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John Meszaros:

Anomalocaris group. going clockwise from the lower left, the animals are: Anomalocaris canadensis, Amplectobelua symbrachiata, Hurdia victoria, Opabinia regalis, Kerygmachela kierkegaardi, Schinderhannes bartelsi, Pambdelurion whittingtoni and Laggania cambria.

Lobopods. Clockwise from top: Microdictyon sinicum, Hallucigenia sparsa, Onychodictyon ferox and Aysheaia pedunculata. Note, by the way, that what appear to be “eyes” on Microdictyon, Hallucigenia and Onychodictyon are actually sclerotized armor plates.

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Microdictyon.
Found in the shale deposits in China, this was an odd worm-like organism from the Early Cambrian epoch. It possessed pairs of sclerotic structures along its sides, which may have been early eye-like structures. These were matched by pairs of tentacles which appear to have been used for locomotion.

The armored worm, Microdictyon (1989)

Phylum : Lobopodia
Class : Xenusia
Order : Scleronychophora
Family : Eoconchariidae
Genus : Microdictyon
Species : M. sinicum

  • Early/middle Cambrian (540 - 507 Ma)
  • 25 mm long (size)
  • China (map)

Microdictyon is an extinct “armored worm” coated with dot-like scleritic scales, known from the Early Cambrian Maotianshan shale of Yunnan China. 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, Paucipodia, as well as the Anomalocarids. 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 (Chen, Hou and Lu, 1989) is typical. The wormlike animal has ten pairs of sclerites (suggestions that these may be eyes or eye-like structures have no weight) on the sides, matched to a pair of tentacle-like feet below. The head and posterior are tubular and featureless.

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