Megadictyon

Megadictyon Temporal range: Cambrian Stage 3 PreꞒ Ꞓ O S D C P T J K Pg N
Reconstruction of Megadictyon cf. haikouensis
Scientific classification
Kingdom:	Animalia
Phylum:	Lobopodia
Class:	†Xenusia
Order:	†Siberiida
Family:	†Siberiidae
Genus:	†Megadictyon Luo & Hu, 1999
Species:	†M. haikouensis Luo & Hu, 1999

Megadictyon is a genus of Cambrian lobopodian with similarities to Jianshanopodia and Siberion. Occasionally mis-spelt 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

Phylogenetic position of Megadictyon according to Pates et al. (2022).[5]

	Aysheaia Onychodictyon Tardigrada Onychophora Megadictyon Jianshanopodia Hadranax Kerygmachela Pambdelurion Utaurora Opabinia Aegirocassis Peytoia Schinderhannes bartelsi Cambroraster Hurdia Amplectobelua Lyrarapax Anomalocaris Houcaris Deuteropoda

References

1. "Corrigendum". Acta Zoologica. 89 (2): 183. 2007. doi:10.1111/j.1463-6395.2007.00307.x.
2. 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. Pates, Stephen; Wolfe, Joanna M.; Lerosey-Aubril, Rudy; Daley, Allison C.; Ortega-Hernández, Javier (2022-02-09). "New opabiniid diversifies the weirdest wonders of the euarthropod stem group". Proceedings of the Royal Society B: Biological Sciences. 289 (1968). doi:10.1098/rspb.2021.2093. PMC 8826304. PMID 35135344.