| fossil_range = {{fossil range|530|0|ref=<ref name=Xian-guang2002>{{Cite journal | الأخير = Xian-guang | الأول = H. | المؤلفينمؤلفين المشاركينمشاركين =Richard J. Aldridge2, David J. Siveter2,Derek J. Siveter3,4 and Feng Xiang-hong | السنةسنة = 2002 | العنوانعنوان = New evidence on the anatomy and phylogeny of the earliest vertebrates | journalصحيفة = Proceedings of the Royal Society B: Biological Sciences | volumeالمجلد = 269 | issueالعدد = 1503 | الصفحاتصفحات = 1865–1869 | doi = 10.1098/rspb.2002.2104 | المسارمسار = http://journals.royalsociety.org/index/JA88X875KH2VC0E8.pdf|التنسيقتنسيق=PDF | pmid = 12350247 | pmc = 1691108 | postscript = <!--None-->}}</ref>}}
| excludes = [[فكيات]]<ref>''[[Edwinإدوين Harrisإتش Colbert|Colbert, E.H.كولبيرت]] & Morales, M. (2001): [[Evolution of the Vertebrates|Colbert's Evolution of the Vertebrates: A History of the Backboned Animals Through Time]]''. 4th edition. John Wiley & Sons, Inc, New York - ISBN 978-0-471-38461-8.</ref>
