World Library  
Flag as Inappropriate
Email this Article

Cephalochordate

Article Id: WHEBN0000938003
Reproduction Date:

Title: Cephalochordate  
Author: World Heritage Encyclopedia
Language: English
Subject: Chordate, Cephalochordata, Endostyle, List of chordate orders, Cambrian first appearances
Collection: Cambrian First Appearances, Cephalochordata, Hemichordates
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Cephalochordate

Cephalochordata
Temporal range: Middle Cambrian–Recent
Є
O
S
D
C
P
T
J
K
Pg
N
A Branchiostoma lanceolatum lancelet
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Cephalochordata
Haeckel, 1866[1]
Groups
Synonyms
  • Pharyngobranchii (or Cirrhostomi) Owen, 1846
  • Amphioxidei Bleeker, 1859
  • Acrania Haeckel, 1866

Cephalochordata (from Greek: κεφαλή kephalé, "head" and χορδή khordé, "chord") is a chordate subphylum defined by the presence of a notochord that persists throughout life. It is represented in the modern oceans by the Amphioxiformes (lancelets, also known as amphioxus). Along with its sister phylum Urochordata, Cephalochordata can be classified as belonging to the taxon Protochordata.[2]

The characteristics of Cephalochordata are that they are marine animals, segmented, and that they possess elongated bodies with a notochord that extends the length of the body and cirri surrounding the mouth for obtaining food. In cephalochordata the notochord extends from head to tail and it persists throughout their life.[3] The members of this subphylum are very small and have no hard parts, making their fossils difficult to find. Fossilized species have been found in very old rocks predating vertebrates. There is famous fossil shale from the Middle Cambrian Burgess Shale of British Columbia, which has yielded Pikaia fossils. Recently a different cephalochordate fossil (Yunnanozoon) has been found in south China. It dates to the early Cambrian period and is the earliest known fossil of the cephalochordate lineage.[4] They have numerous gill slits, and have separate sexes.

Phylogeny

This phylogeny is based on a combination of studies of extinct [5] and extant [6] species.



Pikaia gracilens Walcott 1911

Leptocardii

Cathaymyrus Shu, Conway Morris & Zhang 1996

Acrania

Paleobranchiostoma hamatotergum Oelofsen & Loock 1981

Branchiostomiformes

Asymmetron Peters 1876



Epigonichthys Andrews 1893


Branchiostoma Costa 1834






References

  1. ^ Nielsen, C. (2012). "The authorship of higher chordate taxa". Zoologica Scripta 41 (4): 435–436.  
  2. ^ Hickman. Animal Diversity. Michael S. Hackett. p. 313. 
  3. ^ K.M. Van De Graaff and J.L. Crawley, A Photographic Atlas for the Zoology Laboratory
  4. ^ Chen, J.-Y., Dzik, J., Edgecombe, G.D., Ramsköld, L., and Zhou, G.-Q. 1995. "A possible Early Cambrian chordate" Nature 377: 720-722.
  5. ^ Haaramo, Mikko. Cephalochordata – lancelets. Retrieved 2013-10-22. 
  6. ^ Kon, T.; et al. (2006). "Hidden ancient diversification in the circumtropical lancelet Asymmetron lucayanum complex". Marine Biology 149 (4): 875–883.  


This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.