| Myllokunmingia | |
|---|---|
 | |
| Fossil ofMyllokunmingia fengjiaoa | |
 | |
| An artist's conception ofMyllokunmingia fengjiaoa | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Order: | †Myllokunmingiida |
| Family: | †Myllokunmingiidae |
| Genus: | †Myllokunmingia Shu, Zhang & Han, 1999 |
| Species: | †M. fengjiaoa |
| Binomial name | |
| †Myllokunmingia fengjiaoa Shu, Zhang & Han, 1999 | |
Myllokunmingia is a genus ofbasalchordate from the LowerCambrianMaotianshan shales ofChina 518 mya and is thought to be avertebrate,[2] although this is not conclusively proven.[3] Thetype speciesM. fengjiaoa is 28 mm long and 6 mm high. It is among the oldest possiblecraniates, found in the lower CambrianChengjiang (518 million years ago). It appears to have askull and skeletal structures made ofcartilage. There is no sign ofbiomineralization of the skeletal elements. Theholotype was found in the Yuanshan member of the Qiongzhusi Formation in the Eoredlichia Zone near Haikou at Ercaicun,Kunming City,Yunnan, China. Some researchers have considered the other primitive chordateHaikouichthys to be synonymous with this taxon,[4] but subsequent studies led by the British paleontologistSimon Conway Morris identified both genera to be distinct, separate taxa on the basis of different gill arrangement,[5] the absence of branchial rays inMyllokunmingia and the myomeres having a more acute shape inHaikouichthys.[6]
The animal has a distinct head and trunk with a forward sail-like (1.5 mm)dorsal fin and aventral finfold (probably paired) further back. The maximum height ofM. fengjiaoa is at 6mm. The maximum height point is located around 11mm from the anterior. The head has five or sixgill pouches withhemibranchs. In the trunk there are 25 segments (myomeres) with rearward-facing chevrons. There is anotochord, apharynx and adigestive tract that may run all the way to the rear tip of the animal. The mouth cannot be clearly identified. There may be apericardial cavity. There are no fin radials on M. fengjiaoa. There is only one specimen, which has the tip of the tail buried insediment.[2]
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