Microdictyon is an extinct "armored worm" coated with net-like scleritic scales, known from the Early CambrianMaotianshan shale of YunnanChina. Microdictyon is sometimes included in a somewhat ill-defined Phylum - Lobopodia - that includes several other odd worm-like and segmented free-swimming animals that do not appear to be arthropods or worms. The phylum includes Microdictyon, Onychodictyon, Cardiodictyon, Luolishania, and Paucipodia. The isolated sclerites of Microdictyon are known from other Lower Cambrian deposits. Microdictyon sclerites appear to have moulted; one sclerite seems to have been preserved during ecdysis. Microdictyon sinicum is typical. The wormlike animal has ten pairs of sclerites on the sides, matched to a pair of tentacle-like feet below. The head and posterior are tubular and featureless.
Species composition
Type species. Microdictyon effusum Bengtson, Matthews et Missarzhevsky, 1981; Lower Cambrian, Atdabanian Stage, Kazakhstan; Atdabanian and Botomian Stages, Russia and England; Lower Cambrian, Sweden.
M. anus Tong, 1989, Lower Cambrian, upper Meishucunian Stage, China.
M. chinense Hao et Shu, 1987, Lower Cambrian, Qiongzhusi Stage, China ; Atdabanian through Botomian stages, Siberian Platform.
M. cuneum Wotte et Sundberg, 2017, Lower Cambrian, Montezuman Stage, the United States.
M. depressum Bengtson, 1990, Lower Cambrian, Atdabanian through Botomian Stages, South Australia.
M. fuchengenseLi et Zhu, 2001, Lower Cambrian, upper Meishucunian Stage, China.
M. jinshaense Zhang et Aldridge, 2007, Lower Cambrian, Qiongzhusi Stage, China.
M. montezumaensis Wotte et Sundberg, 2017, Lower Cambrian, Montezuman Stage, the United States.
M. rhomboidale Bengtson, Matthews et Missarzhevsky, 1986, Lower Cambrian, upper parts of the Atdabanian Stage, Kazakhstan; Atdabanian Stage, Canada, the United States.
M. robisoni Bengtson, Matthews et Missarzhevsky, 1986, Middle Cambrian, Amgan Stage, the United States;
M. sinicum Chen, Hou et Lu, 1989, Lower Cambrian, upper Meishucunian Stage Stage, China (Yunnan.
M. sphaeroides Hinz, 1987, Lower Cambrian, Atdabanian Stage, Great Britain.
M. tenuiporatum Bengtson, Matthews et Missarzhevsky, 1986, Lower Cambrian, Atdabanian Stage, Siberian Platform.
A picture can be found at https://web.archive.org/web/20030730043530/http://paws.wcu.edu/dperlmutr/earlyfauna.html. ---- The name Microdictyon is also used for a genus of green algae.
