Megadictyon

{{Taxobox

| fossil_range = {{Fossil range|Cambrian Stage 3}}

| image = 20191118_Megadictyon_cf._haikouensis.png

| image_caption = Reconstruction of Megadictyon cf. haikouensis

| regnum = Animalia

| phylum = Lobopodia

| classis = †Xenusia

| ordo = †Siberiida

| familia = †Siberiidae

| genus = †Megadictyon

| genus_authority = Luo & Hu, 1999

| species = †M. haikouensis

| binomial = †Megadictyon haikouensis

| binomial_authority = Luo & Hu, 1999

}}

Megadictyon is a genus of Cambrian lobopodian with similarities to Jianshanopodia and Siberion. The name of the genus is occasionally mis-spelt as Magadictyon.{{Cite journal|url = https://onlinelibrary.wiley.com/doi/10.1111/j.1463-6395.2007.00307.x|doi = 10.1111/j.1463-6395.2007.00307.x|title = Corrigendum|journal = Acta Zoologica|year = 2007|volume = 89|issue = 2|page = 183|url-access = subscription}}

Description

Megadictyon is a large lobopodian, with a body length (excluding appendages) possibly up to 20 centimeters in total.{{Cite journal |author=Liu, J.-N. |author2=Shu, D.-G. |author3=Han, J. |author4=Zhang, Z.-F. |author5=Zhang, X.-L. |year= 2007|title=Morpho-anatomy of the lobopod Magadictyon cf. haikouensis from the Early Cambrian Chengjiang Lagerstätte, South China |journal=Acta Zoologica |volume=88 |issue=4 |pages=279–288 |doi=10.1111/j.1463-6395.2007.00281.x}} The head has a pair of robust frontal appendages{{Cite journal |author=Liu, J.-N. |author2=Shu, D.-G. |author3=Han, J. |author4=Zhang, Z.-F. |author5=Zhang, X. |year=2008 |title= Origin, diversification, and relationships of Cambrian lobopods |journal= Gondwana Research |volume=14 |issue=1–2 |pages=277–283 |bibcode=2008GondR..14..277L |doi=10.1016/j.gr.2007.10.001 }} associated with rows of spines and terminal claws. Located on the underside of the head is a radiodont-like mouthpart formed by multiple layers of plates and tooth-like structures. 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. It also has pairs of digestive glands similar to those of basal arthropods.{{Cite journal |doi= 10.1038/ncomms4641|pmid = 24785191 |year= 2014 |title= Sophisticated digestive systems in early arthropods |journal= Nature Communications|volume = 5 |page= 3641 |last1= Vannier |first1 = Jean |last2= Liu |first2= Jianni |last3= Lerosey-Aubril |first3= Rudy |last4=Vinther|first4= Jakob |last5= Daley |first5= Allison C |bibcode= 2014NatCo...5.3641V|doi-access= free }}

Phylogeny

Phylogenetic position of Megadictyon according to Pates et al. (2022).{{Cite journal| doi = 10.1098/rspb.2021.2093| volume = 289| issue = 1968| last1 = Pates| first1 = Stephen| last2 = Wolfe| first2 = Joanna M.| last3 = Lerosey-Aubril| first3 = Rudy| last4 = Daley| first4 = Allison C.| last5 = Ortega-Hernández| first5 = Javier| title = New opabiniid diversifies the weirdest wonders of the euarthropod stem group| journal = Proceedings of the Royal Society B: Biological Sciences| date = 2022-02-09| pmid = 35135344| pmc = 8826304| doi-access = free}}

{{clade|style=font-size:95%;line-height:95%

|1={{clade

|1=Aysheaia

|2=Onychodictyon

|3=Tardigrada

|4=Onychophora

|5={{clade

|1={{clade

|1=Megadictyon

|2=Jianshanopodia

}}

|2={{clade