Talk:Reptile/Archive 2

Shouldn't it say in the opening that birds are reptiles?

Seems like it's important to mention. ScienceApe (talk) 12:50, 2 November 2011 (UTC)

It is a question of definition. Under the traditional definition (the definition used in the article), birds are not reptiles, rather they (and mammals) have evolved from reptiles. There's no shortage of newer propositions of definitions of "Reptilia", with or without birds. This is abundantly covered in the classification section. Having said that, a sentence about in in the lede would do. perhaps:

The class Reptilia, covering the basal amniote stock have given rise to both the classes of birds and mammals. Thus under phylogenetic nomenclature, both are reptiles.

Would that do? Petter Bøckman (talk) 19:32, 2 November 2011 (UTC)

Do a majority of researchers still consider Synapsids to be reptiles? I'd leave mammals out of it, except in sections dealing with the history. Mammals are certainly not reptiles under phylogenetic nomenclature. MMartyniuk (talk) 12:42, 3 November 2011 (UTC)

Depends on how you apply the names. "Traditional" phylogenetic nomenclature did not used the name Reptilia (they have worked actively to get rid of it), so it's not surprising that you won't find any phylogenetic references for mammals being reptiles in disguise. The logic behind phylogenetic nomenclature is however forward enough: If reptiles are amniotes sans birds and mammals (the "common" interpretation), then obviously mammals are reptiles phylogenetically. The "mammals are not reptiles" (or "did not evolve from reptiles) stance is only viable under a crown group or node based definition anchored in living groups. Now, there are certainly no shortage of such definitions, though they usually use the name Sauropsida rather than Reptilia. I do agree that there's no explicit sources for mammals "being" reptiles though. What about:

The class Reptilia, covering the basal amniote stock have given rise to both the classes of birds and mammals. Birds are included in Reptilia under some phylogenetic definitions, see Sauropsida.

Better? Petter Bøckman (talk) 21:00, 3 November 2011 (UTC)

It may be best to split "Reptilia" from "Reptile." The Reptile article could then cover the classic reptiles, with appropriate mentions of taxonomic relationships to birds and dinosaurs. The Reptilia article could then cover explicitly the scientific/classification issues, and include birds and dinosaurs integrated within the article along with the classic reptiles. Rlendog (talk) 02:54, 20 December 2011 (UTC)

The article you propose for "Reptilia" is already covered under Sauropsida. The demarcation of the term Reptilia is very well covered in this article. Splitting "reptile" and "Reptilia" won't ad anything, particularly as we already have a Sauropsida article. I have edited the lede slightly to mention the other use of the term Reptilia. Petter Bøckman (talk) 08:20, 20 December 2011 (UTC)

You added "birds are included in Reptilia under some phylogenetic definitions." Are there any phylogenetic definitions of Reptilia that do not include birds? MMartyniuk (talk) 13:11, 20 December 2011 (UTC)

Your latest edit looks good to me, I like the rearrangement of the text too. Petter Bøckman (talk) 13:19, 20 December 2011 (UTC)

The third paragraph of the introduction (below the list) currently reads: "Reptiles are dinosaurs Aves (birds), which are not cold-blooded or scaly, are not included in this list." Obviously, something has gone wrong here. — Preceding unsigned comment added by 31.32.40.68 (talk) 09:30, 20 May 2012 (UTC)

It has, due to vandalism. I have undone it. Peter M. Brown (talk) 13:38, 20 May 2012 (UTC)

Non-synapsid synapsids?

I'm a bit curious about a recent edit. It says: While both branches began with the original anapsid-type skulls, they both independently evolved various configurations of multiple additional skull openings. If I remember correctly, there are anapsid Eureptiles, but do we have any synapsid critters (really, undoubtly synapsid) with no temporal opening? While it stands to reason that it well could have been such beasts, do we have the critter? If not, I strongly suggest we retain the original wording. It was less specific, but had the advantage of catering both ways of classifying. Petter Bøckman (talk) 20:49, 20 December 2011 (UTC)

I could have sworn I recalled some basal synapsids with anapsid skulls but I could be mistaken. Best revise it until I can dig something up. The most derived non-amniote reptiliomorphs were anapsid, right? Or is the anapsid skull a derived trait re-evolved in true reptiles?MMartyniuk (talk) 14:00, 21 December 2011 (UTC)

I'll look into the synapsid thing too, and see if I can come up with something. If I remember correctly, there's some very badly crushed skull about somewhere, with questionable reconstruction.

You are right about the early reptiles, critters like Hylonomus had inherited a skull that would look equally much at home in any of the small, advanced reptilimoprphans. The only trait to disappear in the transition was the pronounced otic notch found in labyrinthodnonts, but non in reptiles. Some of the critters suggested as ancestors of amniotes or early amniotes like Casineria, Westlothiana and Solenodonsaurus have them greatly reduced or lacking all together. Petter Bøckman (talk) 19:14, 21 December 2011 (UTC)

Edit: I have made a provisionary version of the first section (Anapsid, Diapsid etc), please improve it! As for the use of "Anapsida" as a name for a coherent, though paraphyletic, group, it is what everyone from Romer to Modesto and Anderson (the latter are hard core PhyloCode fans) call them, so I suppose it is OK to use like I have. The term "true reptiles" is a bit unfortunate, as it could be taken to mean Eureptilia, we might want to find a better term. Then again, when we come down to details like the composition of Eureptilia, the tree isn't really all that stable, I think we are better served by sticking to the larger picture. Petter Bøckman (talk) 19:53, 21 December 2011 (UTC)

Isn't Synapsida defined by the synapsid skull? The oldest synapsids like Archaeothyris have these skull openings. That means anything without a synapsid skull isn't a synapsid. Either the ancestor of synapsids and sauropsids had an anapsid skull, or it had a synapsid skull and sauropsids became secondarily anapsid. I've never heard anything about this second possibility. Maybe its best to say: While both branches descended from a common ancestor with the original anapsid-type skulls, they both independently evolved various configurations of multiple additional skull openings. Smokeybjb (talk) 17:09, 25 December 2011 (UTC)

This is the old classification debate again, though with a twist. If you define synapsids as you have done (and it certainly is the original and a well used definition), then all synapsids have the synapsid fenestra. This is however a Linnaean (or traditional) definition. If you on the other hand prefer phylogenetic nomenclature and use a stem-based definition (I believe this is the most common phylogenetic definition for synapsids, going back to Goodrich), then MMartyniuks edit may be quite accurate. However, there's a twist here: We do not know exactly how the split happened, who the last common ancestor was, but it is not a far fetched assumption that the last common ancestor was an anapsid. Thus, the evolution of the synapsid fenestra would have happened in the stem. It is on the other hand also possible that the last common ancestor had evolved a thinning of the skull roof to give room for the chewing muscles, and that the fenestra run all the way to the bottom of the stem. There's simply not (presently) any fossils to allow us to tell for sure. This is why I suggest sticking to the bigger picture and not get our nose bogged down details just here. The synapsid article is possibly a better place for such an argument. Petter Bøckman (talk) 21:53, 25 December 2011 (UTC)

I hadn't thought about it being a stem-based taxon, but I agree, this is something for the synapsid or possibly amniote article (since Amniota is synapsids + reptiles in phylogenetic terms). Smokeybjb (talk) 03:47, 26 December 2011 (UTC)

Behavioural topics

I notice that after extensive and interesting treatments of classification, history, and anatomy, there follows one section about repltile behaviours, i.e. "Defense mechanisms". I think this seems odd: why select out defensive behaviours as the ones which need to be described rather than e.g. courting/ mating/ pair-bonding, or hunting and eating, etc.? Maybe a broader view of behaviour might be a good plan? Best wishes, Richard 82.19.24.148 (talk) 23:34, 9 January 2012 (UTC)

This is a good idea, the question is only what we should put in there. I suppose a bit about hunting (most reptiles are carnivores) and perhaps mating games? Petter Bøckman (talk) 12:17, 10 January 2012 (UTC)

"Common" definition of reptiles?

A recent edit questioned the common definition of "Reptile" by adding a "whom?"-template. It's kind of hard to prove what's "common", particularly as those interested in getting definitions in print are those that want a new definition known. I have found this back-up of this articles statement from The free Dictionary:

reptile, name for the dry-skinned, usually scaly, cold-blooded vertebrates (see Chordata) of the order Reptilia. Reptiles are found in ... (snipp)

Evolution Reptiles first evolved from amphibians about 250 million years ago in the Carboniferous period and were dominant in the world's fauna during the Mesozoic era, sometimes called the Age of Reptiles. The dinosaurs, the marine ichthyosaurus and plesiosaurus, and the flying pterosaurs reached the peak of their development and distribution in the later part of this era (late Cretaceous period). Mammallike reptiles appeared very early in reptilian history and by the Triassic period had given rise to mammals. Bird ancestors arose from precursors of the dinosaurs; the first known birds lived in the Jurassic. The only reptiles that survived into the Cenozoic era belonged to the presently living orders. The approximately 6,000 living reptile species represent a very small fraction of this once vast class.

Bibliography

See R. Conant, Field Guide to Reptiles and Amphibians (1958); A. Bellairs, The Life of Reptiles (2 vol., 1970); K. P. Schmidt and R. F. Inger, Living Reptiles of the World (1957, repr. 1972); H. M. Smith and E. Brodie, Reptiles of North America (1982); H. M. Smith and H. S. Zim, Reptiles and Amphibians (1987).

This is a common encylopedia, not a specialist work, so I suppose any definition herein would be "common". The "Evolution" section details more or less the same groups mentioned in this article. It also coincides with the groups that are indicated by the quote from Colin Tudge in the WP article. The Encylopedi Britannica on the other hand seems to use Benton's Saurapsida-sans-birds definition. The Palaeos' page on the term supports the Free Dictionary and Colin Tudge as to what is the "common understanding". I personally quite like Palaeos, but are they a suitable source for what's "common"? Petter Bøckman (talk) 20:56, 23 March 2012 (UTC)

I think that either the definition in the Free Dictionary or that in in the Encyclopædia Britannica would do just fine. In each case, the first sentence is the proposed definition; the rest of the entry, listing sample reptiles, is elaboration, not definition. The "common definition" in WP, in contrast, starts out with a list of taxa—not the common understanding or the common definition. Further, the so-called common definition includes the amphisbaenians, not mentioned in either source, and excludes the caimans; anyone who has ever met one would call it a reptile. The more appropriate trait-based definitions of the Free Dictionary and the Britannica can accommodate both the caimans and the amphisbaenians with no difficulty.

I recognize that one must exercise restraint in challenging claims to the effect that views are "common." Sometimes, these claims can be valuable but hard to source. In this case, though, I think the challenge appropriate.

Peter M. Brown (talk) 22:13, 23 March 2012 (UTC)

If I have understood your edits right, the sticky point here is whether it is "common" to include the mammal-like reptiles in (Class) Reptilia. I would think this is the common approach for the Class. Benton is the only one using a class with a different content, but then again he don't call it Reptilia. In most of his more general articles, he uses "reptile" in the traditional sense.

Don't get me wrong, I have nothing against being challenged here. One should always strive to back up ons claims. Would it be appropriate to rather repeat the trait based definition (any of the old authorities from Huxley to Colbert, heck, even Benton would do), and then list a few of the groups?Petter Bøckman (talk) 22:25, 23 March 2012 (UTC)

The substantive contention of the second half of the paragraph is that the meaning of the term has continued unchanged from the late 19th century. That is simply incorrect or, at best, inadmissible POV. Not only the two sources you cite but also the Merriam-Webster, Collins, and American Heritage dictionaries take the presence of scales or scutes as a defining characteristic, strong evidence that this trait is part of the contemporary meaning. Well into the 20th century, however, reptiles were taken to include nonmammalian therapsids, which didn't have this integument. The meaning has changed and the paragraph is factually incorrect.

The section is devoted to the history of the concept. It needs to end with a sentence or two bringing the account up to the present, or nearly so. We could replace the final two sentences of its last paragraph, therefore, with something like the following:

In the 20th century, many writers have not included the nonmammalian synapsids in the reptiles, though some still refer to them as "mammal-like reptiles".

What do you think?

Peter M. Brown (talk) 23:59, 23 March 2012 (UTC)

A couple of points:

We do not know that Therapsids did not have scutes. Considering some modern mammals do have them (beavers tail, opossum feet etc), it stands to reason that at least the exposed parts of therapsids had them too. We know fur is out of the question for al but the most advanced, small therapsids. The problem here is that we are trying to imagine how we might have placed an animal like Gorgonops, when the salient feature (scutes) are unknown to us. Thus we are left with the how authorities of the past have classified them.

And yes, the composition of class Reptilia really was extremely stable until a few years ago. Huxley, Owen, Haeckel etc lumped the therapsids in with the reptiles, a tradition continued by Romer, Colbert etc well into the 1990s. The cut-off points to birds and mammals were well understood and defined. Heck, I even have a 2001 book following this system (Hildebrand, M. & G. E. Goslow (2001): Analysis of vertebrate structure. New York: Wiley. p. 429. ISBN 0471295051.). The authors who argues for splitting up the reptilian tree usually used the term Sauropsida for the modern reptiles (with or without birds), so that the meaning of Reptilia remained unaffected, see Benton for an example. So yes, I stand by my word: The composition of Class Reptilia remained virtually unchanged for more than 100 years, the only real change being in the understanding of "Cotylosaurs".

I realize we are all coloured by what we have been taught. Benton's work is extremely influential, but I think it will take some years yet until his use of Synapsida as a separate class filters into the population at large. Petter Bøckman (talk) 20:44, 24 March 2012 (UTC)

Points granted. Do you want to "repeat the trait based definition (any of the old authorities from Huxley to Colbert, heck, even Benton would do)"? I don't think a list of groups is necessary here; there are lists elsewhere in the article.

I didn't know about beaver and opossum scutes. The Opossum article does mention them but gives no sources. Would you provide some? Thanks.

Peter M. Brown (talk) 00:21, 25 March 2012 (UTC)

Actually, I've been looking for a source on the opossum scutes myself. It seems no-one have given them much mind. It is perhaps a bit like finding an article saying an adder lacks legs, they just do. Here's a picture though.

I'm not really sure what I want to do with the "common understanding"-bit. I think Colin Tudge's definition seems spot on (all amnitotes that are neither birds, nor mammals). Perhaps we could use that one, and mention the scales/scutes as a commonly associated trait? Petter Bøckman (talk) 07:49, 25 March 2012 (UTC)

How about:

In the late 19th century, a number of definitions were offered. The traits listed by Lydekker (1896), for example, include a single occipital condyle, a jaw joint formed by the quadrate and articular bones, and certain characteristics of the vertebrae. The animals singled out by these formulations, the amniotes other than the mammals and the birds, are still those considered reptiles today.

Would this work?

Peter M. Brown (talk) 19:07, 25 March 2012 (UTC)

Splendidly! Petter Bøckman (talk) 19:16, 25 March 2012 (UTC)

Some v more v most

This edit is pretty rude and uncivil, but I actually could care less about the word. I think a guidelines is that original content stays until there's some evidence or support for a change. I did a quick google and PubMed search, and most articles are written with respect to herpetology using caldistics rather than the older binomial. I'm not sure whether there is a way to establish what is consensus these days, but my observation is that "most" use cladistics. Otherwise, we should stick with what was written. I just don't think rudeness should be the norm around here on a genuinely disputed point. SkepticalRaptor (talk) 22:38, 24 March 2012 (UTC)

Good heavens! I certainly didn't intend to be rude. My point was only that I thought changing the word would be an improvement. Your point about the guidelines is well taken, though, and I will certainly respect them. My mention of Mustela nivalis was intended to inject some humor, which I thought would be welcome. Peter M. Brown (talk) 23:46, 24 March 2012 (UTC)

Just a point to SkepticalRaptor: Binominal really refer to the two part name (genus-species) of species, which as far as I know is still near universal. Cladistics is a method, not a classification system, and is also near universal. The classification systems are properly Linnaean classification (ranked) or phylogenetic classification (unranked). Petter Bøckman (talk) 18:54, 25 March 2012 (UTC)

Drawing

I found this image, File:Gallotia simonyi-female.norarte.jpg on WC. I love scientific illustrations, and feel they convey information in a way highly complementary to photos. Anyone else find this image appropriate for the main article? i dont usually edit the high profile articles, so i am asking first. ps a juvenile image is also available.Mercurywoodrose (talk) 02:48, 7 April 2012 (UTC)

Only if the image clarifies or illustrates material in the text! See my discussion of the use of images in the Mammal article. Several images in the latter fail this test, and I shall delete them if there is no objection by 17:00 today (though File:TheCheethcat.jpg is a very nice piece of animal photography). Only MMartyniuk has reacted, and he concurs. In my discussion, I hold up the Reptile article as an excellent example of how things should be done; do not mar the article with clutter, whatever value it may have in isolation.

The image is already used at Technical illustration, where it does augment the text. It could be added to Reptile as an example of an omnivorous reptile, but the there is hardly more room in Reptile#Digestion. The image's intrinsic value as a scientific illustration is not sufficient warrant for its inclusion.

Thank you for asking. There is certainly a place for editing boldly, but there is also value in sounding out the community first.

Peter M. Brown (talk) 13:09, 7 April 2012 (UTC)

Definition

There are warm blooded fossil reptiles and there are fossil amphibians with scales, so reptiles should be defined as they are classically, as scaled animals with hard shells when the have eggs (which excludes amphibians) and which lack hair and feathers. μηδείς (talk) 21:55, 6 June 2012 (UTC)

What do you mean by "classically"? Is Cuvier's work "classical"? He included amphibians as "reptiles". Peter M. Brown (talk) 22:09, 6 June 2012 (UTC)

Also, by "scaled animals with hard shells when the have eggs" do you mean "scaled animals that produce eggs with hard shells when they do produce eggs"? If so, how does that exclude the hammerhead shark, which (like some skinks) is scaled and viviparous? Peter M. Brown (talk) 22:42, 6 June 2012 (UTC)

The amniote egg is typically described as hard shelled. If you want to use other terminology I don't have a problem. You can also use a different word from classical if you like but it not even in the lead, just my comments. In each case it is a matter of distinction, from the shelllless eggs of modern amphibians and the cladistic views of modern taxonomists.μηδείς (talk) 23:02, 6 June 2012 (UTC)

Sharks are not amniotes and modern amphibian eggs don't have shells so I have taken out hard-shelld which is not technical to avoid problems with people saying some reptiles lay softer shelled eggs. μηδείς (talk) 23:09, 6 June 2012 (UTC)

I'm not objecting to the word "classical". I'm asking what you mean by it. Substituting a different word isn't going to answer the question. A "classical" definition (or "canonical", or whatever) is presumably one that was, at some point, offered by someone influential and widely accepted. Who? Owen? Or am I totally misunderstanding you? Peter M. Brown (talk) 23:39, 6 June 2012 (UTC)

I used the term classical definition in my comment to distinguish from cladistic definition, not to specify any authority, especially not a 19th century one, although I assume it would have been Romer had I named one. I happen to be an Ernst Mayr man myself so far as classification. Before I read Hennig in university, and learned about cladistics, reptiles were defined as animals with eggs with shells that lacked hair and feathers and happened to be scaly and cold-blooded. Cold blooded and scaly were obviously not defining characteristics per se, since they applied to fish and early amphibians and we know some dinosaurs at least were endothermic. If we take living reptile to mean chelonia-lepidosauria-crocodilia then the (primitively) shelled eggs but without (flight) feathers and hair definition is the most parsimonious and doesn't run into problems by excluding non-avian dinosaurs. μηδείς (talk) 00:21, 7 June 2012 (UTC)

Obviously we will have to revisit this when they discover Dimetrodon had hair. μηδείς (talk) 00:24, 7 June 2012 (UTC)

I have no problem with deleting the reference to scales per se, but we should then at least explain amniotes in some way for the lay reader to understand, otherwise we might as well be talking about apterous bipeds. Do you have any suggestions? μηδείς (talk) 03:35, 7 June 2012 (UTC)

The problem here is we are dealing with several ways of dealing with classification, some based on traits and some on phylogeny (yes, defining grades phylogentically is quite possible). Egg with shells and scales are very much parts of the trait based and common understanding of the term reptiles, see The free Dictionary and the Palaeos' page on the term. What is usually forgotten when we are dealing with this kind of definition, is that it is mixed in with an evolutionary understanding, so that animals who hails from ancestors who had these traits are still reptiles, just like caecilians and snakes are still tetrapods, despite lacking legs. The "classical" evolutionary taxonomy definition (Romer/Colbert/Carroll etc) is Reptilia = all animals with an amnion that are neither birds, nor mammals. In PhyloCode parlance I suppose you can say it would correspond to Casineria + Lacerta - (Morganucodon + Homo) and - (Archaeopteryx + Passer). Thus the hair on pterosaurs or feathers on Sinosauropteryx does not stop them from being reptiles. As for scales on the synapsids, I'll just leave you with this picture of a primitive extant mammal.

I suggest keeping the eggs and the scales in the lede. It more or less define the modern groups, and the details of these traits in the extinct groups can be covered in the main text. Petter Bøckman (talk) 07:02, 7 June 2012 (UTC)

Petter, you say above: "I think Colin Tudge's definition seems spot on (all amniotes that are neither birds, nor mammals). Perhaps we could use that one, and mention the scales/scutes as a commonly associated trait?" I have implemented the first part of your suggestion. The second part may need some work. The the eggs also need to be mentioned as a commonly associated trait. Peter M. Brown (talk) 14:38, 7 June 2012 (UTC)

As far as eggs go: Neither Dictionary.com nor Merriam-Webster even mentions eggs in defining "reptile". The Palaeos definition, 68 words long with six parenthetical phrases, is surely too specific. The entry in The Free Dictionary is more encyclopedic than lexicographic, providing information about the subject as well as its meaning; it doesn't get around to mentioning eggs until the third paragraph and notes, in that paragraph, that some reptiles are viviparous. I suggest that the eggs are not an important part of the common understanding. For what it's worth, I also note that both The Free Dictionary and Dictionary.com include "cold-blooded" as a defining characteristic. Peter M. Brown (talk) 15:22, 7 June 2012 (UTC)

I think the definition with the eggs was spot on as it was. Basically, a "shelled egg" means the same as an amniote egg, sharks notwithstanding. If anyone think people are likely to confuse sharks with reptiles, we could always ad the caveat "land living" or "land-living vertebrates". The term amniote as used by Tudge is of course the correct one, but it is a rather technical term not likely to be understood by the non-expert reader, thus I would like to avoid it in the first sentence of the lede. By using shelled egg (=amniote) and scales (=not a pelage or full or a full feather habit) we are typically expressing in lay-mans terms whet Tudge is saying. If the problem is that such a definition is too fussy, we could ad a chapter on the typical traits right below the lede, perhaps based on what is already in the article. There we can discuss fuzzy pterosaurs and and the question of the skin of mammal-like reptiles to our hearts content.Petter Bøckman (talk) 16:15, 7 June 2012 (UTC)

I think this version:

Traditionally, Reptiles are members of the vertebrate class Reptilia comprising the amniotes that are neither mammals nor birds.

of the first sentence is excellent. I again do wish there were a quick way to explain amniote for lay readers. I am going to add that living reptiles can be described as cold-blooded tertrapods with scales. If anyone strongfly objects they can remove it, but I think it will be clear to lay readers. μηδείς (talk) 17:29, 7 June 2012 (UTC)

How is this for a quick way?

Traditionally, Reptiles are vertebrates in the class Reptilia comprising the amniotes—land animals whose eggs are fertilized within the mother's body—other than mammals and birds.

And do we really want to say that extant reptiles are cold-blooded? What about the endothermy of brooding pythons? (See abstract here).

Peter M. Brown (talk) 17:59, 7 June 2012 (UTC)

Ectothermy is on a relative scale, so I think we are safe with the distinction. That's a great suggestion on amniotes. μηδείς (talk) 18:06, 7 June 2012 (UTC)

I would go with shelled eggs. Internal fertilization is not at all exclusive to amniotes (a number of amphibians do it as well). Petter Bøckman (talk) 18:21, 7 June 2012 (UTC)

That's no better. Nearly half of the skink species are viviparous. Peter M. Brown (talk) 19:02, 7 June 2012 (UTC)

We aren't defining the group based on internal fertilization, but as amniotes, and then simply hinting to laymen in an aside part of what being an amniote is about. It's offered as a parenthetical remark to the definition, not part of the definition. (Philosophically speaking, the definition's genus is amniote and its differentia is that is not a bird or a mammal. See genus–differentia definition.) We couldn't omit amniote and let internal fertilization stand in its place, but we aren't doing that. As it stands, the definition is technically correct and about as concise without being vague as I think we are going to get it. μηδείς (talk) 19:48, 7 June 2012 (UTC)

If I were to nitpick, I'd say they are mostly ovoviviparious rather than viviparious, but there are true viviparious reptiles so your point stands. Again the argument is in the logic of "primitively". If some member of a group have evolved a divergent trait, it's not a problem. If the traits defining a group (in this case the amniotic egg) is found in the ancestral groups (amphibians in this case), it's a bit different. We really need to put the amniotic egg in there, but I would like to avoid the terms "amniotic", "amnion" or "amniote" in the first sentence.

Edit: I like the "membrane-protected" edit, neat solution! Petter Bøckman (talk) 20:12, 7 June 2012 (UTC)

(edit conflict) [I looked at the amniote article for hints and added "membrane-protected" which is a very simple way of referencing the essence of amniote versus non-amniote.] Yes, I think the intro is a huge improvement all around since a week ago. μηδείς (talk) 20:15, 7 June 2012 (UTC)

I restored the "birds and mammals" section to a parenthetical comment rather than a separate paragraph after the "aves" sentence since it explains why the separation was historically made. I agree with separating out the "reptiles originated" paragraph and had intended to make that edit myself.μηδείς (talk) 20:42, 7 June 2012 (UTC)

I simplified a bit, birds were mentioned twice. Petter Bøckman (talk) 21:19, 7 June 2012 (UTC)

Isn't the fact that the entire amniote egg is protected by a membrane a bit trivial? Yes, the outer jelly of the amphibian egg is not so protected, but—beneath the jelly—the embryo and perivitelline space are shielded by the vitelline membrane. Peter M. Brown (talk) 16:55, 14 August 2012 (UTC)

I don't think we loose anything by loosing the word "entire", except the word of course. Petter Bøckman (talk) 18:18, 14 August 2012 (UTC)

The word "entire" is mine. That's not my point. The article characterizes amniotes as "air-breathing vertebrates whose membrane-protected eggs are fertilized within the mother's body". Caecilians aren't amniotes, but they are air-breathing vertebrates whose eggs are fertilized within the mother's body. Aren't the important parts of the caecilian egg protected by a vitelline membrane? If so, the characterization of amniotes is defective. Peter M. Brown (talk) 19:03, 14 August 2012 (UTC)

The amnion needs to be put in there somehow. What about "protected by a double membrane called the amnion, allowing the egg to breath effectively on land", or would that be too long? Petter Bøckman (talk) 22:20, 14 August 2012 (UTC)

Well, at least it's accurate. Maybe someone can come up with a better wording. Peter M. Brown (talk) 18:22, 28 August 2012 (UTC)

On second thought, therian mammals don't have an egg (excluding the female gamete, of course). Peter M. Brown (talk) 17:10, 29 August 2012 (UTC)

scales and egglaying do not define reptilia

Why, Peter, are you edit warring with me over this? Either just birds being excluded should be mentioned or the more full explanation that neither scales, egglaying nor warmbloodedness can define retilia as a whole should be given. I see no reason why the fuller summary should be omitted from the paragraph. Please restore the material rather than edit warring to delete it. μηδείς (talk) 23:09, 7 June 2012 (UTC)

Hey, gimme a chance! I took a break for dinner. I'm now back to working on it, taking your comments seriously. Peter M. Brown (talk) 00:02, 8 June 2012 (UTC)

Okay. I am. If it really bothers you, we can pare down the sentence just to explain that birds alone are not included except by cladists. then reference to mammals should be left out. Then there should be a separate section explaining the historical evolution of the classification. But since the topics are related I felt the one section with the words scales eggs wrmblooded and historically was sufficient. we could also and probably should add a sentence on how skull shape has historically been an issue. I had considered separating the four bulleted groups into anaspids and diaspids, lepidosaurs and archosaurs, but felt it too cluttered. μηδείς (talk) 00:19, 8 June 2012 (UTC)

OK, here's what I propose for the paragraph.

Although they have scutes on their feet and lay eggs, birds have historically been excluded from the reptiles, in part because they are warm-blooded. They therefore do not appear on the list above. However, as some reptiles are more closely related to birds than they are to other reptiles—crocodiles are more closely related to birds than they are to lizards—cladistic writers who prefer a more unified (monophyletic) grouping sometimes also include the birds: over 10,000 species, see Sauropsida.

For your convenience, I have set up a comparison here between your most recent version and the above, using my sandbox. I mention scutes instead of scales, but I do refer to eggs, warmbloodedness, and history. I have restored mention of the reptile group list, which is what I originally wrote the paragraph to discuss. I have dropped mammals and dinosaurs. Most importantly, the new text from "However" to the following dash should make clearer just why it is a consequence of the relationships between crocodiles, birds, and lizards that the inclusion of birds among the reptiles renders the latter a more unified group. This was admittedly hard to follow, and the dinosaurs made it even harder.

Any suggestions or objections? or shall I go ahead with this version?

Peter M. Brown (talk) 00:57, 8 June 2012 (UTC)

I think that's very good and have instituted it with the change of the colon to a preposition. I do think we should insert two or three sentences to summarize the sections on skulls and classification in the 20th century either before "see Sauropsida" or as a paragraph after it:

With the discovery of a great diversity of fossil reptilians, 20th century paleontologists rationalized their classification according to the presence and structure of skull openings to accommodate jaw muscle attachments. Among other groups, turtles and primitive forms were grouped as anapsids; the reptilian ancestors of mammals as synapsids; and most of the rest including lepidosaurs and archosaurs as diapsids. The most radical reclassification of all does away with reptiles in the traditional sense and splits all amniotes into those most closely related to mammals, the Theropsida, and the rest of the reptiles including birds as Sauropsida.

μηδείς (talk) 01:54, 8 June 2012 (UTC)

I see a few problems with your proposal.

• You need a secondary source to make a generalization about "20th century paleontologists". Perhaps you have one in mind.

• A classification based on temporal fenestrae will have to include the Euryapsida. In fact, these animals are nowadays classified as diapsids, but this practice is based on other features. Temporal fenestrae are not the basis for classification.

• The term primitive is best avoided.

• The term "anapsid" is seldom used nowadays; only 440 hits on Google Scholar. Modesto and Anderson (2004) recommend "that Anapsida [be] abandoned as a formal name in light of its long precladistic usage as the name of a paraphyletic group of amniotes."

• Many sources, including the Synapsida article, do not restrict the term "synapsid" to mammalian ancestors but apply it to the mammals as well.

• You need a source for "the most radical reclassification of all". The manner of presentation suggests that it is more radical than the classification mentioned in the previous sentence, though it seems compatible with them.

I hope that this is helpful.

Peter M. Brown (talk) 19:04, 8 June 2012 (UTC)

Thanks. I am not sure why I would need a new source to summarize the material in the article about 20C biologists such as Romer. Maybe you are uncomfortable with the word paleontologist? Can you clarify? I left Euryapsids out intentionally but referred to them obliquely by saying "among other groups." They could be put back in, but I was trying not to get too technical, just introduce the idea. On the other hand, I felt anapsids were important enough to pre-cladistic thought to retain, since he point of the lead is not to summarize only current thinking but rather the contents of the article. The same with synapsid-_the idea was to summarize the section, not to present only the most recent usage. We could add a mention of mammals, but like euryapsid, that is handled in the main text. As for the use of the word radical, it is used in the sense of making the most fundamental distinction, not in some political sense. Dividing the amniotes in two at the root is making a radical distinction. If you prefer some other word we can find a synonym. As for "primitive", we could use "fossil", I was just trying to avoid redundancy, but I agree many anapsids were highly derived anatomically. μηδείς (talk) 21:41, 8 June 2012 (UTC)

I can respond in detail, and will if you think it useful, but I do wonder about appropriateness. This is a lead and, according to WP:LEAD, "should briefly summarize the most important points covered in an article". How briefly? As it stands, the lead is about 7% the length of the text following the lead, not counting references. Your proposed summary of Skull openings in 20th-century classification is about 40% the length of the subsection it purports to summarize. I suggest that 40% is too large.

It is a deficiency of the current lead that it fails to reflect the historical information in the article. A summary of this part is needed. The entire History of classification section, however, could be summarized with a brief paragraph such as:

Traditionally, the reptiles were one of the three classes into which the amniotes were divided, the others being the mammals and the birds. By the middle of the 20th century, it had become more common to split the amniotes into four groups based the number and position of temporal fenestrae, openings in the side of the skull. Each of the four groups included some extinct reptiles. More recently, taxonomists have preferred to group animals based on shared ancestry rather than on shared features; this approach has led some to define the reptiles in a manner that includes birds.

This is about the same length as your proposed text but, as it summarizes the entire section rather than just a subsection, it is only about 9% of the length. Since it has a narrative structure, it is relatively easy to read, another feature that is desirable in the lead.

Peter M. Brown (talk) 15:09, 9 June 2012 (UTC)

I like your summary Peter, only I would use "traditionally, the reptiles are one of three classes...". The class Reptilia still see quite a bit of use, particularly in general zoology. Petter Bøckman (talk) 19:09, 9 June 2012 (UTC)

That reads nicely, but you have omitted the reason for the new classification--the fossil discoveries--and have avoided mentioning all of the central concepts while linking only to the very derived concept of temporal fenestrae. Also, the definition of reptiles which includes birds also omits the synapsid reptiles, which you do not mention. Expanding your suggestion to retain the essantial concepts:

Traditionally, the amniotes were divided into reptiles, mammals, and birds. With the discovery of a great diversity of fossil reptilians, it became more common by the mid-20th century to group them according to their skull openings. Turtles and some extinct forms were grouped as anapsids; mammals and their ancestors as synapsids; ichthyosaurs and other aquatic forms as euryapsids: and the rest, including lepidosaurs and archosaurs as diapsids. More recently, cladists have preferred to group animals by ancestry rather than features; this has led some to split mammals and their ancestors into the Theropsida and to redifine the rest of the reptiles, including the birds, as Sauropsida.

This might be pared down further but the linked concepts should be retained.μηδείς (talk) 22:28, 9 June 2012 (UTC)

Have I misunderstood the project? I took it that we want to summarize some or all of the History of classification section. But the only reference to fossils in that section deals with the incorporation of dinosaurs and therapsids in Reptilia by Owen and Huxley, long before the mid-20th century. And introducing the four -apsid terms in the lead when they have not been previously defined is surely to make things unacceptably difficult for the general reader. Are we, indeed, discussing the lead? We can usefully note there that there was a fourfold division based on skeletal characteristics, but the details are best left for the main text. By the way, my omission of the fact that cladists who include the birds in Reptilia also exclude the synapsid reptiles was quite deliberate. Perhaps the Phylogenetics and modern definition subsection should mention the fact; it doesn't, though, and neither should the summary.

I suggest that we wait for tomorrow, hoping that Petter Bøckman has something to add. He almost never contributes this late in Norway's night.

Peter M. Brown (talk) 23:51, 9 June 2012 (UTC)

Sory Gents, been away all day. Will write something intelligent tomorrow. Petter Bøckman (talk) 19:57, 10 June 2012 (UTC)

The purpose of the lead is to summarize all the essential points of the main article and to serve essentially as a mini-article. All of the linked concepts I have provided are mentioned in the classification section and its history subsection--I did not mean to mislead you, Peter, into thinking I was offering a summary of a subsection of that subsection. (I am bemused that you would object to "with the discovery of a great diversity of fossils" not based on its being inessential, false or unclear, but because it is in the immediately previous subsection.) A person reading the summary of this article should see all the main themes and concepts that it will treat.

Your proposed summary is 86% as long as mine but mentions only one concept--temporal fenestrae, omitting the explanation of my original proposal that they "accommodate jaw muscle attachments"--while mine introduces some ten or so concepts not yet mentioned in the lead. Of course the lead does not give the technical definitions of such things as diapsids up front in full, but the reader will certainly understand these are groupings based on skull structure and will read the appropriate article section if he is interested. Kind of like a "concepts we will learn in this chapter" introduction in a textbook. If some points could be further expanded or claarified in the text that is a separate issue. The article's lead is very short for its overall length. We need to cover these ideas without objecting that points in the summary are treated somewhat independently of the order in which they are found in the text. If you still have objections not dealing with which section is being summarized, perhaps you can do as I have done and rewrite my last suggestion, omitting maybe eurypsids like I did in my first proposal and restoring the jaw muscle attachments explanation if you think that would be more economical and clearer to readers? Perhaps lepidosaurs and archosaurs could be briefly delineated. The section should also be integrated with or used to replace the current mention of Sauropsida in the lead. That would focus on working on the summarization rather than on objections about the state of the text or its order of presentation. μηδείς (talk) 20:34, 10 June 2012 (UTC)

We don't seem to be coming to any agreement. Do we need an RFC on this? I hope that Petter can help.

I don't agree with your emphasis on "linked concepts". All the concepts in a lead should be used in a manner that reflects their use in the main text, not just the linked ones. This includes "fossil", which you did not link but could have. I repeat: fossils are treated only once in the entire classification section, in connection with 19th century taxonomy; they are never presented as relevant to the fourfold division of amniotes into the -apsid groups. In the entire article, the term "fossil" only occurs twice more, once in a discussion of Carboniferous footprints and once in considering gastroliths; never with any connection to jaws, fenestrae, or anything else cephalic. If you want such a connection in the lead, you have to add it to the main text as well.

It is quite appropriate for a textbook to have a "concepts we will learn in this chapter" section. It is not appropriate in Wikipedia. According to WP:LEAD, "The lead should be able to stand alone as a concise overview"; the reader should not have to cope with terms that require reading beyond the lead itself, although one does write the lead with the hope that the reader will read more. WP:LEAD also says, "Where uncommon terms are essential, they should be placed in context, linked and briefly defined". (Emphasis added.) You can't get away with an unfamiliar term just by including a link .

I quite agree that points in the summary may be treated somewhat independently of the order in which they are found in the text. I also agree that it is better simply to write of "skull openings" rather than introducing "temporal fenestrae" and then needing to explain the term. Whether "skull openings" is linked is entirely optional; linking is only important, again per WP:LEAD, when terms are uncommon.

Peter M. Brown (talk) 21:52, 10 June 2012 (UTC)

The problem we are facing here is that the classification section is bloated well beyond what is needed and dominates the article unduly. It takes up a lot of space, compared to the sections on anatomy and behaviour. The reason for this is of course that the very term "reptile" is the ground zero of the traditional/phylogenetic classification debate, and everyone want their say. Would it perhaps be an idea to just put a summary under the history of classification, and make a separate article for the whole debacle? That way we don't need to clog up the lede with all kinds of classification details, details which I believe are of limited interest to the casual reader. Petter Bøckman (talk) 08:28, 11 June 2012 (UTC)

A separate article would require a lead. If we simply transplanted the Classification section to a new article, μηδείς and I would still be disagreeing about (1) whether the importance of fossil discoveries to 20th-century classification can be mentioned in the lead but not in the main text and (2) whether a "concepts we will learn in this chapter" approach is acceptable in a Wikipedia lead. If the material were moved to a new article, though, it could be expanded further. μηδείς, are you willing to add new historical material explaining in some detail how fossil discoveries led to the fourfold division of the amniotes? I could then have no objection to the mention of fossils in the lead. Further, since this classification would then figure prominently in the new article, would you be willing to forgo using undefined terms in the lead? Peter M. Brown (talk) 14:35, 11 June 2012 (UTC)

As there has been no further discussion, I have added a relevant paragraph to the lead. See my comments below. Peter M. Brown (talk) 00:55, 14 June 2012 (UTC)

Image

I love Petter's image for the article. I was working on an image for the article myself before he posted his. See my incomplete list of candidate images here and those completed composites I have uploaded on the top of my talk page here. I do want to add some more diversity, and was thinking of creating a new one based on his but adding at least a snake and another lizard, especially the mole lizard or a chameleon. I know it's a lot of work to create an image, so I don't want to propose a new one without input, especially from Petter. First, would anyone like to suggest an snake images? I am particular to the eyelash viper. Second, should I limit myself to living reptiles, or add some fossil forms? Any comments will be appreciated. μηδείς (talk) 02:33, 8 June 2012 (UTC)

File:National Aquarium.Australia.Pignose.turtle.jpg

Good idea! While I went for feature pictures as basis, not all are suited for a collage like this, and the picture can always be improved. As you suggested, a picture of an extinct animal (a dinosaur perhaps?) could be nice, but we need one that looks good with the other pictures (there are aesthetical as well as pedagogical issues here). There are more nice pictures in the 2011 Picture of the Year on Wikimedia. My personal favourite for another snake would be this:

Persoanlly, I would leave extinct reptiles (at least extinct avemetatarsalians) out of the lead image and intro entirely. After a long discussion over introducing the concept on the basis of traditional characters and definitions, do we really want to confuse things by including the skeleton of a warm-blooded egg-laying feathered animal? Under the (reasonable) paraphyletic definition agreed upon above, many if not all dinosaurs would not be considered reptiles. MMartyniuk (talk) 14:09, 8 June 2012 (UTC)

We certainly will avoid a whole can of worms by leaving out extinct forms, as well as avoiding having pictures that look out of place with the others. Petter Bøckman (talk) 22:47, 8 June 2012 (UTC)

Yes, I agree with the consensus. First, the focus should be on taxonomic and physiological diversity. Second, aesthetics are important, and we should make sure the chosen forms are attractive if possible, clearly visible, and well-framed. And I agree fossil forms are a bad idea. μηδείς (talk) 00:07, 9 June 2012 (UTC)

New paragraph in the lead

The lead has needed a few sentences to summarize the History of classification subsection. There has been some controversy as to how to go about this. I am adding a new paragraph to provide the summary, bearing in mind the following:

• The information conveyed in the lead should be limited to what is contained in the main text.
• The lead should not use technical terms without providing a brief definition.

Both of these principles derive directly from WP:LEAD. An additional constraint, which seems to me reasonable, is:

• A paragraph in the lead devoted to summarization should be no more than 5% the length of the text summarized.

I am sure that others can improve on my wording. It would be helpful, though, if any proposed enhancement that conflicts with these three principles be discussed here first.

Peter M. Brown (talk) 00:46, 14 June 2012 (UTC)

Sorry, been busy for a while.

You have done a good job of summarize the subsection, but I have rewritten the section a bit. It is not as if the threefold classification of amniotes is exclusively something of the past, thus I changed it to "are traditionally" to reflect current use. The temporal fenestrae was always intended as a subdivision within the Reptilia (se e.g. Romer, 1933), and I have edited it accordingly. Phylogenetic classification really didn't take off until the 1990s, so I have also rewritten the last sentences a bit. I hope you find it an improvement. Petter Bøckman (talk) 11:00, 14 June 2012 (UTC)

Yes, definitely an improvement. I did think, though that using "have been" in the first sentence was a good compromise between "were" (my original verb) and "are" (your suggestion). The phrase "have been" doesn't always involve something exclusively of the past. As of today, my wife and I have been married 48 years—we still are! I have changed "based on purely shared ancestry" to "based exclusively on shared ancestry"; I'm not sure what pure sharing is. Peter M. Brown (talk) 12:19, 14 June 2012 (UTC)

Well, I suppose we here how subtle differences in meaning is interpreted differently depending on language background. For me as a Norwegian, the sentence reads "it's used to be that way, it isn't any more". I have shortened it a bit, retaining meaning (I hope!). The English understanding should take presidence over my Jonny Foreigner reading though, so please check that I have not bugged it up! Petter Bøckman (talk) 19:13, 14 June 2012 (UTC)

The lead, again

The lead now has the point of phylogenetic vs Linnaean classification twice, in the first and in the last section. Mentioning once in the lede really should do. It is not as if the article is about systematics only. Petter Bøckman (talk) 14:27, 5 March 2013 (UTC)

Ah, thanks Peter Brown! Petter Bøckman (talk) 07:47, 6 March 2013 (UTC)

Incorrectly {okay, controversially} states that the dinosaurs are extinct {edit: in the introduction unnecessarily and without citations}!

"Many groups are extinct, including dinosaurs," contradicts the dinosaur definition in the dinosaurs article, which states that "Birds are thus considered by most modern scientists to be dinosaurs and dinosaurs are, therefore, not extinct." (The widely-accepted definition of dinosaurs is a monophyletic one and thus includes modern birds.)

I would like to remove "dinosaurs" {{DavRosen withdraws the rest of this line/sentence to the right:}, or perhaps replace it with something like "the large dinosaurs,"}.

I would be willing to use a term like "non-avian dinosaurs" if someone can point me to a precise definition of this term, such that all "non-avian dinosaurs" are indeed extinct. DavRosen (talk) 23:16, 19 June 2013 (UTC)

The sentence you quote from Dinosaur is unverified; I have so tagged the paragraph. However matters are put, the statement should include the small dinosaurs—the 50 cm Xixianykus for example. Peter Brown (talk) 00:02, 20 June 2013 (UTC)

Given that the entire article is about a paraphyletic grouping (Reptiles, defined as non-avian diapsids), isn't it a bit silly to insist on monophyletic terminology within the page? HCA (talk) 13:33, 20 June 2013 (UTC)

Stating that large dinosaurs are an example of extinct reptiles does not logically imply that small dinosaurs are not -- this certainly isn't an exhaustive list of extinct reptiles! But let's put that aside. This article starts by giving a definition of reptiles qualified by the word "traditional" rather than stating it as a universal and uncontroversial definition today. In contrast, the second paragraph appears to be interpretable as making some of the same definitional assumptions (indirectly, by saying dinosaurs are extinct) without giving them the same qualification of "traditionally". One solution would be to qualify it: "Many groups are extinct, including dinosaurs (as originally/traditionally defined),". But that's an unnecessary distraction in the introduction.

When merely giving a few examples of something (of extinct reptiles in this case) in order to illustrate a statement, it's better to avoid such complexity and simply list uncontroversial examples! The dinosaurs can be brought up later in the context of discussing that "traditional" definition, with reference to the dinosaurs article. (And, btw, perhaps even moving some of the most detailed aspects of the avian exclusion issue to the dinosaurs article and including it here by reference rather than repeating it here redundantly?)

Also, some dinosaur species (and their individuals) have living descendants, regardless of whether these descendants are themselves classified as dinosaurs (and reptiles). Therefore, such dinosaur species are, at most, by definition, pseudo-extinct. Even if extinction is (or were to be) formally defined to include pseudo-extinction as merely a special case, or even if we can say that a taxonomic group can be "strictly extinct" (by which I simply mean extinct but not pseudo-extinct) while some of its constituent species are pseudo-extinct, many readers will jump to the conclusion that all members of the mentioned examples of extinct groups have no living descendants (i.e. they "died out" in lay terms). This is especially so because they may already hold this conclusion as a pre-conception from being told for decades that (all) the dinosaurs died out. The introduction of the present article is not a good place to elicit or explain these issues and subtleties, so let's simply not mention dinosaur extinction until later in the article!

DavRosen (talk) 16:26, 20 June 2013 (UTC)

But omitting dinosaurs from the list of extinct reptiles is omitting the most well-known example by far. That's like saying "During World War 2, The Allies consisted of several countries, including Canada and Australia" - technically correct but missing the main components. Maybe adding "(except birds)" afterwards? HCA (talk) 17:42, 20 June 2013 (UTC)

Yes, but some of the very aspects of the dinosaur extinction example that are the most "well-known" are, as we know, wrong. It's "well-known" that the dinosaur line was an evolutionary failure, a "dead end" that died out in a mass extinction. Quite to the contrary, the ancient dinosaurs as a group are arguably an amazing success story: their descendants (completely irrespective of whether we want to call them "dinosaurs" or not, which would change the terminology but not the facts or the science) constitute one of just a few remaining huge/diverse/entrenched groups of animals who dominate earth's ecosystem to this day. The birds' ancestors can no more be said to have failed or died out than can our own ancestors. We've got ancient ancestors who are just as pseudoextinct as theirs :-) DavRosen (talk) 22:35, 20 June 2013 (UTC)

While there are dissenters, your view that the ancient dinosaurs—meaning the Mesozoic nonavian dinosaurs—are an amazing success story is widely held among current paleontologists. Insofar as we can use Wikipedia to oppose the "well-known" popular views of the matter, let's do it!—though mostly in the Dinosaur article. The chronicle of Cenozoic birds is another story, though, and let's not get them confused. The survival of a few birds into the Paleocene, which in turn permitted survival to the present day, was an accident, not a result of superior adaptation to asteroid impacts. Peter Brown (talk) 23:09, 20 June 2013 (UTC)

While I'm generally a fan of promoting dinosaurs and correcting misconceptions about them, I don't think a small mention in the intro of an entirely separate article is the appropriate place to be doing so. The sentence has a clear purpose in the narrative - to communicate to the reader that, in addition to living taxa of this group, there are many prominent extinct taxa too, and to give a few prominent examples. The entire article is about a paraphyletic group, so it's not the place to insist on monophyly, and leaving dinosaurs out is just silly, so the only option left is a clarification. IMHO, this is the wrong place to start adding and explaining a new term, since it distracts badly from the main purpose of the sentence. It's much better, from my POV, to just have "excluding birds" with a link to the definition section of dinosaur. This way, the sentence isn't derailed, isn't inaccurate, and readers who are curious can just click on the link, while others can just move on. HCA (talk) 13:47, 21 June 2013 (UTC)

I disagree, and consider DavRosen's latest formulation the best proposal yet. While "pseudoextinct" is not a familiar term, his context makes quite clear what it means; no need to click on it. I don't see the "distraction" as serious. And my original formulation was inaccurate in that it implies that the nonavian theropod ancestors of birds are extinct, not merely pseudoextinct. Peter Brown (talk) 15:42, 21 June 2013 (UTC)

It's more than just "unfamiliar", it's outright rare. Google scholar only turns up a handful of references for it (especially once you weed out the stuff about nerve response and crystal structures), and I've never heard it before it was brought up here. I don't doubt its validity; I doubt the merits of including something so technical in the introduction of a page that focuses almost entirely on other taxa. What is gained by the inclusion? The sole issue with the original formulation was that, in using the paraphyletic "traditional/vernacular" definition of "dinosaur", it neglected that one type of dinosaurs, birds, are not extinct. The current version corrects that with a mere two words, while giving the reader a link if they wish to know more.

Whether dinosaurs (paraphyletic) are "extinct" or "pseudo-extinct" is a minor and highly technical disagreement that has no place on the introduction of an encyclopedia intended for the general public. Look at snake - in the very first sentence, it described them as "legless", in spite of the fact that many species have vestigial limbs. Yet we leave it that way because the introduction is no place for such technical hair-splitting - they are functionally legless, and anal spurs are explained later in the page. If you wind up placing strict, technical accuracy above readability, you get things like the Wikipedia math articles, which are utterly useless to anyone without at least an MS in mathematics. HCA (talk) 17:16, 21 June 2013 (UTC)

Okay, if the term pseudo-extinct is too technical, then maybe we can avoid it, at least here in the summary/lead. But [I opine that] it's still important that we not (even inadvertently) perpetuate the belief that the dinosaurs actually "died out", which itself is not a "technical" point but a fundamental misunderstanding that many or most non-technical readers may hold.

We've already qualified the definition of reptile by using the word "Traditionally" (even though using that definition without the qualification would be less controversial than doing so with dinosaurs -- I don't see as many calls for using the term Reptile monophyletically). If the term "traditional" isn't too technical, let's use it here and briefly clarify that they have living relatives without using "pseudo-extinct" here.

DavRosen (talk) 17:55, 21 June 2013 (UTC)

I understand the reasons for the most recent change (HCA), but the problem with "are extinct but their descendants, birds, remain." is that this will sound like a contradiction in terms to many or most lay readers. We need to give them a fighting chance to understand what we mean by that, even without reading the rest of the article. I'd said "are extinct but have survivors in an evolved form: the birds." because this may enable them to resolve the seeming contradiction: the dinosaurs are extinct even though they have living descendants because we [traditionally] consider those descendants to be a different/distinct/separate/evolved group rather than considering them to be dinosaurs. We don't want to say this too verbosely in the lead/intro, but leaving many readers of the intro puzzled at a seeming contradiction is not conducive to their learning :-)

Also it seems like we're editing to change emphasis rather than questions of fact, which is okay in itself. But then I think that we should emphasize making statements (especially in the intro/lead where there's no space to elaborate) that remain true under any plausible definition, over statements that are true if we use the definition that we may favor but isn't universally accepted (if you believe exclusion of birds from dinosaurs is universally accepted among good sources then please fight that battle on the Dinosaur page before here).

Here are some alternative statements/facts to consider including in some way if we must mention dinosaurs in the intro:

1. Dinosaurs have living descendants today (true for any plausible definition of dinosaur)

2. Dinosaurs are extinct (true if we define dinosaurs such that birds are not dinosaurs, i.e. "traditionally", but ambiguous to many readers because extinct is often used and understood by lay people in a sense that implies "died out" with no living descendents)

3. Dinosaurs are not extinct (true if we define dinosaurs monophyletically, which remains controversial [at best], but has gained some ground, but otherwise ambiguous because it may easily be misunderstood to mean there are still traditionally-defined dinosaurs alive today)

4. Many/most subgroups of dinosaurs are extinct (true, but vacuous because it could be said about almost any major group, and redundant if we say 2.)

This is why I think we should emphasize (1.), and include (in intro/lead) the others only to the extent that we can adequately minimize puzzlement and frustrating perceived contradiction.

DavRosen (talk) 20:15, 21 June 2013 (UTC)

BTW, about the phrase "an evolved form", HCA correctly pointed out that "all forms are evolved". What I was trying to convey was something like "a form, descended from given group, that has changed so much that they're no longer considered part of that group" (and the original group is now extinct unless they have other members who haven't changed "so much").

I'm picturing a single-frame cartoon with what appears to be an early bird (not the kind that gets the worm), imploring his relatives, "stop evolving so fast -- you're making more of our ancestors extinct".

DavRosen (talk) 21:03, 21 June 2013 (UTC)

"Dinosaur (traditionally defined)" is meaningless. Taxa have not traditionally had definitions in the classic sense of necessary and sufficient conditions, a sense introduced by Aristotle and the Stoics and retained today in areas like philosophy and mathematics. True definitions of taxa were not provided in a consistent way until Hennig's 1950 publications, and these were hardly "traditional". A genuinely traditional approach, formulated by Strickland in 1842, was to introduce a taxon by providing a type and a diagnosis. This diagnosis is not a definition; it is, according to the ICZN, "A statement in words that purports to give those characters which differentiate the taxon from other taxa with which it is likely to be confused." If, in the light of further discoveries, the statement no longer does what it "purports", the diagnosis is refined. Definitions, on the contrary, are immutable. The formulations produced by the likes of Laurin, Cantino, and de Queiroz are true definitions, and these writers take this immutability as a virtue. In no sense, however, are their formulations "traditional". Peter Brown (talk) 21:30, 21 June 2013 (UTC)

Peter, I'm not married to the term "traditional" -- I'm open to ways of removing or replacing that term.

HCA, could you elaborate on what specific facts you most want to convey about dinosaurs in the context of reptile extinction examples in the intro? I realize "dinosaur extinction" is "well-known" and so shouldn't be ignored, but if we include something about it we should make sure we aren't giving or confirming misconceptions (that the dinosaurs were wiped out), or appearing to contradict ourselves because we've relied primarily on terms ("extinct") that are frequently understood to mean something ("wiped out") other than what we mean by it ("group having no living descendents that are still members of that group").

DavRosen (talk) 23:18, 21 June 2013 (UTC)

The central fact that the sentence should convey, IMHO, is that reptiles (defined paraphyleticly in this article) include not only extant groups, but also a number of major extinct taxonomic groups (paraphyletic and otherwise). IMHO, we can't leave dinosaurs out, because they're so prominent in the general consciousness. However, we also shouldn't spend more of the sentence clarifying dinosaur taxonomy than on the central point - that some very successful and diverse groups of reptiles are extinct.

I'm also not sure that members of the public would have a problem with declaring a group extinct but having surviving descandants - after all, their great-grand parents are dead, but they're surviving descendants. That's a crude analogy, but remember that we're not necessarily even dealing with people who've had high-school biology (or maybe who forgot it all). If I say "all members of X are extinct" about a paraphyletic grouping (or even a polyphyletic grouping), I'd naturally assume that just means that all members of that group are dead, without including the excluded taxa. HCA (talk) 00:05, 22 June 2013 (UTC)

In my experience, most people would call their great-grandparents dead but would never call them extinct. Extinct often conveys a sense of finality of a branch, in popular usage. The word extinct is a form the same root as extinguish. Consider "There was once a Rosen family in France, but it went extinct. I'll introduce you to their great-grand children, Mrs. Smith and Mr. Jones. DavRosen (talk) 21:40, 22 June 2013 (UTC)

True, but that leaves us with the issue of how much clarification is needed. I'm still in favor of my "(except birds)" modifier, with birds linking to the dinosaur page's definition section. I definitely don't think this is the place to get into the finer points of terminology or monophyly vs paraphyly. HCA (talk) 21:58, 22 June 2013 (UTC)

If we aren't willing to clarify or get into the finer points, then we can't include statements whose truth or likely interpretation is greatly dependent on those fine points.

You could call any living group, paraphyletic or not, "an extinct group (except {list remaining subgroups here})". To me, saying "the dinosaurs are extinct (except birds)" is just a slightly more specific version of the vacuous statement "the dinosaurs are extinct (except those that aren’t)" and makes no more sense than saying "the vertebrates include many extinct groups, such as the reptiles for example (except testudines, lepidosaurs, and crocodilians)".

On the other hand, if dinosaur is defined to exclude birds (which it needn't be simply because reptiles are), then it makes no more logical sense to say dinosaurs are extinct "(except birds)" than it does to say dinosaurs are extinct "(except fish)".

So the "(except birds)" formulation isn't a good one no matter which way you define dinosaurs.

Can you tell us, did the dinosaurs lose (in the die out sense) a much larger percentage of their subgroups than reptiles overall, or than other large groups of reptiles that still have descendants? Maybe something along these lines instead of trying to make an oversimplified/misleading blanket statement about dinosaurs. But we shouldn't exaggerate or oversimplify dinosaur extinction just because it's familiar in some form and we don't want to clarify it (in the intro/lead).

DavRosen (talk) 02:42, 24 June 2013 (UTC)

I disagree. If we accept a paraphyletic taxon as valid, even for informal purposes, we can define that taxa as extinct, even if the monophyletic version has descendants, which is what I'm trying to do with "(except birds)" - I'm trying to simply, clearly, and effectively communicate that the *paraphyletic* group "dinosaurs (except birds)" is entirely extinct. Perhaps there's a better phrasing than mine, but I still think if we just communicate that we're talking about the paraphyletic grouping of dinosaurs, everything becomes simple. Maybe "non-avian dinosaurs"? or "Dinosaurs paraphyletic"?

Like I said above, some level of simplification, even glossing over significant facts, is necessary and unavoidable - look at the snake page, which in the very first sentence describes them as "legless" in spite of the vestigial limbs in many taxa. Simplification is not the same as oversimplification, and from a teaching standpoint, one of the most important things is knowing the difference. Oversimplification misleads, but simplification can elucidate broad rules that, while they have exceptions, are tremendously useful for understanding. Get bogged down in every little detail and exception, and your students/readers/audience will never actually grasp the broader pattern. I would argue that using the paraphyletic definition of dinosauria in this sentence counts as simplification, not over-simplification. HCA (talk) 14:15, 24 June 2013 (UTC)

By trying to communicate something about only paraphyletic dinosaurs and nothing about monophyletic dinosaurs in the intro, you are emphasizing one while excluding the other, which contradicts the wikipedia principle of neutral point of of view (on that controversial definitional question about dinosaurs). The fact that this is an article about reptiles, which we agree is a paraphyletic grouping, is irrelevant to the dinosaur question. For those who use the term dinosaurs monophyletically, it follows that the reptiles then simply don't include all the dinosaurs, by definition.

If we aren't willing to add enough to the intro to give some due to both dinosaur definitions (in a way that readers aren't likely to fundamentally misinterpret) rather than assuming one and relegating the other to the other sections of the article, then we shouldn't say dinosaurs are extinct in the intro -- we can say it below where there is enough "room" to explain it.

In addition, if we aren't willing to add enough to intro to clarify "extinct" enough so that the average reader isn't likely to fundamentally misinterpret (at least the uncontroversial part of) what we're saying about a given group, then we shouldn't use that word in such a case. If we think the difference between a group being "extinct" vs "died out" vs "most subgroups died out" vs "their only surviving lineage is..." is a techinical detail that doesn't need to be clarified in the intro, then we can just as easily choose the least ambiguous of those terms. Are the following accurate?

The word lineage encompasses the group *and* their descendants so it doesn't take a position on whether the birds are members or descendants. But it has to be clear that this is one of the dinosaur lineages as well as of course being a bird lineage. Instead of dinosaurs simply being extinct, we can use the term extinction in a way that does not necessarily imply a single fact (dinosaurs are extinct) but rather a process, one of whose outcomes is that (only) the birds are still living today. One way is to use the term "Mass extinctions" (plural) or "Widespread extinction". Another is to make birds or their lineage an exception/survival/escape from the dinosaurs "dying out" or being "wiped out", rather than as an exception to their "extinction".

[note: see also a couple of different types of alternatives down below this list]

1. Dinosaur extinction wiped out all their lineages except birds.
2. Extinction wiped out all the dinosaur lineages except birds.
3. Extinction wiped out all but one of the dinosaur lineages, [in] the [form of] birds.
4. Only the birds escaped dinosaur extinction.
5. All the dinosaurs died out in extinctions, except their bird lineage.
6. All the dinosaur lineages died out in extinctions, except birds.
7. Mass extinctions of dinosaurs spared {left only?} one lineage, [in] the [form of] birds.
8. Widespread dinosaur extinction left only the bird lineage remaining.
9. Dinosaur extinction spared one lineage, the birds.
10. Only one one dinosaur lineage, the birds, escaped mass extinctions.
11. After mass extinctions of dinosaurs, only their bird lineage remained.
12. Mass extinctions of dinosaurs left a sole surviving lineage in the form of birds.
13. Mass extinctions wiped out all the dinosaurs except their bird lineage.
14. Widespread dinosaur extinction spared {left only?} one lineage, [in] the [form of] birds.
15. Only one one dinosaur lineage (birds) escaped extinction.
16. After widespread dinosaur extinction, only their bird lineage remained.
17. Widespread extinction of dinosaurs left a sole surviving lineage in the form of birds.

Or how about one of these, leaving open both possibilities for whether birds are or aren't dinosaurs:

I. Many groups are extinct. For example, the only dinosaurs or dinosaur descendants who remain today are the birds. The pterosaurs and aquatic groups such as the ichthyosaurs have no living descendents.

II. Many groups are extinct. For example, pterosaurs and aquatic groups such as the ichthyosaurs have died out. And the only dinosaurs or dinosaur descendants who remain today are the birds.

III. There are many extinct groups. Pterosaurs and aquatic groups such as the ichthyosaurs have no living descendants at all. The only dinosaurs or dinosaur descendants who remain today are the birds.

DavRosen (talk) 18:07, 24 June 2013 (UTC)

I like the idea of re-focusing to the mass extinction part of it, as well as the phrasing "Dinosaur extinction wiped out all their lineages except birds". Perhaps they could be combined? Something like "In addition to the living reptiles, there are many diverse groups which are now extinct, in some cases due to mass extinction events. In particular, the KT extinction wiped out the pterosaurs, ichthyosaurs, plesiosaurs, and all dinosaur lineages except birds."? HCA (talk) 18:31, 24 June 2013 (UTC)

Done! I count about 4000 words of discussion :-) Keeping this entry short. DavRosen (talk) 20:03, 24 June 2013 (UTC)

Hmmm, wouldn't this be better: "all dinosaur lineages except those giving rise to birds."? After all, the "bird lineage" isn't just the birds themselves, but also includes their not-[yet-]bird dinosaur ancestors as well (constituting anyway a small but eventually-important subset of all the dinosaurs). DavRosen (talk) 21:21, 24 June 2013 (UTC)

"Giving rise to" covers a lot, including theropods as a whole. I like the current version, because whether or not "birds" is just the crown group or includes extinct species, it's true (the lineage did survive), and it explicitly considers birds a sub-group of dinosaurs. That some birds of the time went extinct isn't really special - the KT event severely damaged every clade at the time, including those who didn't go totally extinct (crocs, turtles, snakes, fish, mammals, inverts, everything). HCA (talk) 21:39, 24 June 2013 (UTC)

Good point about entire groups that "gave rise to". I was thinking in terms of the individuals (or maybe species) that are ancestral to birds but aren't birds themselves (but are dinosaurs). I'll think about it a little more. I'm not concerned about birds that went extinct -- we didn't say that all bird species and individuals survived, just that we're excluding them (or their lineages) from the subset (of dinosaur lineages) whom we are asserting were wiped out (i.e. we aren't claiming it's an exhaustive specification of all "wiped-out" dinosaurs/birds). DavRosen (talk) 22:56, 24 June 2013 (UTC)

Dinosaur "extinction"

This is about the statement in first paragraph of article that extinct species "included pterosaurs, pelycosaurs, and dinosaurs." The average reader may interpret this to mean or imply or favor the view that "dinosaurs are extinct" (regardless of whether the precise wording logically implies the statement "dinosaurs are extinct" to an astute reader).

Stating or giving the impression (esp. in intro/lead) that dinosaurs are "extinct" is elevating the POV that dinosaurs should be defined so as not to include birds, to the exclusion of the other valid POV: that birds are members of dinosauria, in which case there are living dinosaurs today.

Afterwards it says "(Among dinosaur species were some ancestral to birds, .....)" which has a similar effect: it gives the impression that birds are not dinosaurs (controversial POV), but rather are descended from dinosaurs.

We recently had a long discussion here about dinosaur extinction and I thought the consensus was to avoid favoring this POV, or in this case, writing something in the intro/lead that many readers will [mis]interpret in a way that appears to be more consistent with one POV than the other.

DavRosen (talk) 20:08, 28 June 2013 (UTC)

POVs are OK if they're attributed. We can start with the statement that birds are descended from Triassic dinosaurs—this is totally uncontroversial. We can then add, with references, that many paleontologists go further, considering birds to be a kind of dinosaur. On this view, we can point out, dinosaurs aren't really extinct, since there are species living today. Peter Brown (talk) 21:15, 28 June 2013 (UTC)

We're talking about the first paragraph of the article -- this isn't the place to delve into the specifics of controversies about whether some non-reptiles (the birds) are, or are not dinosaurs. It should start by saying things that are not biased toward giving impressions that are false or controversial, either directly or through predictable "mis"-interpretations by readers.

It also isn't the place to make use of subtle distinctions between extinction of groups vs some or all of their species, in order to make it technically true while still leaving many readers with a different or ambiguous impression.

We had already resolved these questions for paragraph 4 -- I don't know why we have to go through it all again just because someone wants to put it into paragraph 1. I'm thinking to just move the wording that we'd agreed on up into paragraph 1. Having it in both places is redundant.

Also the very first paragraph is not the place to go into the historical development of what's considered a reptile. It should just tell what a reptile is (today) in the simplest possible terms.

DavRosen (talk) 21:50, 28 June 2013 (UTC)

The common way of expressing the phylogenetic relationship between dinosaurs and birds is that "birds evolved from dinosaurs". In this way of expressing phylogeny (evolutionary taxonomy), dinosaurs are extinct, just as mammal-like reptiles are. However, the section in question could use some fine-tuning. Dinosaurs should come first, as they are by far the best known fossil group, and they should not be split up into two somewhat obscure orders, and particularly not with other groups in between! It is also perfectly possible to express things in a way that uses an evolutionary taxonomic wording, but specify that birds are dinosaurs. Here's my suggestion:

In addition to the living reptiles, there are many diverse groups that are now extinct, in some cases due to mass extinction events. In particular, the mass extinction ending the Mesozoic wiped out the dinosaurs with only their bird descendants surviving, but also pterosaurs, plesiosaurs, as well as many species of crocodilians and squamates, like the mosasaurids.

Better? Petter Bøckman (talk) 19:14, 27 July 2013 (UTC)

Not really, the current version is more specific in enumerating which groups went extinct. Dinosaurs as a group did not go extinct, but ornithischians, sauropods, etc. did. In this context breaking down "dinosaurs" into constituents conveys more information without the misleading use of "their descendants" for birds. Another, more current way to put this would be that all stem-birds or bird-line reptiles, including pterosaurs and many groups of dinosaurs, became extinct. But this conveys much less information about the casualties of the extinction. MMartyniuk (talk) 20:16, 27 July 2013 (UTC)

It would also be very misleading to all but a very small group who would know what a "stem bird" is. Even the scientific literature uses the term unevenly. Petter Bøckman (talk) 20:45, 27 July 2013 (UTC)

Amphisbaenia

In the lead, if snakes and lizards are mentioned, should amphisbaenids be mentioned too, as being equivalent in ordering?--Richardson mcphillips (talk) 21:31, 7 October 2013 (UTC)

Maybe? On one hand, they're a much smaller and less diverse lineage, and ranks above species don't really have any objective scientific criteria (a genus of beetles may be comparable to an order of mammals in some ways). Plus, splitting out snakes and amphisbaenians makes lizards not just paraphyletic but polyphyletic. However, you're absolutely right that they *are* currently ranked as a sub-order. Then again, is the lede really the place to bring up smaller lineages, especially considering how vastly outnumbered they are by snake and lizard species? I'm pretty ambivalent, but lean weakly towards not in the lede. HCA (talk) 23:45, 8 October 2013 (UTC)

Reptile diagram

I know science, but not all WP readers do. The caption for the reptile diagram makes sense to me but will leave some readers cold. It reads: "The traditional class Reptilia (green field) is a paraphyletic group comprising all non-avian and non-mammalian amniotes." The interesting point about using the term Reptilia in a cladistic sense is relegated to a note. I tried reworking the caption to reach a more general audience, and the change was reverted as too informal. Would someone else care to try making the diagram more understandable to lay readers? I've done focus groups where I watched adults try to read for comprehension, and my estimation of the average reader's ability to parse scientific content is not high. Also, are there WP guidelines about how formal the tone should be? Or is it a matter of taste? That's not a rhetorical question; I really want to know.

My text read: "The original class Reptilia (green field) was defined in 1768, before scientists understood evolution. Because the "reptiles" class excludes mammals and birds (aves), it doesn't count as a clade, which is a group defined by descent. Some workers in phylogenetic nomenclature employ the term "Reptilia" in a more restrictive sense, for the clade Sauropsida."

I'm not an expert on evolution and cladistics, but I'm something of an expert at writing clear exposition for a general audience. I'm also a fan of WP:JARGON. Leadwind (talk) 22:01, 7 May 2014 (UTC)

Reptile vs Reptilia

I came to this article via Reptilia. For those interested in in reptilia, this article is a poor source (it is like trying to pick needles out of a haystack, and the hay has almost no relationship). Is it really necessary to include both the topic of reptile and reptilia together rather than separately? Reptile and reptilia both have enough content (nearly all of it not even overlapping) to deserve separate articles. — al-Shimoni (talk) 20:55, 6 July 2014 (UTC)

You may be looking for Sauropsida, also known as Reptilia (clade). In English "Reptilia" is usually taken as a synonym for "Reptilia (class)," the paraphyletic group Reptile, i.e., all members of the clade Amniota except birds and mammals, where "mammal" is defined in the broader sense as Mammaliaformes, i.e., crown mammals (Mammalia) plus stem mammals and their non-crown descendents (i.e., basal mammals). Ideally both this article and the one on Sauropsida should mention this in the lede or a hatnote. Zyxwv99 (talk) 17:46, 1 February 2015 (UTC)

I forgot to mention another definition of reptile: all amniotes except mammals and synapsids (ref). Zyxwv99 (talk) 02:34, 2 February 2015 (UTC)