Myllokunmingia.html |
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| Myllokunmingia Fossil range: Early Cambrian |
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| Scientific classification | ||||||||
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| Binomial name | ||||||||
| Myllokunmingia fengjiaoa |
Myllokunmingia is a primitive, probably agnathid, jawless fish from the Lower Cambrian Maotianshan shales of China, thought to be a vertebrate,1 although this is not conclusively proven.2 It somewhat resembles modern hagfish, and is 28 mm long and 6 mm high.
It is the oldest vertebrate known, found in the lower Cambrian Chengjiang (). It appears to have a skull and skeletal structures made of cartilage (like lampreys, which are also vertebrates). There is no sign of mineralization of the skeletal elements (biomineralization).
The holotype was found in the Yuanshan member of the Qiongzhusi Formation in the Eoredlichia Zone near Haikou at Ercaicun, Kunming City, Yunnan, China. The animal has a distinct head and trunk with a forward sail-like (1.5 mm) dorsal fin and a ventral fin fold (probably paired) further back. The head has five or six gill pouches with hemibranchs. There are 25 segments (myomeres) with rearward chevrons in the trunk. There is a notochord, a pharynx and digestive tract that may run all the way to the rear tip of the animal. The mouth cannot be clearly identified. There may be a pericardic cavity. There are no fin radials. There is only one specimen, which has the tip of the tail buried in sediment. 1
There is one species - Myllokunmingia fengjiaoa (Shu, Zhang & Han).
A similar creature from these shales is known as Haikouichthys. Suspected hemichordates are also known from these deposits.
References
- ^ a b Shu, D-G. (1999). Nature 402: 42. doi:.
- ^ Donoghue, P.C.J.; Purnell, M.A. (2005), "Genome duplication, extinction and vertebrate evolution", Trends in Ecology & Evolution 20 (6): 312–319, http://palaeo.gly.bris.ac.uk/Publs/donoghue/Donoghue_and_Purnell_2005.pdf
