Anaspida

For the reptile group, see Anapsida. For the gastropod clade, see Anaspidea. For the freshwater crustacean family, see Anaspididae.

Anaspida
Temporal range: 444–358.9 Ma early Silurian - Late Devonian
Cowielepis
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Superclass: †Anaspidomorphi
Class: †Anaspida
Traquair, 1899
Type species
†Birkenia elegans
Traquair 1898
Orders
Synonyms
  • Anaspidi
  • Birkeniae
Anaspids are characterized by a large, tri-radiate spine (red) posteriorly to the series of branchial openings. It is assumed that the most primitive anaspids, such as Pharyngolepis (top), possessed a long, ribbon-shaped, ventrolateral fin-fold (green). More advanced forms, such as Rhyncholepis (bottom), possessed a shorter paired fin-fold (green) and enlarged, spine-shaped, median dorsal scutes. – Philippe Janvier[1]

Anaspida ("shieldless ones") is an extinct group of jawless fish that existed from the early Silurian period to the late Devonian period.[2] They were classically regarded as the ancestors of lampreys,[3] but it is denied in recent phylogenetic analysis,[4] although some analysis show these group would be at least related.[5] Anaspids were small marine fish that lacked a heavy bony shield and paired fins, but were distinctively hypocercal.

  1. ^ Janvier, Philippe (1997) Anaspida The Tree of Life Web Project.
  2. ^ Ahlberg, Per Erik (2001). Major events in early vertebrate evolution: palaeontology, phylogeny, genetics, and development. Washington, DC: Taylor & Francis. p. 188. ISBN 0-415-23370-4.
  3. ^ Patterson, Colin (1987). Molecules and morphology in evolution: conflict or compromise?. Cambridge, UK: Cambridge University Press. p. 142. ISBN 0-521-32271-5.
  4. ^ Keating, Joseph N.; Donoghue, Philip C. J. (2016-03-16). "Histology and affinity of anaspids, and the early evolution of the vertebrate dermal skeleton". Proceedings of the Royal Society B: Biological Sciences. 283 (1826): 20152917. doi:10.1098/rspb.2015.2917. ISSN 0962-8452. PMC 4810860.
  5. ^ Cite error: The named reference :0 was invoked but never defined (see the help page).