Haikouichthys

Haikouichthys
Temporal range: Cambrian Stage 3, 518 Ma[1]
Restoration
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Order: Myllokunmingiida
Family: Myllokunmingiidae
Genus: Haikouichthys
Luo et al., 1999
Species:
H. ercaicunensis
Binomial name
Haikouichthys ercaicunensis
Luo et al., 1999

Haikouichthys /ˌhkuˈɪkθɪs/ is an extinct genus of craniate (animals with notochords and distinct heads) that lived 518 million years ago, during the Cambrian explosion of multicellular life. The type species, Haikouichthys ercaicunensis, was first described in 1999.[2] 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. More than 500 specimens were referred to this taxon and phylogenetic analyses indicates that the animal is probably a basal stem-craniate.[3] Some researchers have considered Haikouichthys to be synonymous with the other primitive chordate Myllokunmingia,[4] but subsequent studies led by the British paleontologist Simon Conway Morris identified both genera to be distinct, separate taxa on the basis of different gill arrangement,[5] the absence of branchial rays in Myllokunmingia and the myomeres having a more acute shape in Haikouichthys.[6]

  1. ^ Yang, C.; Li, X.-H.; Zhu, M.; Condon, D. J.; Chen, J. (2018). "Geochronological constraint on the Cambrian Chengjiang biota, South China" (PDF). Journal of the Geological Society. 175 (4): 659–666. Bibcode:2018JGSoc.175..659Y. doi:10.1144/jgs2017-103. ISSN 0016-7649. S2CID 135091168.
  2. ^ Shu, D-G.; Luo, H-L.; Conway Morris, S.; Zhang, X-L.; Hu, S-X.; Chen, L.; Han, J.; Zhu, M.; Li, Y.; Chen, L-Z. (1999). "Lower Cambrian vertebrates from south China". Nature. 402 (6757): 42. Bibcode:1999Natur.402...42S. doi:10.1038/46965. S2CID 4402854.
  3. ^ Shu, D. G.; Conway Morris, S.; Han, J.; Zhang, Z. F.; Yasui, K.; Janvier, P.; Chen, L.; Zhang, X. L.; Liu, J. N.; Li, Y.; Liu, H. -Q. (2003). "Head and backbone of the Early Cambrian vertebrate Haikouichthys". Nature. 421 (6922): 526–529. Bibcode:2003Natur.421..526S. doi:10.1038/nature01264. PMID 12556891. S2CID 4401274.
  4. ^ Hou, X.-G.; Aldridge, R. J.; Siveter, D. J.; Feng, X.-H. (2002). "New evidence on the anatomy and phylogeny of the earliest vertebrates". Proc Biol Sci. 269 (1503): 1865–1869. doi:10.1098/rspb.2002.2104. PMC 1691108. PMID 12350247.
  5. ^ Conway Morris, S. (29 June 2006). "Darwin's dilemma: the realities of the Cambrian 'explosion'". Philosophical Transactions of the Royal Society B: Biological Sciences. 361 (1470): 1069–1083. doi:10.1098/rstb.2006.1846. PMC 1578734. PMID 16754615.
  6. ^ Conway Morris, Simon; Caron, Jean-Bernard (2012). "Pikaia gracilens Walcott, a stem-group chordate from the Middle Cambrian of British Columbia". Biological Reviews. 87 (2): 480–512. doi:10.1111/j.1469-185X.2012.00220.x. PMID 22385518. S2CID 27671780.