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Haikouichthys ercaicunensis was a primitive fish-like animal from the Middle Cambrian Maotianshan shales of China.
Cladistic analysis indicates that the animal is probably a primitive agnathid fish most closely related to the Lampreys. It is about 2.5cm long and is narrower than the Myllokunmingia, another primitive fish that comes from the same beds. The holotype was found in the Yuansshan 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. The head has at least six and perhaps nine probable gills. There are a number of segments (myomeres) with rear directed Vs in the trunk. There is probably a notochord although only a short segment is preserved in the single known specimen. The tail end of the animal is apparently missing. There is a prominent dorsal fin with fin radials. The fin radials seem to angle "forward" toward the end thought on the basis of internal structures to be the head. This happens with a few modern fish but is an uncommon arrangement. There is a ventral fin fold. There are 13 circular structures along the bottom that may be gonads, slime organs, or something else entirely. There is no sign of mineralization of the skeletal elements.
A similar creature from these shales is known as Myllokunmingia.
There is one species Haikouichthys ercaicunensis Luo, Hu & Shu.
In popular culture
Haikouichthys appeared in Walking with Monsters. A school of Haikouichthys was shown attacking an injured Anomalocaris. This type of behavior is speculative.
Relationship to other Vertebrates
The creators of Walking with Monsters suggested that Haikouichthys was the ancestor of all vertebrates, including us humans. 5 million years earlier, a primitive chordate already existed, it was Pikaia. Pikaia had a primitive backbone as well. Some scientists believe that our earliest known ancestor was Pikaia, while others believe it was the calcichordates (with an example being Cothurnocystis). Haikouichthys was actually distantly related to todays lampreys (being grouped in Agnatha), and thus, could be a possible ancestor of Cephalaspis, as speculated in Walking with Monsters.
External links
- See the following web sites for more information and pictures:
- http://www.sciencenews.org/sn_arc99/11_6_99/fob1.htm
- http://news.bbc.co.uk/1/hi/sci/tech/504776.stm
See also
"Haikouichthys"