a b c d e Liu, J.-N.; Shu, D.-G.; Han, J.; Zhang, Z.-F.; Zhang, X.-L. (2007). “Morpho-anatomy of the lobopod Magadictyon cf. haikouensis from the Early Cambrian Chengjiang Lagerstätte, South China”. Acta Zoologica. 88 (4): 279–288. doi:10.1111/j.1463-6395.2007.00281.x.
  3. ^ Liu, J.-N.; Shu, D.-G.; Han, J.; Zhang, Z.-F.; Zhang, X. (2008). “Origin, diversification, and relationships of Cambrian lobopods”. Gondwana Research. 14 (1–2): 277–283. Bibcode:2008GondR..14..277L. doi:10.1016/j.gr.2007.10.001.
  4. ^ Vannier, Jean; Liu, Jianni; Lerosey-Aubril, Rudy; Vinther, Jakob; Daley, Allison C (2014). “Sophisticated digestive systems in early arthropods”. Nature Communications. 5: 3641. Bibcode:2014NatCo…5.3641V. doi:10.1038/ncomms4641. PMID 24785191.
  5. ^ Knecht, Richard J.; McCall, Christian R. A.; Tsai, Cheng-Chia; Rabideau Childers, Richard A.; Yu, Nanfang (23 July 2025). “Palaeocampa anthrax, an armored freshwater lobopodian with chemical defenses from the Carboniferous”. Communications Biology. 8 (1) 1080. doi:10.1038/s42003-025-08483-0. PMC 12287526. PMID 40702124.
  6. ^ McCall, C. R. A. (2023). “A large pelagic lobopodian from the Cambrian Pioche Shale of Nevada”. Journal of Paleontology. 97 (5): 1–16. Bibcode:2023JPal…97.1009M. doi:10.1017/jpa.2023.63.