Talk:Synapsid

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Article merged: See old talk-page here

I previously added the mammalia class, which was ommited I think in this section

Contents

[edit] Missing items in taxobox

The subgroups of pelycosaurs and caseasaurs are covered in the text. Ought these not to be included in the taxobox as well? (I would add them myself, but I know little of the science of taxonomy and might easily do something stupid, so I would prefer to leave it to someone who knows what they are doing.) SpectrumDT 19:41, 22 October 2005 (UTC)

This page says there are 4500 species of mammals but the page on mammals says there are 5500. Which is right? Smeapancol 19:14, 7 January 2006 (UTC)

[edit] "believed to have been caused by poisonous volcanic gas"

Surely there are a whole range of theories on the causes of the Permian-Triassic event —This unsigned comment was added by 82.23.1.206 (talk • contribs) 23:45, 1 April 2006.

You're right. I've edited the article to reflect the ambiguity. bcasterline t 00:47, 2 April 2006 (UTC)

[edit] Clasification + Phylogeny

I've switched the classification scheme we had into two parts- classification and taxonomy. This seems to work a bit better aesthetically, as it removes unranked taxa from the ranked list, and presents an unambiguous cladogram to better reflect evolutionary relationships. I welcome discussion on this, and will accept if it's met with universal hatred and gets reverted :) Dinoguy2 20:02, 25 May 2006 (UTC)

I love it... ;-) Fedor 12:52, 6 September 2006 (UTC)


"Mammal-like reptiles" ??? Synapsids include mammals. Someone plese look into this. —Preceding unsigned comment added by 202.78.232.177 (talk • contribs) 22:16, 9 January 2007 202.78.232.177

The key here is 'traditionally'. Traditionally Synapsids did not include mammals, but were treated as a subclass of Reptilia. Hopefully, use of the word 'traditionally' implies that this is an outdated term. Dinoguy2 19:48, 10 January 2007 (UTC)

I think i should combine mammals with synapsids. Because they're in the same class right? We should do the same thing with birds put into reptiles. User:4444hhhh

I don't think they've ever been put in the same class. Synapsids, in phylogenetic taxonomy, include mammals, but this system does not use any kind of ranks. Traditionally, Synapsids have been ranked as a Subclass of Class Reptilia. More recently, Benton ranked them as a Class seperate from reptiles and paraphyletic with respect to mammals (that is, it doesn't include mammals, because they were kept in a seperate class. As far as I know, creating a class that includes all synapsids would be original research. Same for reptiles and birds, though a new class is sometimes used for dinosaurs and birds, usually either Dinosauria or Archosauria. But the dinosaur wikiproject has decided to use Benton's scheme for them as well, and he uses Class Sauropsida for reptiles and class Aves for birds. Dinoguy2 03:02, 21 March 2007 (UTC)

[edit] Non-Mammal Synapsid

Are there any existant non-mammal synapsids? -- 20:22, 26 August 2007 (UTC)

I think it's safe to say that all non-mammal synapsids are extinct. See Evolution of mammals, which notes in the intro: “From the point of view of cladistics, mammals are the only surviving synapsids.” --Mathew5000 21:29, 26 August 2007 (UTC)

[edit] Shouldn't humans be listed as well here?

Since mammals evolved from therapsids and we humans are mammals, I believe we should be listed under the current living synapsids of today. Suffor 14:46, 1 September 2007 (UTC)

Note that synapsids as they are treated here are paraphyletc--that is, they expressly exclude the mammals. That's what the * means in the taxobox, for example. Dinoguy2 14:50, 1 September 2007 (UTC)
Actually, the article's intro expressly includes mammals as synapsids. --Mathew5000 17:11, 1 September 2007 (UTC)

[edit] Mammal-like reptiles

4444hhhh, I noticed you redirected Mammal-like reptiles to this page. While my pro-merger arguments on the other article's talk page have not been answered, I do believe this material should not be lost but properly merged in, for the reasons which I stated there. If you want to do it, be my guest, otherwise I will have a go at it myself. Gnostrat (talk) 03:36, 20 January 2008 (UTC)

Er... I'm dinoguy, not synapsidguy, but doesn't (didn't) the term 'mammal-like reptile' refer to therapsids specifically? I've never heard Dimetrodon or Edaphosaurus referred to that way. The term you're looking for is 'stem-mammal.' Dinoguy2 (talk) 03:19, 18 March 2008 (UTC)

Well mammal like reptile is an old term anyway, i suppose though that it reffered to all synapsids (including non therapsids like Dimetrodon) apart from true mammals (they are a different class) are mammal like repitiles.Lemming42 (talk) 20:04, 18 March 2008 (UTC)
I could be wrong, but I presume a stem-mammal is an actual mammal which diverged earlier than the last common ancestor shared by the crown-group (i.e. monotremes plus therians). If it's a fossil synapsid that didn't even fulfill the classic criterion for inclusion in Mammalia — the single dominant jaw joint between dentary and squamosal — it can't be called a stem-mammal. One suggestion (can't remember whose) was to call the non-mammalian members paramammals.
I know of a single site (Palaeos) that describes therapsids, but not pelycosaurs, as "mammal-like reptiles". It's an excellent resource in nearly every way, but I think it's mistaken in this overly restricted usage (and see here for a site that takes the opposite view from Palaeos). Mammal-like characters emerged by stages including, for example, the appearance of differentiated teeth in sphenacodontids like Dimetrodon. Classic works from at least the 1960s to the present (Romer, Carroll, Benton) all refer to pelycosaurs and therapsids together as the (so-called) "mammal-like reptiles". Gnostrat (talk) 21:35, 18 March 2008 (UTC)
Ok, if those authors used it that way that's good enough for me (though this should be cited, the use of mammal-like reptile is currently unsourced). Actually all the citations could use an overhaul, many are incomplete and mixed in with notes that could really be worked into the main text, to conform with the style and layout of similar articles. As for stem-mammal, I was using it in the PhyloCode sense--i.e., all members of a clade excluding the crown clade. So "stem mammal" would mean any synapsid that is not a member of monotremes+marsupials+placentals. Dinoguy2 (talk) 00:00, 19 March 2008 (UTC)
The PhyloCode is fatally flawed, and I now have cause to hate it even more! If you are right, under the PhyloCode a "stem-mammal" could mean either (1) a mammal that isn't in the crown-group, or, amazingly, (2) a synapsid that isn't even a mammal. Well, Carroll (1988) did suggest, half-seriously, that all synapsids might be incorporated into the Class Mammalia, but I never imagined that a new code would turn a jest into a requirement. I had considered removing "stem-mammal" from the lead section (it's unsourced too) but now I guess I will have to leave it in and request some confirmation.
Anyway, I'll be adding citations for "mammal-like reptiles" and fix up the notes (one of them is superfluous, in fact). There's just a couple of them that are citing an entire article, but they're short articles and I imagine that will suffice until somebody can put in some specific page references. Gnostrat (talk) 09:34, 19 March 2008 (UTC)
Sorted the citations, though there are still too few of them so if some experts could muck in, that'd be great. Come on guys, you had to use sources when you first wrote this stuff. By the way, Dinoguy, I bet you don't refer to dinosaurs as "stem-birds", do you? : ) Gnostrat (talk) 21:53, 22 March 2008 (UTC)

[edit] Changing classifications

I've removed the following paragraph from the above-named section and I'm putting it here for further discussion. Perhaps it could be reinserted after it's been shortened and amended:

Most taxonomists who apply the caladistic approach consider tetrapods to fall within the Sarcopterygian Class (making Synapsida an Infraclass within the Class Sarcopterygii). The classification of this article takes somewhat of a traditional approach, considering tetrapods to be a sister group to the Sarcopterygians, whereas most authorities consider tetrapods to be descendents of Sarcopterygian fish. In the classification table to the upper right, notice the names that have an asterisk (*) denoting that they are paraphyletic groups. Paraphyletic groups are not a quality of the cladistic approach to taxonomy.

I substantially agree with this, but do you think that this page is the appropriate place to argue the case? We don't write essays here, and it's only tangentially related to the subject of this article. Besides, if Sarcopterygii were ranked as a class, Synapsida would rank considerably lower than an infraclass. (I.e. Sarcopterygii > Rhipidistia > Tetrapodomorpha > Tetrapoda > Neotetrapoda > Reptiliomorpha > Cotylosauria > Amniota > Synapsida). Nobody would like to get these clades ranked in a coherent hierarchy better than I would, but we do need some sort of taxonomic consensus for that before we can put it on Wikipedia : ) Gnostrat (talk) 02:34, 7 March 2008 (UTC)

[edit] Mammals as Synapsids

The article implies and states several times that mammals are synapsids. However, as synapsida and mammalia are both classes, I don't see how they can coexist like that. Can somebody clarify this?

Also, are there any extant synapsids, or are they all extinct? Asriel (talk) 12:41, 11 May 2008 (UTC)

Well mammals are synapsids. So as for extant synapsids go, you are one! The taxonomy of Synapsida and Mammalia is confusing as Wikipedia uses that of Benton (2004). Mike intentionally made Class Synapsida paraphyletic, so Class Mammalia does not fall within Synapsida. Strange but true. However, trying to create a rank-based taxonomy with Mammalia within Synapsida would suffer from an exceptional growth in taxonomic ranks about the Class level. For now, its a good compromise Mark t young (talk) 15:25, 11 May 2008 (UTC)
I'll just add that the section on 'Changing Classifications' explains it. Phylogenetically considered, mammals are synapsids. Nobody disagrees with that, but the formal ranking of Mammalia as a class in its own right is traditional, going back to Linnaeus himself. It's the old problem of fitting the fossils into a classification originally devised for living animals. Linnaeus' groupings have been changed before, of course, and I understand there have been proposals to formally demote the mammals to a subgroup of Synapsida. It would indeed require inserting lots of new ranks in between Class Synapsida and the living orders of mammals, but it could be done, and would probably look something like this:
  • Class Synapsida
    • Subclass Eupelycosauria
      • Infraclass Sphenacodontia
        • Division Therapsida
          • Legion Mammalia
More's the pity that we can't do it like that on Wikipedia. But we can't invent classifications, we can only report them, and for any major shakeup of Wikipedia's classification I guess we have to wait until there's some sort of consensus for change among taxonomists, or at least make a decision to go with some other scheme that's at least as authoritative as Benton's. In the meantime, we're left with this awkward compromise of a clade Synapsida that includes mammals, but a class Synapsida that doesn't. Just to annoy you (well, it annoys me), I should point out that there's a very vocal school of taxonomy which, far from putting its energy into necessary improvements to the accepted Linnaean classification, is campaigning instead to sweep it away, ranks and all.
Short answer on extant synapsids: they're called mammals. All the others are extinct, though. More precisely: if you run into a Moschops on your travels, the entire zoological community will beat a path to your door. Gnostrat (talk) 16:02, 11 May 2008 (UTC)