Haikouichthys

Haikouichthys Temporal range: 535–520 Ma PreЄ Є O S D C P T J K Pg N
Restoration
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Superclass:	Agnatha
Order:	Myllokunmingiida
Family:	Myllokunmingiidae
Genus:	Haikouichthys Luo et al., 1999
Species
H. ercaicunensis Luo et al., 1999 (type)

Haikouichthys /ˌhaɪkuːˈɪkθɪs/ is an extinct genus of craniate (animals with and distinct heads) believed to have lived 525 million years ago, during the Cambrian explosion of multicellular life. Haikouichthys had a defined skull and other characteristics that have led paleontologists to label it a true craniate, and even to be popularly characterized as one of the earliest fishes. Cladistic analysis indicates that the animal is probably a basal chordate or a basal craniate; but it does not possess sufficient features to be included uncontroversially even in either stem group.

Haikouichthys is about 2.5 cm (0.98 in) long and is narrower than Myllokunmingia, another chordate that comes from the same beds. The holotype of Haikouichthys ercaicunensis was found in the Yuansshan member of the Qiongzhusi Formation in the 'Eoredlichia' Zone near Haikou at Ercaicun, Kunming City, Yunnan, China, hence its name "Haikou fish from Ercaicun". The fossil was recovered among the Chengjiang fauna, in one of a series of Lagerstätten sites where thousands of exquisitely preserved soft-bodied fossils have already been found. Following the discovery of the holotype, additional Lower Cambrian fossils of Haikouichthys ercaicunensis have been discovered.