Talk:Synapsida/Archive 1

Article merged: See old talk-page here

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

What "fused arch", synapsid refers to the number and placement of temporal openings in the skull; one, low on either side as opposed to two in the reptilian diapsida. Another word for apsis is fenestra. In much the same sense, a syncline is a down warp in folded strata.

I known, the standard place for the latest entry is at the bottom where it will get the least attention. If putting it at the top torques anyone to much, go ahead the synplace it. J.H.McDonnell (talk) 23:21, 12 September 2010 (UTC)

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)

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)

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)

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)

"Some synapsids (including mammals) also have a warm-blooded metabolism, even though early synapsids, such as pelycosaurs, were most certainly cold-blooded." In British English, "most certainly" means "definitely". In US English (I think) it means "almost certainly" (i.e. probably). Which meaning is intended here? Wardog (talk) 10:07, 15 January 2009 (UTC)

I suspect that this was a typo. I've changed it to "early synapsids, such as pelycosaurs, are believed to have been cold-blooded."
We might very well want to cite this.
AFAIK, "most certainly" is not normally used in US English to mean "almost certainly" / "probably".
(I see that the expression "most certainly" occurs over 400 times in Wikipedia articles, and it looks like most of those would be clearer if rephrased.) -- 201.37.230.43 (talk) 16:14, 5 February 2009 (UTC)

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)

Isn't traditionally Synapsida one of three subclasses of Reptilia? Petter Bøckman (talk) 13:43, 2 June 2009 (UTC)

One of four traditional subclasses, yes. Romer's scheme divided reptiles into Anapsida, Diapsida, Synapsida, and Euryapsida (which turned out to be polyphyletic). Dinoguy2 (talk) 16:52, 2 June 2009 (UTC)

I suppose Synapsida as a class is from Benton? Petter Bøckman (talk) 19:55, 2 June 2009 (UTC)

He may have been the first to make Synapsida a class but I'm not sure. He's one of the few vert paleo workers that's even using ranks anymore, so it wouldn't surprise me. Dinoguy2 (talk) 23:01, 2 June 2009 (UTC)

The article can't seem to decide whether the mammalia are contained in the synapsida, or the synapsida are paraphyletic. Please make a choice and stick to it, because as it stands it's just contradictory and confusing. If notable alternative classifications exist, relegate them to a footnote. Shinobu (talk) 05:07, 27 December 2008 (UTC)

Which part specifically is contradictory or confusing? Dinoguy2 (talk) 15:03, 27 December 2008 (UTC)

There is very unfortunately no consensus on this sort of thing and this page reflects the opinions of taxonomists. Innotata 21:34, 26 October 2009 (UTC) —Preceding unsigned comment added by Innotata (talk • contribs)

This section has seen some re-writing, but still only make sense to those intimately familiar with the various bones of the primitive tetrapod skull. I think the only way to get the point across to the general public is through illustrations. Petter Bøckman (talk) 20:38, 17 December 2009 (UTC)

Do we really want to include the idea that limb posture in some way indicates metabolism? I mean, yes, it's an idea from the scientific literature, but it's a pretty damned stupid one, with zero support beyond a correlation based on an N=2 and no legitimate biomechanical justification that I'm aware of. Mokele (talk) 03:19, 3 February 2010 (UTC)

Don't blame me, blame Benton. N is 3 anyway (Reptiles, birds and mammals), and posture says something about mode of running/walking, which is obviously tied to metabolism. When I get better time, I'll cite the curled up Thrinaxodons. What buggs me is that I haven't been able to track down the two alleged skin imprints (skutes and fur respectively). I see them mentioned here and there, but never with a traceable citation. Petter Bøckman (talk) 08:33, 3 February 2010 (UTC)

EDIT: Comming to think of it, this theory hangs on the thecodontts. They had an erect pose, were they homeotherms or semi-homoetherms in any way? Hm, hm, hm Petter Bøckman (talk) 14:29, 3 February 2010 (UTC)

That's the thing - just because synapsids became more erect during the same time they became endotherms doesn't mean erect stance indicates endothermy. Hell, you can say the same thing about fur, since I have a hard time believing insulation was a major issue in the baking heat of the Permian desert or swamp. Studies on extant organisms show that "sprawling" lizards have the same net cost of transport (calories/meter) as mammals of the same size, and the primary problem with sprawling limbs (muscular effort to maintain posture) shows up in the highly-crouched limbs of most small mammals. Now, there's a fair possibility that posture controls speed for larger animals, because bone is weaker in torsion than in bending, but even that's dubious for a link to endothermy (plenty of ectotherms are quite fast, and anything smaller than a dog has a high bone safety factor regardless of metabolism).

In general, I'm wary of inferring metabolism from gross skeletal morphology, precisely because we have such a limited data set, but also because data on extant animals simply doesn't support some of the claims being made, particularly with regard to locomotion "efficiency" (the mis-use of which in locomotion is a pet peeve of mine). I think it's fair to note the increasingly erect posture, but we should either omit the implication about metbolism, or include a reference on modern studies showing the lack of difference between mammals and lizards of the same size (random trivia fact - snakes *also* have the same cost of transport as mammals & lizards when the snake is laterally undulating, so limbs *really* don't matter). Mokele (talk) 16:52, 3 February 2010 (UTC)

Are those values for ordinary walking speed, or do they include running? Sprawling gait leads to a sideways swinging backbone, and the mass that moves sideways when a big goanna or a crocodile walks is substantial. When they run, I would think they would need energy to counter the effect of sideways mass movement? I would assume the same to be true for a Dimetrodon, Walking with Monsters (episode II) has a very good reconstruction of one running. Or are we now in the land of original research/speculation here? Petter Bøckman (talk) 17:52, 3 February 2010 (UTC)

This page contains a lot of jargon making it difficult to follow, or possibly just too many synonyms in the introduction. It needs to have a more succinct introduction that is easier for someone unfamiliar with the topic. For instance:

"Primitive synapsids are usually called pelycosaurs; more advanced mammal-like ones, therapsids. The non-mammalian members are described as mammal-like reptiles in classical systematics,[2][3] but are referred to as "stem-mammals" or "proto-mammals" under cladistic terminology."

Are primitive ones more reptile-like? What is going on in the second sentence? Where is the part that says what makes it reptile-like and where is the part where it says it's mammal like if the page redirects from that entry? —Preceding unsigned comment added by 98.237.245.25 (talk) 08:04, 17 July 2010 (UTC)

You are right. The problem here is that this article is right in the middle of the battleground between cladistical and Linnaean nomenklature. I'll have a look at it. --Petter Bøckman (talk) 10:47, 17 July 2010 (UTC)

I've tried to clear it up, see if it is better now.--Petter Bøckman (talk) 06:01, 19 July 2010 (UTC)

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)

Don't get stuck on the limiting rules of cladistics. Paraphyletic groups , or taxa, are perfectly fine even if they don't fall ideally in the cladistic scheme of things. If you want to designate them with an asterisk, ok by me. Cladistics and normal (traditionl) taxonomy view things from different perspectives, cladistics from the point of view of evolutionary continua, traditional taxomomy from the prespective of broader and broader moprhologic similarities (heiracharal taxa). The use of one doesn't (or at least shouldn't) invalidate the other.

As for those pesky paraphyletic groups that some seem to have a problem with, whether "valid" or not, they are certainly usefull. Cladistic sequences in which there are no ranks should be distingushed from ordinary taxonomic hierarchies or sequences in which derived taxa can take on rank equal to or greater than their immediate predicessor; such as having Class Mammalia derived from suborder Cynodontia (which make perfectly good taxonomic even if not cladistic sense) . J.H.McDonnell (talk) 23:26, 12 September 2010 (UTC) —Preceding unsigned comment added by J.H.McDonnell (talk • contribs) 00:04, 30 July 2008 (UTC)

In "Evolutionary History" section there is this piece of information:

"Today, there are 5,400 species of living synapsids known as the mammals, including both aquatic (whales) and flying (bats) species, and the largest animal ever known to have existed (the blue whale)."

Well, the Amphicoelias fragilimus was far bigger than the blue whale, reaching 40 to 60 meters. — Preceding unsigned comment added by 186.212.123.245 (talk) 15:25, 5 July 2011 (UTC)

Not by mass, though. Abyssal (talk) 20:28, 7 July 2011 (UTC)

The intro states: "In the form of mammals, synapsids (most recently and notably humans) again became the dominant land animals after they outcompeted birds following the Cretaceous–Paleogene extinction event" - but is this true? Before the rise of intelligent humanoid great apes 3m years ago, by what measure were mammals dominant over birds? Geographical range? (No) Numerical occurrence? (No) Intelligence? (Barely - corvids vs primates). Arguably archosaurs and their descendants dominated the world from the mid-Triassic until the rise of humans... Fig (talk) 10:52, 7 May 2012 (UTC)

In what way were archosaurs ever dominant over insects? The whole idea of "dominant land animals" is a holdover from the old scala naturae days. At best, we could talk about dominant vertebrate megafauna (i.e. which clade of animals filled most of the large charismatic herbivore and carnivore niches). MMartyniuk (talk) 15:31, 7 May 2012 (UTC)

As Martin says it means to represent all or nearly all megafauna (particularly on the carnivorous side), the critters you'd notice first if you stepped into the period in question. For fossil it's what big bones you first spots in the fossil beds. It has nothing to do with number of species or biomass or anything like that. If it did, I suppose we'd say roundworms are dominating the fauna. It is an expression like "evolutionary trend" which conveys a lot of meaning in a short phrase, but require an exceptionally steady hand to use properly.Petter Bøckman (talk) 19:52, 7 May 2012 (UTC)

MMartyniuk neatly captures the problem when he uses the term "charismatic", an obviously unscientific term, in defining dominant vertebrate megafauna. In biology, the word "dominant" can be used for alleles or for status in a herd or pack; it should not be used for taxa unless it really refers to numerical abundance.

There's another problem: the word "outcompete". It does have a bona fide use: rodents outcompeted multituberculates in the Eocene. But mammals and birds? Considering that there are more than half again as many species of birds than of mammals, it's pretty hard to think of an arena in which mammals outcompeted birds.

Peter M. Brown (talk) 20:43, 7 May 2012 (UTC)

We can easily get around the problem by specifying that we are referring to the large animals here. The same phrase is used in botany without hick-ups, like "conifers dominate the boral forests" (size dominance) or "the forest floor vegetation is dominated by grasses" (number dominance), so there's really not necessarily a question of being charismatic (unless one like grasses very much).

As for outcompeting, it would only be a relevant factor in the case where the two groups are competing over the same niches. It has been argued that mammals (particularly placentals) have outcompeted birds as terrestrial megafauna (terror birds, elephant birds), a stance which I guess have merit. Birds on the other hand very clearly dominate aerial vertebrate fauna, so I would guess it's more a question of niche segregation rather than downright outcompeting. Petter Bøckman (talk) 06:54, 8 May 2012 (UTC)

Qualifying talk of outcompeting by specifying niches would be unwieldy. I have accordingly deleted that language. In the interest of neutrality, I have also replaced "dominant" by "largest"; there are clearly differing viewpoints on the matter. Peter M. Brown (talk) 14:35, 8 May 2012 (UTC)

Referring to "Triassic and Jurassic ancestors of living mammals", the section Synapsid#Evolutionary history has contained the sentence:

"Rather than outrunning predators, they are believed to have adapted the strategy of outmaneuvering predators using their improved locomotor capabilities."

The source given is Hoyt, 1997, now a dead link. I have communicated with Dr. Hoyt (Donald F. Hoyt, Professor Emeritus at Cal Poly Pomona), who makes quite clear that this page is not to be used as a reliable source for Wikipedia purposes. As no other source is provided for the claim, I am deleting the sentence as well as the citation. I am also deleting the claim that the animals in question were "able to change direction more quickly to catch small prey at a faster rate," as no source other than the Hoyt link is provided. Peter Brown (talk) 19:46, 24 October 2012 (UTC)

When I read an article like this, I think how detailed discoveries and deductions are making paleontology a beautiful body of knowledge. Well done! Tsinfandel (talk) 13:40, 7 May 2013 (UTC)

"Synapsid" may indeed be translated as "[having a] fused arch" (syn+hapsis). But I wonder how "theropsid" or "sauropsid" can be argued to translate as "beast-faced" and "lizard-faced", as claimed not only here but also at Reptile? Is the idea ther+ops+id? So the "psid" element has two completely unrelated origins? Perhaps there can be anything like a source or reference as to the origin, historical sequence and actual meaning of these names? Also, it should be sorted out which plural should be used. Is it "Synapsida" or "synapsids"? Atm the articles seem to freely mix it up, Therapsida goes as far as beginning with "Therapsida is a group of synapsids". The article resides at Therapsida, while Synapsida redirects to Synapsid. I have no idea which is preferable or recommended, but whichever it is, it should be documented. --dab (𒁳) 09:11, 15 January 2014 (UTC)

A synapsid is a member of the group Synapsida just as a dinosaur is a member of the group Dinosauria and a primate is a member of the group Primates. Generally wiki articles use the formal taxon name and in rare cases the "common name" like usage. There doesn't seem to be much consistency here.

"psid" is not the root of the word, "ops or "aps" is which are two different words. "Aps" = arch, "ops" = face. Syn = fused aps = arch id= group suffix. Saur = lizard ops = face -id= group suffix. Triceratops = three horned face. Triceratapsis would mean three horned arch. MMartyniuk (talk) 14:38, 15 January 2014 (UTC)

Do you have a good ref? It could be useful to have in the article. Petter Bøckman (talk) 21:24, 15 January 2014 (UTC)

No ref, just basic knowledge of Greek/Latin roots. I'm sure a ref could be dug up form somewhere listing the etymology. MMartyniuk (talk) 13:05, 16 January 2014 (UTC)

MMartyniuk is probably right, I came to the same conclusion, but this is based on the information that Synapsid = "fused arch", Theropsid = "beast-faced". If we treat this information as a given, we are forced to assume that the names are from haps- "arch" and ops- "face". The question is, is the information in the article already based on second-guessing the meanings, or is it somehow based on something published by the people who came up with the names?

Also, if Theropsid (Goodrich, 1916) = "beast-faced", and Synapsid (Osborn, 1903) = "fused-arch", what is the meaning of Therapsid (Broom, 1905)? Perhaps "beast arch"?

If the sources given for the names are correct (do we need any reference for "Goodrich 1916", or is this itself a reference? How do I consult this reference?), the sequence of naming is Synapsid (1903), then Therapsid (1905) and finally Theropsid (1916). So apparently the name Therapsid would have been based on the name Synapsid, but how? --dab (𒁳) 10:15, 17 January 2014 (UTC)

The fact that this entire article is a mess of unverified/sourced claims and original synthesis is a whole separate issue from the etymology thing... the first two sections of "Characteristics" are entirely unsourced. MMartyniuk (talk) 13:14, 17 January 2014 (UTC)

Re: etymology - Therapsida was named in this paper, which does not provide etymology. Goodrich, 1916 is this paper, which does not seem to provide etymology of Theropsida, either.--Macrochelys (talk) 21:05, 17 January 2014 (UTC)

... I should correct myself, though, that the name Theropsida actually shows up in papers that predate Goodrich's 1916 paper. The actual author of the name seems to be Harry Govier Seeley, who used it for the proposed group containing anomodonts and monotremes; and the original paper naming the group appears to be this one, published in 1895 in Proceeding of the Royal Society of London. Etymology of the name name was not provided there, either.--Macrochelys (talk) 20:22, 8 March 2014 (UTC)

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)

Synapsids are not reptiles, so the term "mammal-like reptiles" is a misnomer and should be discouraged. Nonetheless, said misnomer is common, at least in older texts, so I am okay with said redirect.--Solomonfromfinland (talk) 22:29, 8 December 2015 (UTC)