| Anamniotes | ||||
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 Trouts spawning showing typical anamniote external fertilization
 Anamniotes have a distinct larval stag, here a smooth newt
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The anamniotes are a group of vertebrates that lack the amnion during fetal development. These animals are not able to have embryos that develop on land, thus they lay their eggs in water exclusively.[1] The group contain the fishes and amphibians, the "lower" vertebrates, as opposed to the amniotes, the "higher" vertebrates.[2] [3]
The features unifying the anamniotes was first noted by Thomas Henry Huxley, who coined the phrase Ichtioid or Ichthyopsida ("fish-face") for the group.[4] The group representing an evolutionary grade rather than a clade, the term anamniote is now used as an informal way of denoting the physical property of the group, rather than as a systematic unit.
References
- ^ Colbert, E.H. & Morales, M. (2001): Colbert's Evolution of the Vertebrates: A History of the Backboned Animals Through Time. 4th edition. John Wiley & Sons, Inc, New York - ISBN 9780471384618.
- ^ Romer, A.S. & T.S. Parsons. 1977. The Vertebrate Body. 5th ed. Saunders, Philadelphia. (6th ed. 1985)
- ^ Nicholson, H.A. (1880): Manual of Zoology, Blackwood And Sons. Original text
- ^ Encyclopaedia Britannica, 9th ed. (1878). original text
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