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Myllokunmingia
From Wikipedia, the free encyclopedia
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Extinct (fossil)
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| Myllokunmingia fengjiaoa |
Myllokunmingia is a primitive, probably agnathan (jawless) fish from the Lower Cambrian Maotianshan shales of China, thought to be a vertebrate (see external links). It somewhat resembles hagfish, which live today. It is described as 28 mm long and 6 mm high.
It is the oldest vertebrate known, found in rocks of the Cambrian period (530 Ma old). 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 can not 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.
A similar creature from these shales is known as Haikouichthys. Suspected chordates (more primitive hemichordates) are also known from these deposits.
There is one species - Myllokunmingia fengjiaoa (Shu, Zhang & Han).