Diania
| Diania | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Lower Cambrian | ||||||||||||
| 525 to 520 million years | ||||||||||||
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| Scientific name | ||||||||||||
| Diania | ||||||||||||
| Liu et al. , 2011 | ||||||||||||
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Diania is an extinct genus of multicellular animals (Metazoa) from the early Cambrian . Fossils of the only known species, D. cactiformis , were found in the Maotianshan schist in the Chinese Yunnan province and were first scientifically described in 2011. The type species owes its scientific nameon the one hand to the Chinese abbreviation Dian for the Yunnan province and on the other hand to its appearance, which resembles a cactus.
Fossil finds
The first description of Diania is based on three completely and over 30 other partially preserved fossils of D. cactiformis from the Maotianshan schist. These fossils, which belong to the Chengjiang Fauna Community , were discovered independently by Jianni Liu from the University of Northwest China in Xi'an , Qiang Ou from the Chinese University of Geosciences in Beijing and Michael Steiner from the Free University of Berlin .
features
Diania cactiformis was about six inches long and had an elongated body consisting of nine segments . It had a trunk at the front end of its body. A mouth could not be identified from the fossils, but there are indications of a body cavity or an intestine . Diania cactiformis wore ten pairs of presumably armored extremities on the not very robust body . These extremities were also segmented and articulated together. These sclerotized extremity segments, reinforced with projections, gave the animal its eponymous cactus-like appearance.
Systematics
Diania is assigned to the lobopods , an extinct group of sea-dwelling molting animals (Ecdysozoa), the possible ancestors of today's velvet worms (Onychophora). At the same time, the lobopods are considered to be a group of animals in which the evolutionary transition took place from the molting animals, surrounded by a comparatively soft cuticular body cover, to the arthropods armored with a hard exoskeleton . According to a cladistic analysis, Diania is the sister group of a clade of Schinderhannes and the Euarthropoda and thus closely related to the arthropods. Its hard-shelled extremities suggest that in the history of the development of the arthropods, the sclerotization of the extremities ( arthropodization ) occurred before the sclerotization of the body ( arthrodization ).
The systematic position illustrates the following simplified cladogram :
| Molting animals |
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literature
- Jianni Liu, Michael Steiner, Jason A. Dunlop, Helmut Keupp, Degan Shu, Qiang Ou, Jian Han, Zhifei Zhang & Xingliang Zhang: An armored Cambrian lobopodian from China with arthropod-like appendage . In: Nature . 470, No. 7335, August, pp. 526-530. doi : 10.1038 / nature09704 .