Talk:Dinosaur

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First Line, cladistics vs. phylogenetics

The first line states that dinosaurs are an extinct group of "reptiles".

Considering that reptiles are a polyphyletic group (crocodiles are more closely related to birds than they are to turtles), should this be changed to the undeniable "dinosaurs are an extinct group of animals"? —Preceding unsigned comment added by DonDaMon (talk • contribs) 03:56, 5 August 2010 (UTC)

Why are "reptiles" necessarily a polyphyletic group? Some definitions of reptile are monophyletic and include birds. No definitions are currently governed by an official body. And no convention exists saying non-monophyletic groups are automatically invalid in all taxonomic systems. The PhyloCode isn't in effect yet so it remains to be seen if Reptile will get an official definition, and what it will be. MMartyniuk (talk) 04:39, 5 August 2010 (UTC)

Reptiles says that reptiles are necessarily cold-blooded. So dinosaurs can't be called reptiles. I think the line should be removed. Erikmartin (talk) 18:25, 7 August 2010 (UTC)

The article is wrong. Even some sea turtles are warm blooded. MMartyniuk (talk) 01:25, 8 August 2010 (UTC)

From what I know, scientists think that some dinosaurs were warm blooded, such as the ones that evolved into birds. Can you provide me with information about those sea turtles Mmartyniuk? I've never heard that before!Chipmunkdavis (talk) 02:41, 8 August 2010 (UTC)

See the leatherback turtle. Albertonykus (talk) 05:08, 8 August 2010 (UTC)

This was changed a long time ago by some editor. The definition used to say reptile like with a footnote explaining what the problem was calling them reptiles. I support removing the word reptile and using something more precise. JPotter (talk) 03:15, 8 August 2010 (UTC)

I support removing this line. I see nothing that relates this article to specifically non avian species. Also, this is contradicted in the very next paragraph "Dinosaurs are a diverse and varied group of animals; birds, at over 9,000 species, are the most diverse group of vertebrate besides perciform fish.[2] Paleontologists have identified over 500 distinct genera[3] and more than 1,000 different species of non-avian dinosaurs."

That said, it is arguable that dinosaurs are extinct; that depends on whether you consider birds a different group of animals or the same group. But I do feel that the extinct definition is the most common. For discussion, I propose replacing it with "Dinosaurs were a diverse group extinct animals. Exact definitions vary, with some specifying only avian dinosaurs and some including avian dinosaurs and prehistoric reptiles." --Mech Aaron (talk) 16:36, 30 August 2010 (UTC)

No one has explained why it's incorrect to include them as reptiles. Reptilia has been phylogenetically defined, just as dinosaur has. There is also nothing incorrect about calling birds reptiles. Birds are a sub-group of reptiles just as mammals are a sub-group of synapsids. Also, the taxobox lists Class Reptilia. Perhaps it should be Reptilia & Aves? MMartyniuk (talk) 02:18, 31 August 2010 (UTC)

Well this article is about non-avian dinosaurs, which is a polyphyletic group anyway, so worrying about the polyphyletic nature of reptiles is probably not a major issue here. Icalanise (talk) 22:11, 8 August 2010 (UTC)

"Reptile" currently doesn't really mean anything. It used to be used as the group containing the last common ancestor of turtles, lepidosaurs, crocodilians, and a whole host of extinct forms. This was broken down into Anapsids (very basal reptiles and turtles), Diapsids (archosaurs, lepidosaurs, and relatives), Synapsids (mammals and extinct forms), and Euryapsids (polyphyletic grouping of marine diapsids). What this means is that, last time Reptile meant something, it meant the last common ancestor of humans and hummingbirds, as well as turtles and tuataras. However, apparently somebody decided he didn't like the connotation of "mammal-like reptiles" and came up with this word "Amniote," which is synonomous with the only possible definition of a monophyletic Reptilia, which, of course, no longer exists.

In light of this, then, Reptile only has the definition given to it by Linaean taxonomy and popular usage. As in it really does mean just snakes and turtle and crocs. I mean, sure, it's a ridiculous definition, but no one really uses it as a clade because they don't like the idea of saying humans are reptiles, even though it IS just a word, but my feelings are irrelevant here. Point is that only some dinosaurs are reptiles, so saying "dinosaurs are reptiles" is technically incorrect. I don't have a problem with it, because I use reptile as if it were amniote just so people can understand me, but, again, my opinion does not change the fact that reptile's only defintion is a non-monophyletic one, and feels out of place when right below this editing window I can see the line "Encyclopedic content must be verifiable."

Fun fact, the same thing happened to fish. Because humans don't want to say they are fish for some reason, no version of "fish" or "Ichthians" or anything appears as a real name in any cladogram. Furthermore, it doesn't even appear in Linnaean taxonomy, so this word is completely subjective, not just paraphyletic. But, thats something for ichthyologists to figure out.Cultistofvertigo (talk) 03:47, 12 September 2010 (UTC)

Well, Pisces was historically used for fish in Linnaean taxonomy. And I'm almost certain at least one author has defined Repitilia as a clade nearly synonymous with Sauropsida, but I'd have to dig around for the cite. Reptilia is still used often in scientific literature, for example this paper from only a few months ago.[1] MMartyniuk (talk) 05:51, 12 September 2010 (UTC)

I support removing the bald statement that dinosaurs are/were "reptiles". As a casual reader of this article with no specialist knowledge, I found the opening to the article most confusing. It seems to be logically inconsistent. (If the only surviving descendants of dinosaurs are the birds, then the ancestors of reptiles cannot have been dinosaurs, so, logically, dinosaurs cannot have been reptiles.) Having read through the above comments, (and understood a small proportion of them), I see that things are not that simple. But it is surely bad form to start an encyclopaedia article with paragraph that throws the casual reader into confusion. GrahamN (talk) 15:26, 27 September 2010 (UTC)

Dinosaurs are reptiles, though. Abyssal (talk) 15:46, 27 September 2010 (UTC)

Would you say that birds are reptiles? GrahamN (talk) 15:59, 27 September 2010 (UTC)

In a phylogenetic sense, yes they are. See [2]. de Bivort 16:18, 27 September 2010 (UTC)

OK, so if I have understood this correctly, dinosaurs are reptiles only in the same sense that birds are reptiles. I think that makes the point. Try changing the opening sentence of the Bird article to "Birds are a diverse group of reptiles", and see what the reaction is! The word 'reptile' has a general meaning in the English language that evidently doesn't correspond to the taxonomic term Reptilia. This is an English language encyclopaedia, aimed at a general readership - it's not a specialist taxonomists' website. GrahamN (talk) 19:30, 27 September 2010 (UTC)

It's fine to use "reptile" here because dinosaurs are reptiles in both the technical and colloquial meanings. It would be problematic at Bird because birds are only reptiles in the technical, not colloquial meaning. de Bivort 20:41, 27 September 2010 (UTC)

But the first paragraph makes it clear that dinosaurs aren't reptiles in the colloquial sense. It says that they are the ancestors only of birds, which means that what I think of as reptiles - snakes, lizards, turtles and such - must belong to some completely separate group (or groups) of animals. That is exactly the contradiction that confused me whan I read the article, and what prompted me to come to this talk page. If you are only aware of the colloquial meaning, as I was, the paragraph firstly states that dinosaurs are reptiles (colloquial) and immediately goes on to say (indirectly) that they are unrelated to reptiles (colloquial). As it stands the paragraph is extremely confusing to the lay reader. It needs fixing somehow. GrahamN (talk) 21:12, 27 September 2010 (UTC)

I am not opposed to trying to clarify it, but you should realize that "being the ancestor of birds" does not imply that they are not "reptiles in the colloquial sense." So I don't think there is any contradiction. Can you propose a clarification? de Bivort 21:22, 27 September 2010 (UTC)

Being the ancestor only of birds (and not of any colloquial reptiles) means that they cannot be in the same group as colloquial reptiles. So in my book that means they aren't colloquial reptiles! But I can see I'm not going to win this argument. GrahamN (talk) 01:19, 28 September 2010 (UTC)

That's not how classification works. 99.99% of extinct animals are not the direct ancestors of something modern. Modern reptiles don't share a common ancestor exclusive of dinosaurs, pterosaurs, ichthyosaurs, mosasaurs, aetosaurs, or even Deinosuchus. Your proposal would place all living forms and every extinct species in individual, independent groups. This is equivalent to abandoning the idea of classification altogether. A "reptile" is either an animal that possesses certain defined traits (egg-laying, scales, four limbs, etc.) or falls within a defined group (all animals closer to crocodiles, lizards and turtles than to mammals). Most dinosaurs are reptiles under the first definition, all are under the second. MMartyniuk (talk) 23:21, 4 October 2010 (UTC)

You do realize that your argument is equivalent to saying that my aunt cannot be part of my family because she is the ancestor of my cousin? --Khajidha (talk) 13:56, 4 October 2010 (UTC)

Non-avian dinosaur vs. Dinosaur

This section seems a bit weird and overly semantic: "From the point of view of cladistics, birds are dinosaurs, but in ordinary speech the word "dinosaur" does not include birds. Additionally, referring to dinosaurs that are not birds as "non-avian dinosaurs" is cumbersome. For clarity, this article will use "dinosaur" as a synonym for "non-avian dinosaur". The term "non-avian dinosaur" will be used for emphasis as needed." The whole point of cladistics is that there isn't anything that can be said about dinosaurs as a whole that can't also be said about birds. The next sentence goes into a general description, the only bit of which that doesn't apply to birds is where it says they're extinct (which contradicts the intro). Is it really important to waste a paragraph explaining the way the article sets up this distinction, which smacks a bit of OR anyway? Yes, many sources use non-avian dinosaur, but in which specific instances in this article is it useful? MMartyniuk (talk) 07:23, 29 September 2010 (UTC)

It would indeed be highly preferable if the text would treat the dinosaurs as a whole, that is: including birds. Of course, that would mean that every statement had to be carefully checked whether it would still be correct when referring to all dinosaurs. Often, by the way, the real distinction to be made is not "avian" versus "non-avian" but "Cenozoic" versus "Mesozoic" or even "extant" versus "extinct".--MWAK (talk) 17:22, 29 September 2010 (UTC)

This is true whether or not birds are included. Dinosaurs are so diverse even excluding birds, it would be easy to overlook a generalization that actually excludes some forms. Talking about the number of digits, for example, could ignore the fact that some dinosaurs lack digits. MMartyniuk (talk) 05:19, 30 September 2010 (UTC)

consolidating sections

Hi all - many people are responding to what seems to be a single issue spread across many sections, so I would propose we use this section to discuss the topic above. To me it boils down as follows:

• In a cladistic interpretation, Dinosaurs (like birds) are reptiles because they are part of Reptilia.
• In a colloquial interpretation, Dinosaurs (unlike birds) are reptiles because they are scaly (or whatever).

To what extent should both of these interpretations be represented in the lede?

• My personal opinion is that both definitions should be acknowledged. de Bivort 22:08, 29 September 2010 (UTC)
• Both should be discussed, but only the cladistic one represents real science, and it should be treated as the correct one. Abyssal (talk) 03:38, 30 September 2010 (UTC)

I agree both should be discussed, but FYI, it's totally legitimate in science to refer to groups of organisms that aren't clades. Invertebrates have a retinal light current, vertebrates a dark current. Flying animals have adaptations to lighten their bones. etc.. de Bivort 04:34, 30 September 2010 (UTC)

It's legitimate, but is it actually done? If not, it's OR. What source defines dinosaurs as something other than a clade? Here's Webster's definition [3] which also specifically includes non-dinosaurs as they're spoken of colloquially. But this is a science article, and any popular, vernacular definitions, should they deviate from scientific use (which this obviously does), should be relegated to the culture section. MMartyniuk (talk) 05:21, 30 September 2010 (UTC)

Yes it's done, an exceedingly common example is to speak of the common selective pressures on organisms that occupy the same ecological niche, regardless of their phylogenetic relationships. Anyways, no one is saying that dinosaurs aren't a clade! Reptiles, in a colloquial sense, are not. Importantly, this is not a science article - it is not peer-reviewed. It is a collation of secondary sources [4] intended for the widest possible audience [5]. de Bivort 13:03, 30 September 2010 (UTC)

Dinosaurs in a colloquial sense aren't either. In a phylogenetic sense, Reptilia is also a clade, since it has been given (several) cladistic definitions over the years, just like Dinosauria. Why are we preferring the colloquial use of Reptile but not Dinosaur? MMartyniuk (talk) 23:40, 30 September 2010 (UTC)

Invertebrate and flying animal are never considered clades in science, but dinosaurs are. 219.87.82.162 (talk) 05:19, 30 September 2010 (UTC)

See above. de Bivort 13:03, 30 September 2010 (UTC)

A severe problem is also that there is not a single colloquial "definition". In the vernacular, the concept has a very vague denotation. To many, any large and prehistoric animal is a dinosaur, including mammoths. Therefore to them it is a contradictio in terminis to call birds dinosaurs — they are small and living. Such prescientific notions have to be distinguished from the scientific concept of a paraphyletic Dinosauria: dinosaurs without birds. This last concept has no legitimate place in the lead section as it is too irrelevant, being out-dated science.--MWAK (talk) 07:17, 30 September 2010 (UTC)

Let's not overcomplicate the issue. We don't have to go into it much. Something like, 'birds are regarded as part of the dinosaur clade, but this article will not treat of them'.Gazzster (talk) 20:58, 30 September 2010 (UTC)

As I mentioned in the section above, such a distinction is useless. Anything that can be said about "dinosaurs" can also be said about birds (or sauropods, or heterodontosaurids, or abelisaurs). If it can't, it shouldn't be in this article, but rather at some more specific level. Statements like "there are no flying dinosaurs or marine dinosaurs" is just as false as "no flying or marine mammals". Actually, that one WAS true in the Mesozoic... Alos, keep in mind that many people define Aves as the crown group, so it's still not true of dinosaurs, since according to many authorities, Hesperornis and Ichthyornis etc. are also non-avian dinosaurs. MMartyniuk (talk) 23:42, 30 September 2010 (UTC)

Why would you deliberately choose from the outset to make the article misleading? Abyssal (talk) 21:29, 30 September 2010 (UTC)

Agree that, as written, the sentence you propose there is misleading. Birds are part of the dinosaur clade. No qualification needed. de Bivort 22:35, 30 September 2010 (UTC)

Footprints pull origin and diversification of dinosaur stem lineage deep into Early Triassic

Stephen et al. (2010) Footprints pull origin and diversification of dinosaur stem lineage deep into Early Triassic. Proceedings of the Royal Society B. doi:10.1098/rspb.2010.1746--Diucón (talk) 18:33, 6 October 2010 (UTC)

Dinosaur stem lineage, not dinosaurs themselves. This is covered at Dinosauromorpha. MMartyniuk (talk) 01:23, 7 October 2010 (UTC)

There is a conversion error at this location in the article at this sentence: "The planet's temperature was also much more uniform, with only 25 °C (45 °F) separating average polar temperatures from those at the equator." Assuming that 25 C is correct, the temperature in Fahrenheit is 77 not 45.

I would change it myself but seem to be unable to edit this article

Aatkin (talk) 19:38, 12 October 2010 (UTC)

The 25 °C (45 °F) is correct. This is not a listing of an actual temperature, but a DIFFERENCE in temperatures between two places. A difference of 25 Celsius degrees is the same as a difference of 45 Fahrenheit degrees. --Khajidha (talk) 18:44, 26 October 2010 (UTC)

If dinosaurs are reptiles

And birds are dinosaurs, then wouldn't that mean birds must be reptiles? 209.86.226.25 (talk) 01:31, 14 October 2010 (UTC)

Correct, in the cladistic system (but not the Linnaean system used in the info boxes), birds are reptiles. MMartyniuk (talk) 01:41, 14 October 2010 (UTC)

dinosaurs are not extinct, they have been spotted in numerous backyards, jungles and forestrial and industrial parks —Preceding unsigned comment added by 142.162.35.112 (talk) 12:44, 11 November 2010 (UTC)

Birds are dinosaurs, but the African cryptids are likely to be a myth. Crimsonraptor (talk) 18:50, 12 December 2010 (UTC)

Birds are not reptiles. When you say "are" you imply their current status. Birds, as the contemporary theory goes, descended from reptillian ancestors. Just as man descended from the earliest forms of mammalian life. That does not mean our current status is small mammalian rodents. Birds have reptillian ancestry, they are not currently reptiles. 204.65.34.169 (talk) 14:08, 13 January 2011 (UTC)