Talk:Anapsid

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Comments[edit]

Um, the turtle entry says "However, it has recently been suggested that the anapsid condition of the turtle skull may not be a primitive character reflecting anapsid descent, but rather a case of convergent evolution. More recent phylogenetic studies with this in mind have placed turtles firmly within diapsids, slightly closer to Squamata than to Archosauria. All molecular studies have strongly upheld this new phylogeny, though some place turtles closer to Archosauria. Re-analysis of prior phylogenies that affirmed an anapsid ancestry suggests that their inclusion of turtles within Anapsida was due to both the starting assumption that they were anapsid (most prior phylogenies concerned what sort of anapsid they were) and also due to insufficiently broad sampling of fossil and extant taxa for construction of the cladogram. While the issue is far from resolved, most scientists now lean towards a Diapsid origin for turtles."

To which must be added that the molecular evolution of turtles is MUCH slower than that of other "reptiles" (Mol.Biol.Evol. 9 p457: 0.25%/1 mya in turtle mtDNA vs. 2%/1 mya for most amniotes). It would have to be checked whether the studies placing turtles in the Diapsida take this into account, as an uncritical assumption that rates of molecular evolution of turtles and classical diapsids are the same would give the wrong impression of a much closer relationship than there actually is... it is only as of recently that we find out that the rates of molecular evolution may vary by an order of magnitude. Generally, long-lived taxa with slow metabolism usually fall below the "2%" rule-of-thumb, for example in albatrosses the actual value is around 1% etc. Unfortunately, seriously calibrating molecular evolution rates requires a good subfossil record for ancient DNA extraction and some guesswork, and may thus not be properly possible for slowly-evolving sequences at all. Until multi-gene supertrees become SOP, higher-level molecular taxonomies are potentially fraught with error (it is entirely possible to "assign" the platypus to the Eutheria if one chooses the wrong sequences, for example). For comparisons between genera and closely related families, molecular taxonomy works best and is very reliable, above and below that, molecular taxonomy is essentially a developing technology)

An important point, however, is that molecular studies can raise issues that would have been overlooked otherwise. With the suggestion that the anapsid condition of turtles is secondarily derived, palaeontological research should focus on verifying or falsifying this. As it was assumed that the anapsid condition did only develop once, the precise nature of this condition was not sufficiently checked to determine whether is is an plesiomorphy or a homoplasy in turtles. If turtles are secondarily anapsid, the layout and development of the temporal bones can be expected to be noticeably different from anapsids proper. Dysmorodrepanis 15:15, 25 April 2006 (UTC)[reply]

Regarding testudines article[edit]

The article states that "The main article about Testudines covers the debate about their ancestry". It doesn't at the moment. —Preceding unsigned comment added by Causantin (talk • contribs) 15:06, 28 September 2007 (UTC)[reply]

Image:Skull_anapsida_1.png[edit]

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Turtles are not Anapsid[edit]

They are Diapsid. Image use is misleading 99.236.221.124 (talk) 07:38, 9 April 2010 (UTC)[reply]

Read the text. While "anapsida" probably isn't a valid taxonomic group, and turtles are derived diapsids, turtles *do* have the anapsid skull condition. Mokele (talk) 12:09, 9 April 2010 (UTC)[reply]

I believe that Anapsida is a valid taxonomic group, but it needs to get rid of regressive Synapsids and Diapsids to work. It should only include the animals who were originally Anapsid. 62.198.162.25 (talk) 07:57, 19 November 2013 (UTC)[reply]

Polyphyletic[edit]

The anapsids are a wastebasket taxon.

71.164.209.66 (talk) 21:17, 29 July 2012 (UTC)Anonymous[reply]

It should be redesigned so it only contains true Anapsids, I.E, the animals who originally only had no temporal openings. What has made this subclass a joke is including regressive Anapsids, such as Turtles and Mosasaurs, who are not Anapsids, but either Diapsids or Synapsids who regressed to an Anapsid state.

We should use the Anapsid subclass the way it is meant to. To classify the early Amniotes who did not have a temporal lobe. Not the regressive ones, who should be put into their respective subclasses, I.E, Synapsid or Diapsid. 62.198.162.25 (talk) 07:55, 19 November 2013 (UTC)[reply]

Parareptiles[edit]

The taxobox says that parareptiles are an order of anapsid, with testudines within parareptilia. Where does this come from? Regardless of whether testudines are anapsids or diapsids, I can't find any other claim that parareptiles are anapsids, or testudines are parareptiles. 62.172.108.24 (talk) 09:25, 30 June 2015 (UTC)[reply]

They aren't anapsids

Megaloguana (talk) 12:47, 24 February 2016 (UTC)[reply]

Phylogenetic position of turtles -citation needed[edit]

I have asserted that the "reanalysis of prior phylogenies" needs a citation because the text implies carelessness on the part of the investigators, whereas it could be that the molecular techniques for classification simply hadn't been developed at the time. Casu Marzu (talk) 14:57, 4 March 2017 (UTC)[reply]