Talk:Amniote
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[edit] The urinary bladder and allantois
"The bladder of amphibians is thought to be homologous with the allantois (a fetal excretory organ) of amniotes. The bladder of turtles, Sphenodon and some lizards is formed by retention of part of the fetal allantois. Bladders are absent in crocodilians, snakes, some lizards, and most birds, because the urine of these is semisolid, consisting mostly of uric acid. In mammals the bladder is formed from part of the allantois and from the urodeum (a subdivision of the cloaca). The bladder empties into the cloaca in tetrapods except for therian mammals, in which it has a separate external opening called the urethra."
http://www.lifesci.utexas.edu/courses/bio478L/LecturesPDF/kidney.pdf.
"The bladder and the urethra develop from the urogenital sinus. The bladdder also develops in part from the allantois. The hindgut and the allantois empty into the cloaca early in development. The cloaca ends as the cloacal plate, a region of ectoderm and endoderm without intervening mesoderm. The urorectal septum develops in that region of the cloaca where the allantois and the hindgut meet. This septum grows toward the cloacal plate and divides it into an anal canal and a urogenital sinus. The cloacal plate then gets divided into an anal membrane and a urogenital membrane with a perineal body in between. The mesonephric duct empties into the urogenital sinus. The urogenital sinus and the allantois enlarge to form the urinary bladder."
http://isc.temple.edu/marino/embryology/Kidney98/kidney_text.htm
As far as I can see, the allantois does contribute to the formation of the urinary bladder in amniotes.
[edit] Microphylum?
Is there a published reference for referring Aminota to the rank of Microphylum? If so, it should be listed and discussed in the text, especially as I've seen this being migrated to taxoboxes on other pages.Dinoguy2 22:01, 17 August 2006 (UTC)
- Amniota is the name of a clade. I don't see how it can be forced to fit into taxoboxes, which are based on a more traditional classification scheme. Other than this item in a forum of some kind, the only references I can find for 'microphylum' in the sense used in the taxoboxes are on Wikipedia or derived from Wikipedia. It looks like a neologism to me, complicated by the fact that 'microphylum' and 'microphyllum' are used as species names. -- Donald Albury(Talk) 21:58, 18 August 2006 (UTC)
- To be fair, Amniota was coined before the advent of phylogenetic taxonomy, so it is not only a clade. I'm not sure what it's traditional rank would be, though Benton (2004) lists it as "Series". I prefer leaving it unranked, as Benton tends to use a lot of superfluous ranks.Dinoguy2 23:53, 18 August 2006 (UTC)
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- And in any case, calling 'Amniota' a 'microphylum' looks like a real problem. I cannot find any instance of 'microphylum' and 'Amniota' on the same web page in a Google search that is not in WP or copied from WP. I'm going to bring this up over at Wikipedia talk:WikiProject Tree of Life. -- Donald Albury(Talk) 11:11, 19 August 2006 (UTC)
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- Note--the forum you linked, Dalbury, is the Dinosaur mailing List. While an amazing resource, there is a lot of original research that goes on (good thing for paleontologists, bad thing for an encyclopedia). The use of microphylum there is, within the context of the post, definately original research. I've seen similar examples of the author's shoehorning cladistic research into Linnean ranks on the internet before, and I suspect this is how the use of microphylum, etc., came about.Dinoguy2 03:09, 20 August 2006 (UTC)
- I removed the reference to microphylum from the article. If there is a classification out there that applies that rank to amniotes, "microphylum" could be mentioned in the context of that classification, but it's confusing to have such an obscure rank in the article's first sentence.
[edit] Problem with Taxonomy section
The Taxonomy section shows the Class Synasida containing the Order Therapsida, which in turn contains the Class Mammalia. You really can't mix traditional classification and cladistics this way.This needs to organized like Synapsid is. -- Donald Albury 22:55, 5 February 2007 (UTC)
- Fixed it. Dinoguy2 23:01, 5 February 2007 (UTC)
[edit] No phylogram of amniotes?!
Erm, we need one. Badly. Samsara (talk • contribs) 14:45, 3 June 2007 (UTC)
- Do-dom: http://www.tolweb.org/Amniota Samsara (talk • contribs) 14:49, 3 June 2007 (UTC)
[edit] Are amniotes a polyphyletic group?
Based on this and related articles, it seems that synapsids and sauropsids are two different lineages of amniotes which have evolved separately and are not directly related to one another. This means that "amniota" is a polyphyletic group, and therefore it is not a valid clade by the standards of modern cladistics. Is this correct? —Preceding unsigned comment added by 79.179.255.83 (talk) 15:26, 29 March 2008 (UTC)
