Talk:Dinosaur

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Is there a prejudice against the possibility of aquatic dinosaurs?

I removed the statement that no dinosaurs became aquatic. There seems to be a sort of reluctance to place them in water. This is probably because it is regarded as a retrograde condition (harking back to the image of water-bound, sluggish sauropods). Some dinosaurs may have been amphibious. There is some recent study on the possible amphibious lifestyle of diplodocids. It has been speculated that spinosaurids such as Baronyx may have hunted in rivers. And it seems unlikely that creatures that so successfully dominated every environment (save the seas, dominated by other reptiles, and the skies, dominated by pterosaurs) would not also have taken to the rivers and lakes. Elephants today display no obvious aquatic characteristics. But given the opportunity, they spend much time in water. They may have no specific adaptations to water but they have none mitigating against (observe how versatile the trunk is in varied environments. Likewise the marine iguana has no obvious adaptations to an aquatic lifestyle. That certainly doesn't stop it though! So I suggest we not appear to be dogmatic about the question.--Gazzster (talk) 00:16, 9 June 2008 (UTC)

Could we put our hands on our hearts and say no dinosaurs took to the water? It is harder to believe that none ever enjoyed water than to believe that they didn't.--Gazzster (talk) 00:38, 9 June 2008 (UTC)

Do we have a reliable source (say a peer-reviewed paper) which states any of them were aquatic? Firsfron of Ronchester 00:49, 9 June 2008 (UTC)

Do we have a reliable source to say that none were? There are however studies of diplodocids and spinosaurids that suggest some dinosaurs may have been amphibious. But I am not defending the aquatic habits of dinosaurs: I am pointing out that the statement as it stands is unjustifiably dogmatic and without a citation.--Gazzster (talk) 04:00, 9 June 2008 (UTC)

I think the larger problem is there is no evidence OF aquatic non-avian dinosaurs, and while dipodocids and other sauropods were historically believed to live in swamps, to my knowledge that has been completely discarded. IIRC some spinosaurids were thought to eat fish, but I'm unaware of anyone describing them as aquatic. Titanium Dragon (talk) 10:48, 9 July 2008 (UTC)

No prejudice, we just don't have any yet. If anything, I'd be happy to see "aerial" gone, since there's a decent chance some of the whole mishmash of almost avian nonavians were aerial. "Aquatic" may be a loaded term, though, since the real point is to distinguish them from definite marine animals like plesiosaurs, ichthyosaurs, and mosasaurs. J. Spencer (talk) 04:22, 9 June 2008 (UTC)

OK. Maybe we should use the word marine then. And add that some may have been aerial.--Gazzster (talk) 04:27, 9 June 2008 (UTC)

Or rather, none are known to have been marine creatures.--Gazzster (talk) 04:32, 9 June 2008 (UTC)

First, I agree with J. Spencer's point that we can't say there were no aerial dinosaurs - Origin of birds contains a lot of the details.

"Aquatic" is ambiguous, as it could cover anything from otters or crocs, which are physically not very different from their nearest terrestrial relatives (extinct on the case of crocs), to modern whales, which are practically helpless on land. AFAIK no fossils have been found that are clearly dinos and are at least as well adapted for swimming as they are for walking. Perhaps the article should be equally explicit - and provide a citation or two, as Gazzster suggests. Philcha (talk) 23:32, 9 June 2008 (UTC)

There are several types of aquatic and semi-aquatic dinosaurs. First, there are the birds, of which aquaticness has evolved several times (hesperornids, plotopterids, penguins, etc.), spinosaurs were predominantly coastal and shoreline hunters, eating fish, pterosaurs, and possibly preying on or scavenging small dinosaurs. There is evidence that shows that the primary prey of Ceratosaurus were fish, turtles, and crocodilians, with a lesser emphasis on dinosaurs. But the two reasons why we don't have massive whale-like radiations of dinosaurs is that one, the only major aquatic group (spinosaurs) died out in the Turonian extinction event, and two, the seas were already dominated by mosasaurs, plesiosaurs, icthyosaurs, etc.Metalraptor (talk) 17:05, 14 June 2008 (UTC)

Yes. I thinik it unlikely that most successful animals on the planet at the time did not not radiate into semi-aquatic environments also.--Gazzster (talk) 23:27, 14 June 2008 (UTC)

Well, given penguins exist, and we know they're aquatic... however, it is possible that non-avian never reverted to an aquatic lifestyle. It may be that they were too adapted to living on land, or perhaps they simply didn't have the ability to outcompete crocodiles, amphibians, and the already extant (and now long exinct) aquatic reptiles. I have my doubts that they didn't, but without evidence OF them, we can't say they existed, but I honestly don't think we should include a statement about them being aquatic or non-aquatic at all unless we've got a reliable source. Titanium Dragon (talk) 10:48, 9 July 2008 (UTC)

Fair enough.--Gazzster (talk) 23:16, 9 July 2008 (UTC)

I think there has been a prejudice against the idea of semi-aquatic dinosaurs due to the dicrediting of the once prevalent belief that sauropods needed to live in water in order to support their weight and stop their tails dragging. The rejection of this idea after it was established that dinosaur bones were hollow,has caused a backlash against semi-quaticism. However recent trackway discoveries seem to imply an ornithiscian dinosaur walking on tiptoe- i.e. partially supported by water, soperhaps we should not throw the dinosaur out with the bath water!(lol)--Streona (talk) 11:11, 20 July 2008 (UTC)

Elephants are not hairless

I want to point out that in the Dinosaur page, it contains a piece of information saying elephants are 'hairless.' In reality, they are not. Or you can check out a photo at http://picasaweb.google.com/beckydono/PaiElephantTrek/photo#5052795800087148306. The following website has an elephant's tail with hairs. http://www.globelens.com/african-elephant/ There is also a BBC News mentioning hairs of elephants. http://news.bbc.co.uk/nolpda/ukfs_news/hi/newsid_4567000/4567534.stm?REF=0

If anyone is able to edit the page, please correct the inaccurate information. Thank you. Tc03a (talk) 00:17, 14 June 2008 (UTC)

Size Picture

I think we need to change the size picture on the dinosaurs, for several reasons. One, no marginocephalian is represented, some ceratopsians got very large. Second, while I don't doubt that Lambeosaurus (although Shangtungosaurus could probably give it a run for its money) and Stegosaurus were the largest in their respective category, Amphicoelas and Spinosaurus were doubtful. Amphicoelas and the big B (I forget the name of that Indian sauropod) are known from dubious remains. Amphicoelas was named by a guy who was trying to one-up his rival, and the bone has been subsequently lost. It is very possible that he lied about its size to get one over on Marsh. As for the big B, part of its skeleton (which consists of only two bones) turned out to be a theropod. Until we get a good skeleton of it, it really can't be the biggest dinosaur. As for spinosaurus, I consider its large size dubious. Its current sixty foot size is inferred from a maxilla from Africa. Until we come up with a complete skeleton (or at least one that consists of more than fragments), it is doubtful that Spinosaurus is the biggest. I'm not doubting there could be a sixty foot long spinosaur, or a real Amphicoelas, but until we find more concrete evidence supporting them, we should add sillouhettes of the current record holders (Argentinosaurus and either Giganotosaurus or Mapusaurus).Metalraptor (talk) 17:11, 14 June 2008 (UTC)

These size comparisons are always contentious. The text does explain that Amphicoelias may have been the largest (my own belief is that it was a genuine find and Cope did not exaggerate the size of its vertebra). The artist may very well have substituted Diplodocus hallorum or Argentinosaurus in its place however. But the purpose of these comparative diagrams is not to show the biggest, or nastiest, but to give an idea of the massive sizes dinosaurs could reach. Today we find certain individual animals of a species which far exceed the average dimensions of that species. No doubt the same happened with the dinosaurs. A 120 ft Diplodocus may simply be an overgrown individual. So I suggest we treat all such comparative diagrams as suggestions, not dogmatic statements. And in the context of the text, this is what is intimated here.--Gazzster (talk) 23:13, 14 June 2008 (UTC)

Tail dragging

Correct me if I'm wrong but I think before the 1990s, it was widely believed that dinos dragged their tails. Now, we know that they use them as a counterbalance. Should this be in the article? I don't think it's there. 207.179.153.124 ([[User talk:207.179.153.124|talk]]) 14:41, 17 June 2008 (UTC)

It was noticed far before the 1990s by several scientists, but it was not generally accepted before the 70s. By the begining of the 80s it was perfectly assumed. Just compare, in youtube, the "dinosaur segment" of The animal world (directed in 1956 by Irwin Allen) with the 1985 television documentary Dinosaur!, hosted by Christopher Reeve. You'll see ;-) 343KKT Kintaro (talk) 22:12, 20 August 2008 (UTC)

Not all of the dinosaurs held their tails in the air as counterbalance. Dinosaurs such as brachiosaurus probably kept their tails pretty close to the ground, though they were probably held slightly up. It was only the dinosaurs that were often attacked or that attacked others that needed the counterbalance the most.

It would be presumptuous to suppose that dinosaurs never rested their tails on the ground.Most animals with long tails do.--Gazzster (talk) 10:03, 9 July 2008 (UTC)

Several dinosaurs simply could not have rested their tails on the ground: they would have had to have had their tails broken to accomplish this. Firsfron of Ronchester 12:49, 9 July 2008 (UTC)

Outdated Tyrannosaurus reconstruction (by Charles R. Knight), showing "tripod" pose.

The current view is that all dinos, even the huge sauropods, evolved from small, bipedal forms. For a long time bipedal dinos were reconstructed in a "kangaroo-like" posture, with their backs sloping and their tails dragging. In this posture the femurs (thigh-bones) would have been angled backwards relative to the spine, especially in the trailing leg while walking (see picture). Then it was realised that at this angle their hip joints would be near or even past the point of dislocation. So biped dinos are now restored with their spines approx horizontal. That would require a dragging tail to be bent down much more sharply than appears to be possible in most cases, and in addition having the body horizontal meant that a stiff horizontal tail was required as a counter-balance.

Even in quadrupedal dinos such as sauropods the proximal parts of the tails (closest to the body) have features that would have made that part of the tail fairly rigid — spines on the vertebrae that overlap neighboring vertebrae and / or attachments for stiff tendons that bound the vertebrae.

On the other hand ideas that Diplodocus could have defended itself by using its tail as a whip imply that a lot of the rear part of Diplodocus’ tail was pretty flexible. Exceptions like this indicate that there was too much variation for Dinosaur to accommodate, and the best place for this sort of analysis is in the articles about major clades such as Theropoda, Sauropoda, Ankylosauria, etc. -- Philcha (talk) 13:46, 9 July 2008 (UTC)

dinosaur

personally i find this section in etymology to be a little awkward and pointless (i am also unaware of the word meaning unsuccessful): "In colloquial English "dinosaur" is sometimes used to describe an obsolete or unsuccessful thing or person, despite the dinosaurs' 160 million year reign and the global abundance and diversity of their descendants, the birds. This usage became common while dinosaurs were regarded as cold-blooded and sluggish."

also, i wonder if the introduction and the first section on etymology should just be merged. they seem very similar. —Preceding unsigned comment added by Fantiquitous (talk • contribs) 01:22, 5 July 2008 (UTC)

Thermoregulation

I should like to object to the vulgar view that "cold-blooded" means sluggish in dinosaur terms. The Mesozoic era was a time when the ambient temperature was much higher than now and the oxygen content of air greater. Ectothermy may have resulted in higher body temperatures than endotherms, who may have had to regulate their temperature downwards. Heat regulation among warm blooded or endothermic animals is usually held to imply the production of inner body heat by food consumption, whereas there are other forms of heat production - such as that in bumble bees, who have a high body temperature induced by the exercise of their wings. Endothermy seems a very inefficient mechanism in the context of the Mesozoic environment, devoting 80% of food consumption to thermo-regulation instead of growth which may account for mammals relative lack of success in this period. Insulating media such as feathers and down may equally have served to preserve nocturnal core temperature in ectotherms as to imply endothermy--Streona (talk) 22:43, 17 July 2008 (UTC)

The terms "cold-blooded" and "sluggish" appear in a sentence that describes common perceptions before Ostrom and Bakker got to work. You're right to point out that ambient temperatures were higher than now and the oxygen content of air greater in the Mesozoic. But there's a set of reasons why sustained activity seems to require a fairly high and stable body temperature for vertebrates - see Physiology_of_dinosaurs#Metabolism for a more detailed explanation. Even in warm climates such as Florida or the tropics, ectothermic terrestrial vertebrates lack stamina - they can move as fast as endotherms for a few seconds, but then need a long rest. Insects are different because their small sizes give them superior power-to-weight ratios (muscle power is proportional to area, mass is proportional to volume) - but even so, bees do "warm-up" exercises before flying, especially early in the morning. And aquatic creatures are different because they are not constantly fighting gravity when they move. -- Philcha (talk) 23:08, 17 July 2008 (UTC)

But I think sometimes in editing dinosaur articles some of us tend to forget that the arguments for endothermy amount to nothing more than strong suggestions, not proof.And there is a case for ectothermy as well, as explained (but not necessarily supported) by Reese Barrick (Book of Dinosaurs, Scientific American, p.314, 2000) He also explains the case for a third possibility, mesometabolism. And then, of course, there is the possibility that metabolism varied between species, just as metabolism varies greatly amongst mammal species today. As Streona intimates, 'cold-blooded' is misleading, because ectothermy does not mean inefficiency or inactivity. And even a 'cold-blooded' giant dinosaur could sustain moderate to high levels of activity (though factors such as size and bone mass would mitigate against high levels). In moving away from the notion that dinosaurs were 'sluggish', we have conversely reinforced the idea that 'cold-bloodedness' is a deficient means of thermoregulation. That's not fair on our reptilian friends, who are very clever and efficient chaps.--Gazzster (talk) 00:20, 18 July 2008 (UTC)

Id like to object to the statement of birds and crocidilians being the only living ancestors of dinosaurs, as a New Zelander I am somewhat offended that the closest living relative the Tuatara lizard was completly overlooked —Preceding unsigned comment added by Wmagic1990 (talk • contribs) 21:47, 21 November 2008 (UTC)

No, the Tuatara is more closely related to lizards and snakes than to crocs, dinos and birds - see Tuatara#Taxonomy_and_evolution. --Philcha (talk) 22:27, 21 November 2008 (UTC)

weights are a problem

In the size section there are some, well, rather incorrect metric to US conversions:

…most often fall into the 100 to 1,000 kilogram (500 to 4,500 lb) category, whereas recent predatory carnivorans peak in the 10 to 100 kilogram (50 to 450 lb) category…

I don't know which is right, but 100 to 1,000 kg does *not* correspond to 500 to 4,500 lb (nor does 10 to 100 correspond to 40 to 450). So which is the basal number here? I presume the metric amounts, so I am going to change the lb weights to 220 to 2,200 and 22 to 220 respectively. If the pound weights are the basis here, someone will need to fix the change and correct the metric weights, but the present conversions are off by well over a factor of 2 in one direction or the other.

-Fenevad (talk) 11:35, 19 July 2008 (UTC)

Diplodocus did not have a semi-aquatic lifesyle!

I would like to point out that on one part of this talk page suggests that diplodocus had a semi-aquatic lifestyle.there would be lots of pressure on the diplodocuses lungs if it wnt in the water and would probably squashed its lungs and killed it! 5:49 pm, 19 July 2008 ([[User:Streona (talk) 17:01, 19 July 2008 (UTC)[[)

I'm not defending the idea of a semi-aquatic diplodocus, but this old objection is not as sound as it may appear. Many modern creatures have adaptations to cope with water pressure and there is no reason to suppose some dinosaurs could not have evolved similar adaptations. But there is no reason why a diplodocus would have had to submerge its whole body anyway. It may have wallowed like an elephant. There are objections to browsing sauropods on the grounds of pressure to the heart. But it is similarly counter-argued that animals such as giraffes have evolved mechanisms to overcome stress on the heart and so we might reasonably expect such in the sauropods. We talking about extinct creatures whose soft tissues have not, for the most part, been preserved.--Gazzster (talk) 20:52, 19 July 2008 (UTC)

Dinos did not diversify much in the Cretaceous

I just got notice of a new paper, Dinosaurs and the Cretaceous Terrestrial Revolution (KTR), by Graeme T. Lloyd and a cast of thousands, which argues that:

• Raw statistical data (e.g. Fastovky) shows a late-K diversification of dinos, but it's an artifact caused by sampling bias.
• Dinos did not take advantage of the new opportunities offered by the rise of angiosperms, while insects, lizards, snakes, crocs, mammals (notably placentals) and birds did. Dinos had only 2 significant diversifications in the Late Cretaceous, the initial radiations of the euhadrosaurs

and the ceratopsids.

• The KTR was a key in the origination of modern continental ecosystems, but the dinosaurs were not a part of it, and this may have doomed them.

Sounds like a revival of the old "senescence" idea, or a more sophisticated version of the old "alkaloid poisoning" idea. -- Philcha (talk) 17:37, 28 July 2008 (UTC)

I think it's too early in the game to draw too many conclusions, but it's interesting to think about. J. Spencer (talk) 23:59, 28 July 2008 (UTC)

I wouldn't take notice of anything Graeme says! Lol. No it's really good work, shame Nature and Science pasted it over, but at least its finally out now! Mark t young (talk) 00:02, 29 July 2008 (UTC)

"Nature and Science pasted it over". You mean they tried to paper over the cracks, or they missed a good opportunity to polish an interesting pepper? — Philcha (talk) 07:40, 29 July 2008 (UTC

:p passed. I always make stupid spelling mistakes like that with keyboards. Mark t young (talk) 18:30, 4 August 2008 (UTC)

Birds

This article does not metion much about dinosaur/bird relationship or the fact of including birds as a dinosaur ingeneral. Yes it does metioned birds evolved from theropod dinosaurs. And does lable birds as the only living dinosaurs. The whole thing though is that when dicussing dinosaurs in the article it metioned the origins of birds but not dicussing birds as dinosaurs or giving birds their own section in the article. I think birds should have a short article in the dinosaur page that gives a short summary of how modern day dinosaurs (birds) live and behave, with a link to the Bird article. All that is metioned on how dinosaurs are separate from birds should be eradicated and the article should be more of a possitive focus on birds being dinosaurs. Meaning that metioning dinosaur extinction is obsolite (you can metioned the K-T extinction event and the speices that died out but can not metioned that dinosaurs ingeneral are extinct). So the fossil record should change from Trassic-Cretaeous to Trassic-Resent. The Dinosaur article needs to be more bird friendly. —Preceding unsigned comment added by Westvoja (talk • contribs) 08:12, 14 August 2008 (UTC)

Dinosaur has a section Feathers and the origin of birds, which summarizes and links to the "main article" Origin of birds. "Feathers and the origin of birds" is a little brief and the content is not as how I would have written it, but these are matters of individual taste. Dinosaur is a pretty long article, and that limits the amount of detail that can be given about birds. Instead it concentrates on explaining dinos, including the group of dinos from which birds are thought to have evolved, and I think that plus the link to Origin of birds is a pretty helpful way to package the vast amount of information that has to be summarised. If you'd like to read these 2 articles, plus Cretaceous-Tertiary extinction which you also mentioned, and then suggest at this Talk page how much detail the summary versions should contain, I'm sure your suggestions would be taken seriously, and any with with editors disagree will be answered helpfully and courteously - most Wikipedia articles need feed-back from non-specialists. -- Philcha (talk) 10:35, 14 August 2008 (UTC)

Sorry Philcha, but I agree with Westvoja. In addition this paragraph should be entirely replaced : "It is also technically correct to refer to dinosaurs as a distinct group under the older Linnaean classification system, which accepts paraphyletic taxa that exclude some descendants of a single common ancestor". Why should it be entirely replaced ? BECAUSE IT'S FALSE. The Linnaean system does not accept or refuse paraphyletic or monophyletic taxa... those terms ("paraphyletic taxa", "monophyletic taxa"...) have no sens in old Linnaean classifications because in Linnaean the question itself about such concepts is not even formulated. "Technically correct" means nothing... or it even means "false". It is indeed very confusing for the reader, who should learn what's correct (phylogenetics is correct) and what's wrong (Linnaean is wrong, or being more accurate : Linnaean doesn't have an objective criterion of classification). I suggest the following lines:
"In modern popular terms the word dinosaurs still refers to a traditionnal conception of extinct giant reptiles who excluded birds from their membership. This conception is only a popular persistence of an old abandoned status of classification, the Linnaean one. Modern scientific classification methods (cladistics and phylogenetics) include birds in dinosaurs and that's why birds are dinosaurs. The popular persistence of the idea that birds are not dinosaurs is anyway inevitable in popular culture (comics, movies, fantasy novels) or in popular opinion, but is no longer accepted in systematics."
This text, or a similar expression, is what we should offer, in my opinion, to the reader. 343KKT Kintaro (talk) 21:57, 20 August 2008 (UTC)

I sympathise, since I'm currently working mainly on articles connected the Cambrian explosion. Many of the critters involved are very hard to fit into a Linnean-style classification, so cladistics and the concepts of stem and crown groups are generally more useful there. But the "taxonomy" sections of scientific articles that discuss the Early Cambrian critters in cladistic terms nevertheless generally use the Linnean species-genus-family-order-class-phylum hierarchy in their "taxoboxes". The sentence "It is also technically correct to refer to dinosaurs as a distinct group under the older Linnaean classification system, which accepts paraphyletic taxa that exclude some descendants of a single common ancestor" accurately summarises current practice, irrationally conservative though it may be. -- Philcha (talk) 22:18, 20 August 2008 (UTC)

The cambrian explosion? that's a fascinating subject, nice from you to keep the line on such interesting articles (I know I couldn't write a single word on this particular and difficult subject). But anyway in terms of systematics (in all the Wikipedias) I think we really should abandon the so called "taxoboxes", or change them by replacing the ranks hierarchy by a cladogram. When you say "current practice" you are wrong, it is the (wrong) current practice in Wikipedia to use taxoboxes with ranks in every article concerning taxons or species, but IS NOT current at all tu use them in modern systematics. Searchers don't use them and serious modern books neither. The current status of science is that cientists only investigate possible cladograms and don't take care any more about ranks. Only a few authors try to continue establishing a system of ranks, by putting (boldly!) modern monophyletical taxa into them, but such classifications are a sort of hybrid, an artificial "artifact", and don't correspond to the majority of "systematicians" (should we say "systematicists" ?). I already said in the Wikipedias where I can read and write (french, english, catalan and spanish) that we should abandon taxoboxes and use only phylogenetical cladograms (the old Linnaean taxoboxes with their ranks being shown to the reader in specialised articles where it could be clearly explained that they are abandoned). I need to be followed on that motion, followed by a majority of wikipedian authors, but for the moment it's not the case... why? your "technically correct" is still in fact a "totally wrong" sentence! Friendly : 343KKT Kintaro (talk) 00:02, 21 August 2008 (UTC)

I meant current practice in scientific journals - which Wikipedia then follows. I guess part of the problem is that the Linnean system still works quite well for modern animals, and then for fossils that are obviously closely-related to modern animals - e.g. mammoths and mastodons; or, going further back, dinosaurs and birds. The Mid Cambrian is the latest point at which there are fossils that clearly do not fit the Linnean system, but OTOH no-one seriously doubts that the very Early Cambrian helcionellids were molluscs. So there's no simple criterion for deciding at what geological time to stop using the Linnean system.

There's a further problem. It's simple enough to describe e.g. Marella as an arthropod (phylum) of an unknown class (it's almost certainly not a trilobite, chelicerate, crustacean, hexapod or myriapod), and this does not commit the author to a specific theory about its ancestry as a cladogram would.

However I think that's enough, as this Talk page is supposed to be about dinosaurs! -- Philcha (talk) 00:24, 21 August 2008 (UTC)

If you want to talk about getting rid of the taxoboxes, or replacing them with cladoboxes, you should bring it up at Wikiproject TOL. But I don't know how far you'll get, that has been tried without success many times by now. Dinoguy2 (talk) 05:46, 21 August 2008 (UTC)

Christianity

At school, they taught us dinosaurs were extinct long before there were people. Does that mean our school went against the truth, that God made animals and people in the beginning, at the same time? —Preceding unsigned comment added by 72.192.94.145 (talk) 03:31, 15 August 2008 (UTC)

No. Your school is right. Genesis says that God made different aspects of the world on different days. A "day" may be a metaphor for a much longer period. At the time it was written people had little idea of very large numbers or periods and the Earth shows innumerable evidence of being much more ancient than medieval biblical scholars estimated. If this is not so then the creator of the world would be planting false evidence and why would that be? Some 19th century Christian apologists tried to say that the Devil planted this evidence. However the geological evidence is so widespread, this would be tantamount to saying the devil had made the whole Earth- a view held by some medieval gnostics who were generally burnt as heretics. Given the extreme age of the Earth and the millions of generations involved, evolution is inevitable. This was first proposed by Muslim scholars in the 9th century.--Streona (talk) 05:48, 15 August 2008 (UTC)

I don't think so. In Genisis it said "And the evening and the morning were the sixth day" that sounds like a day to me; a twenty-four hour period. --Special:Contributions/Fwooper (talk) 23:27, 26 August 2008 (UTC)

Here's something to think about then: the sun was created on the fourth day. A day is the measure of the rotation of the earth in relation to the sun. So how can the days of creation be literal 24 hour periods before the fourth 'day'? And if we're going to use the Bible in a scientific discussion, 'to the Lord a day is a thousand years, and a thousand years a day'.And, raising a philosophical point, why should a Deity which exists outside time be limited in its actions by events in time?--Gazzster (talk) 00:20, 28 August 2008 (UTC)

God created light and dark the first day. The light wasn't necessarily the sun. —Preceding unsigned comment added by 70.184.39.134 (talk) 13:55, 17 September 2008 (UTC)

You mean the Big Bang? -- Philcha (talk) 14:03, 17 September 2008 (UTC)

Sweet mother of God, what part of allegorical is difficult to grasp? The Jews don't even take the book of Genesis literally, and they wrote the book. The entire book is an allegory meant to teach valuable lessons as well as construct a framework which served as an ideological foundation for a particular religion, Judaism. No where in the book does it suggest that every passage should be taken literally and in fact its form would lead one to believe the opposite. If one knows anything about ancient Hebrew culture or Judaism in general, he or she should know that the type of allegorical framework being used in Genesis is common. No one actually believes that there really was a prodigal son or that the three men with the talents or that the kingdom of God is 'literally' a bunch of scattered seeds, and the list goes on and on. Did Jesus ever outright say that these stories were figurative or didn't literally happen? No, it was a given. Why did he talk like this? Because it was a style of narrative teaching that was immediately familiar to his Jewish audience. Does the book of Genesis ever come outright and say that it is an allegory? No, it's a given. Stop trying to judge scientific issues through a bizarre and erroneous interpretation of Genesis. You can have faith in God or Jesus all you want, but when you put absolute faith into human interpretation (and translation, for that matter) you will always end up looking foolish. —Preceding unsigned comment added by Jdlund (talk • contribs) 01:06, 1 October 2008 (UTC)

bald statement that birds are dinosaurs?

I understand that in cladistics, birds must be considered dinosaurs. And the article correctly (at least in broad outline) describes the different senses of the word "dinosaur" later in the article. But the last sentence of the intro is, "Today there are 10,000 living species of dinosaurs that are commonly known as birds." I think this needs some qualification; cladistic definitions are not yet universally adopted, as one can see in various dictionaries. How about, "By cladistic definitions, today there are 10,000 living species..."? For comparison, our article on bacteria begins, "The Bacteria are a group of unicellular microorganisms." If cladistics were universally adopted, this sentence would be something like, "The Bacteria include all life on earth, except viruses." --Allen (talk) 20:17, 22 August 2008 (UTC)

I'd prefer "Today there are 10,000 living species of dinosaurs, the ones we know as birds." But it's no big deal any way - there are enough TV pop science programmes that say birds are dinos. Besides, the tone of WP articles is often downright sombre or even soporific, and a statement that wakes readers up is a Good Thing.

I don't think Bacteria is a good example, as AFAIK bacteria do their best to undermine the species concept by frequent horizontal gene transfer. Since it's generally accepted that eukaryotes were produced by a series of these, most importantly by endosymbiosis of an aerobic eubacterium with an anaerobic archaean, it seems the first true eukaryote had immediate ancestors that may have belonged to more than one domain. Hence the eukarote family tree resembles a braid rather than the hierarchy that cladistics assumes.

Witty comments on "horizontal gene transfer" are welcome :-) -- Philcha (talk) 20:52, 22 August 2008 (UTC)

True what you say about eukaryote evolution. Fish are another example I like to use when trying to point out how incomplete our adoption of cladistic definitions is. --Allen (talk) 21:18, 22 August 2008 (UTC)

I'm a Pisces, so I have to agree -- Philcha (talk) 22:20, 22 August 2008 (UTC)

You're a pisces? Talk about horizontal gene transfer! (Oh crap, you said witty...) --Allen (talk) 01:48, 23 August 2008 (UTC)

'What's in a name?' the saying goes. Names are simply labels. The label, in this case, 'dinosaur', is usually attached to a reptile of the Ornithischia or Saurischia. It is not usually attached the creatures we group in the Aves. That is one consideration. Let us remember also that there are a scientists, albeit in the minority, who dispute that your budgerigar is a dinosaur. Some say that the resemblances between birds and dinosaurs may represent a case of convergent evolution.They may be right. They may be wrong. The truth is that the truth is not known for a fact. The truth may never been known. Or the 'truth' once established, may be in time debunked or replaced by a more trendy theory.--Gazzster (talk) 12:47, 27 August 2008 (UTC)

Presumably birds are bird-hipped, but descended from lizard-hipped dinosaurs. This has always struck me as odd. Also that if birds diverged from dinosaurs in the Jurassic (Archaeopteryx) they did not therefore descend from Cretaceous raptors.--Streona (talk) 14:18, 27 August 2008 (UTC)

Yes, the hip-thing is a problem.--Gazzster (talk) 00:23, 28 August 2008 (UTC)

The hip thing is an adaptation to herbivory/omnivory, and doesn't have much to do with classification. It evolved several different times among dinosaurs. It shouldn't be "bird-hipped" as much as "herbivore-hipped." The arrangement allows for a longer digestive system. The ancestors of birds (and dromaeosaurs?) appear to have been at least partly herbivorous (troodonts, oviraptorosaurs, and therizinosaurs are all at least omnivores. Since only dromies are the odd man out, they may have re-evolved pure carnivory).

And no, of course they didn't descend from Cretaceous raptors. They descended from Jurassic raptors, which everybody seems to forget about... there are "raptors" from the same time as and before Archaeopteryx. Troodonts lived in the late Jurassic (Koparion, "Lori", possibly Jinfengopteryx). Scansoriopterygids and Pedopenna (ancestral to raptors) lived before Archaeopteryx. Teeth that appear to come from true dromaeosaurs are found in the Middle Jurassic. Palaeopteryx from the Morrison formation may be a dromaeosaurid. Dinoguy2 (talk) 01:28, 28 August 2008 (UTC)

And there's the enigmatic Protoavis to fall back on, even though Chatterjee and everyone else seems to have distanced himself from making it a bird. Doesn't look much like a bird to me. We may never know the answer. Dromaeosaurs? Archosaurimorphs? I like mystery. It may be the ancestor is still nicely snugged up in its chunk of rock, waiting to be discovered. And it may be something utterly unexpected. I mean, who would have thought Scutosaurus was related to a turtle, as is speculated? --Gazzster (talk) 07:00, 3 September 2008 (UTC)

Odd bird statement

"Today there are 10,000 living species of dinosaurs that are commonly known as birds." - This seems a bit dubious... birds aren't dinosaurs any more than humans are small shrewlike creatures from which mammals evolved. 81.157.243.185 (talk) 10:24, 26 August 2008 (UTC)

There are a few ways of classifying organisms. The oldest one still in use, devised by Linnaeus, regards dinos as reptiles and birds as something else, namely birds. But Linnaeus' system was produced before scientists knew about evolution, and does not handle extinct organisms very well. The classification system most used in studies of evolution and of extinct creatures is cladistics, which tries to draw up a "family tree" of organisms. Under this scheme, birds are dinosaurs since they evolved from one group of dinos; and if you trace back through the family tree you'll see that birds and dinos are archosaurs, diapsids, amniotes, tetrapods, fish(!!), chordates, deuterostomes, bilaterians, metazoa and eucaryotes. Likewise humans are primates, mammals, therapsids, synapsids, amniotes (this group contains the last common ancestor of all mammals and all dinos), tetrapods, fish(!!), chordates, deuterostomes, bilaterians, metazoa and eucaryotes. -- Philcha (talk) 10:56, 26 August 2008 (UTC)

I do agree, though, there is one very dubious notion, namely Using the strict cladistical definition that all descendants of a single common ancestor must be included in a group for that group to be natural, birds are dinosaurs and dinosaurs are, therefore, not extinct. - this would make all land-living vertebrates fish! Grouping birds into the dinosaur taxon is either a misintepretation of that statement (as it would prevent introduction of ANY new taxon during the course of evolution) or inconsequential 90.134.120.187 (talk) 12:39, 10 October 2008 (UTC) (btw. that identification won't help you recognize me as my IP changes every 24 hours. But I'm too lazy to create an account)

I just said that birds are dinos, archosaurs, ..., and eucaryotes; and we are fish, and chordates, ..., and eucaryotes. This does not prevent the introduction of new taxa, for example if ET biologists tracked the course of evolution on this planet they'd have seen the appearance of and defined new taxa for fish, tetrapods, amniotes, ..., and humans - but the new taxa would be contained within the existing oes, like Russian dolls. Right now I don't know how many new insect species are discovered per year, and new taxa are defined for them (more Russian dolls). Grouping birds into the dinosaur taxon is not inconsequential, as it implies that dinos are not extinct, and that at one time there must have been a few birds that were very like non-bird theropods and a few non-bird theropods that were very like birds. This has a lot of implications, e.g.: dinos are not one monolithic lump but varied a lot, both over time and at any one time between about 190 million years ago and 65 million years ago, and the survivors (birds) have diversified very successfully since then; since birds are warm-blooded, there's a big debate about whether any non-bird dinos were warm-blooded. -- Philcha (talk) 13:10, 10 October 2008 (UTC)

"Birds are dinosaurs"??? You must be bloody kidding me. I won't get drawn into an argument over claudistics or the strict scientific justification, or how it is like saying "Man" is an "Ape" (although sometimes I wonder.) Let me just say it's statements like this that make WP look silly and unprofessional to the average reader. JQ (talk) 02:37, 6 March 2009 (UTC)

Thanks for your suggestions. We'll refrain from including the opinions of professionals next time. Dinoguy2 (talk) 03:26, 6 March 2009 (UTC)

You have it backwards, JQ. Saying birds are dinosaurs is as professional as it gets. Go ahead, ask a professional. The only people (well, almost) who wouldn't say that birds are dinosaurs are laymen (non-professionals). So actually, saying that birds AREN'T dinosaurs would be the unprofessional way to go. Sheep81 (talk) 05:52, 6 March 2009 (UTC)

Attempts to recreate dinosaurs

Why is there no mention of scientists trying to recreate dinosaurs? There have been numerous attemps by scientists, yet I have found no mention of this on Wikipedia at all. Attempts include creating dinosaurs from DNA taken from ancient mosquitoes frozen in amber (which inspired Jurassic Park) (disproven when the DNA samples were discovered to have been contaminated milions of years ago), creating them from stem cells that survived million of years (disproven when realize they would never be capable of finding the number of stem cells needed), or retro-engineering birds to give them dinosaur-like characteristics (it has been proven that this is possible through experiments with mutliple animals species, such as flies an rabbits). 174.130.12.126 (talk) 22:01, 7 September 2008 (UTC)

Because none of those things ever happened? There have been no serious, credible attempts to recreate dinosaurs. What you list is a series of media misrepresentations and misinterpretations of actual work that never had such a silly purpose. To quote a blog I read, recreating a dinosaur is like "trying to knit a Lambourgini out of steel wool". Mokele (talk) 22:33, 7 September 2008 (UTC)

What's missing from the article is an account of earlier attempts to amplify dino DNA, mostly for taxonomic purposes, and the debunking of this possibility by Cooper and colleagues. This may or may not be a reasonable starting point (don't have journal access from this computer). (Iirc Cooper and colleagues concluded that anything older than 100,000 years was definitely beyond recovery. That may or may not be the latest news in that debate.) Papa Lima Whiskey (talk) 11:46, 12 September 2008 (UTC)

To even consider such a thing is just a freak show.--Streona (talk) 17:17, 22 September 2008 (UTC)

Somebody watched Jurassic Park way too many times. —Preceding unsigned comment added by Jdlund (talk • contribs) 01:09, 1 October 2008 (UTC)

you know some one should put that we might be able to really clone dinosaurs by taking a large or medium-sized bird and go backward, by giving it a tail, teeth, arms, ahdns and fingers and making a dinosaur from that, does the show "Dinosaurs: Return to Life" ring a bell —Preceding unsigned comment added by Aslan10000 (talk • contribs) 02:34, 17 December 2008 (UTC)

Why Triceratops?

Under 'modern definition', it says "Under phylogenetic taxonomy, dinosaurs are usually defined as all descendants of the most recent common ancestor of Triceratops and modern birds." Why Triceratops in particular? It would be nice to explain this better. The cited source doesn't explain, unless I'm missing something.The Drama Llama (talk) 20:16, 11 September 2008 (UTC)

Any ornithischian dino would do, it's just that Triceratops is the most charismatic and one of the easier ones to spell. That answer may look flippant, but it's pure plain truth. -- Philcha (talk) 20:37, 11 September 2008 (UTC)

So... is this some kind of 'official' definition or not? The whole thing seems odd to me (as a non-expert) and could do with clarifying.The Drama Llama (talk) 22:36, 11 September 2008 (UTC)

It's all to do with cladistics. A monophyletic clade (group) is all the descendants of a single commom ancestor, plus that common ancestor. The definition "dinosaurs are usually defined as all descendants of the most recent common ancestor of Triceratops and modern birds" assumes that: dinos are a monophyletic clade; all the descendants of their last common ancestor are either saurischians or ornithischians (this is the dubious assumption, IMO, as there are several "basal" dino genera, e.g. Staurikosaurus, Hererrasaurus); Triceratops is the last member of its branch of the ornithischian lineage (reasonable); birds are the last members of the saurischian lineage (almost certainly). But "... of the most recent common ancestor of Tyrannosaurus and Edmontosaurus" would also be good enough, as these are/ were the last members of their branches of the saurischian and ornithischian lineages respectively. You'll see what I mean if you have a look at Dinosaur#Classification and see what these two possible definitions include - they're equivalent. Philcha (talk) 23:14, 11 September 2008 (UTC)

PS my flippant comment above was too flippant in one respect - only the latest member of any group of ornithischians would do. So for example Triceratops is a good choice for ceratopsians but e.g. Protoceratops would be a poor choice as it may be the ancestor of many later ceratopsians, which would be excluded if the definition used Protoceratops for the ornithischian lineage. -- Philcha (talk) 23:20, 11 September 2008 (UTC)

That's not really correct--assuming the basic split between saurischians and ornithischains is right, literally any ornithischian of fairly certain classification would do fine. Protoceratops, Hypsilophodon, etc. A competing defintion uses Megalosaurus and Iguanodon, the first ornithischian and saurischian described. Whether basing the definition on latest-surviving (Triceratops, Passer), historical, etc. is a matter of taste only. Actually, the PhyloCode has a provision stating original intent trumps other definitions, so Iguanodon+Megalosaurus (maybe also + Hylaeosaurus) will probably become the official definition when that goes into effect in a few years. Dinoguy2 (talk) 00:28, 12 September 2008 (UTC)

Stygimoloch ?--Streona (talk) 23:29, 11 September 2008 (UTC)

OK, that makes sense and thanks for explaining. But wouldn't it be better to say something like "dinosaurs are usually defined as all descendants of the most recent common ancestor of the last ornithischians and modern birds"? It seems less random, and easier to understand for the layman, as it otherwise risks suggesting that Triceratopses are somehow special.The Drama Llama (talk) 00:25, 12 September 2008 (UTC)

That's not a bad idea, and actually I'd make it "ornithischians and saurischians (including birds), specified in official definitions by representative embers of each group, for example Triceratops + ..." etc. etc. Dinoguy2 (talk) 00:37, 12 September 2008 (UTC)

Species counts

I'm not sure whether this material would belong here, or in Dinosaur classification, so raising it for a decision by those more knowledgable of how Wikipedia is covering the topic. This BBC News/Science article discusses an article in the journal Biology Letters that is on the accuracy of species counts and number of species. There is apparently (see paragraph 2) a controversy in the field about the number of species and the degree to which modern "new species" are truly newly discovered versus new names for old species. It does say that there have been 1,047 names given for dinosaur species from 1824 to the present, duplication has reduced the number to 500 or so now considered species, and that new species are currently being described about once a fortnight. All of this looks like material that Wikipedia ought to cover - but where, and can someone with access to the relevant journals (not me) use them as sources? GRBerry 14:44, 17 September 2008 (UTC)

I'm guessing they're taling about the new Benton paper? It's available free here: [1] currently first line under 2008. Dinoguy2 (talk) 01:03, 18 September 2008 (UTC)

The BBC article does focus on that paper, yes. But I wouldn't want to add here without at least reading the other papers on error rates with which Benton is disagreeing. And where should it go? GRBerry 02:44, 18 September 2008 (UTC)

dinosaurs are cool —Preceding unsigned comment added by Shaneh16 (talk • contribs) 11:06, 18 September 2008 (UTC)

I had found the BBC article on my own and added it to the article before I read the talk page. I'll trust the editors here to keep or remove it. Grundle2600 (talk) 16:59, 18 September 2008 (UTC)

Air sacs, etc.

Well done for finding the Areosteon article, User:Craigsjones!

I think some re-structuring is in order. Dinosaur now has related material in sections "Physiology" and "Feathers and the origin of birds:Soft anatomy" (which follows but should support the metabolic stuff in "Physiology"). "Physiology" deals only with metabolism but is rather long. I therefore suggest:

• Feathers (w/o birds)
• A single section "Physiology" structured something like Physiology of dinosaurs, with metabolism the last sub-section as it uses many of the others.
• Origin of birds, which will use previous material relating to feathers and physiology.
• If any of these sections / sub-sections looks too long, move excess material to Physiology of dinosaurs if it's not already covered there. -- Philcha (talk) 07:52, 30 September 2008 (UTC)

interwiki link

Please Add Inter wiki link to telugu article te:డైనోసార్. Thanks

రవిచంద్ర (talk) 04:42, 8 October 2008 (UTC)

 Done OhNoitsJamie ^Talk 04:49, 8 October 2008 (UTC)

Recommended New External Link for this article

Dear Editors I would like to suggest a new link to add to the external links section of this article: “Dinosaur Central” [2] This is a high quality, comprehensive site covering many areas of dinosaur interest. It’s free content includes a searchable database, dinosaur movie guide, downloadable images, dinosaur drawing guide, new species list, dinosaur video portal, special creature spotlight, dinosaur news and a weekly history section.

Kind Regards A fellow dinosaur enthusiast --Cleoandsesha (talk) 11:32, 24 October 2008 (UTC)

I have reservations about this, first and foremost because the site appears to use a number of images without giving credit or in violation of their Creative Commons licenses, many of them by our own editors. This page, for example [3], uses a number of AW's illustrations with no credit or link to the CC page, in clear violation of the license. I don't think we should condone this type of infringement by giving a link. Dinoguy2 (talk) 06:33, 25 October 2008 (UTC)

Update--I've just been in contact with the author of this site, and he does have permission from all featured artists to use their images, I assume waving the requirements of CC (which requires the license to be cited each time an image is reproduced). So, unless the commercial areas of the site are an issue, I don't see a problem with including a link. Dinoguy2 (talk) 02:12, 26 October 2008 (UTC)

interwiki FA

Someone should add the Link FA|ca , thanks--Ssola (talk) 22:17, 27 October 2008 (UTC)

Done. Congratulations! J. Spencer (talk) 22:50, 27 October 2008 (UTC)

A few edits to the intro

I've made a few changes to the intro paragraphs, mostly to address some flow and word choice issues. Cheers, Killdevil (talk) 23:00, 5 November 2008 (UTC)

In this edit the change from "Most research ... has supported the view that dinosaurs were active animals with elevated metabolisms".. " to "Nearly all ..." is an exaggeration. The previous "since the 1970s" was also more future-proof than "in the last 40 years". --Philcha (talk) 23:01, 5 November 2008 (UTC)

Hmm, OK -- I just revised things a bit to address your comments. Killdevil (talk) 03:20, 6 November 2008 (UTC)

Some edits to the "Cultural Depictions" section

I've made some changes to the "Cultural Depictions" section. Cheers, Killdevil (talk) 00:51, 21 November 2008 (UTC)

Cool. Feel free to borrow from the main article, 'cause it's a GA now. J. Spencer (talk) 02:56, 21 November 2008 (UTC)

Failure to adapt to changing conditions?

We now have a subchapter with this content:

Lloyd et al (2008) noted that, in the Mid Cretaceous, the flowering angiosperm plants became a major part of terrestrial ecosystemss, which had previously been dominated by gymnosperms such as conifers. Dinosaur coprolites — fossilized dung — indicate that, while some ate angiosperms, most herbivorous dinosaurs mainly ate gymnosperms. Statistical analysis by Lloyd et al concluded that, contrary to earlier studies, dinosaurs did not diversify very much in the Late Cretaceous. Lloyd et al suggested that dinosaurs' failure to diversify as ecosystems were changing doomed them to extinction.

However, the study in question concluded that there was no proof of any progressive decline at the end of the Cretaceous. True, the paper ended — and this was the only sentence which might be construed to entail the suggestion mentioned in the subchapter — with the ominous words Hadrosaurs and ceratopsians showed late diversifications, but not enough to save the dinosaur dynasty from its fate., but pointing out the obvious fact that any adaptation to the eating of angiosperms was not enough to ensure the continued existence of most dinosaur clades in the face of, e.g., a giant bolide impact should not be taken as implying that a lack of it somehow was a major cause of their extinction; after all the paper states: The patterns of rises and falls in the diversity of Cretaceous dinosaurs and Cretaceous plants, as well as their palaeogeographic distributions, do not suggest any correlation.--MWAK (talk) 18:26, 4 December 2008 (UTC)

Birds and Time Periods

I, like all of you, want to improve this article and I say we should remove the parts of dinos-birds and the time periods. Due to us not knowing the exact time we should not tell the reader the age but the general information. I also say this because of cryptozoology.69.23.218.70 (talk) 01:46, 18 December 2008 (UTC)

Well, if you have some reliable sources that verify what you state here, please go for it. And Cryptozoology is a fringe theory, and we cannot give undue weight to such theories. OrangeMarlin ^{Talk• Contributions} 01:49, 18 December 2008 (UTC)

If one wants to improve the article, one should not replace science by pseudo-science.--MWAK (talk) 10:57, 29 December 2008 (UTC)

In Question

The article says "Under phylogenetic taxonomy, dinosaurs are usually defined as all descendants of the most recent common ancestor of Triceratops and modern birds.It has also been suggested that Dinosauria be defined as all of the descendants of the most recent common ancestor of Megalosaurus and Iguanodon, because these were two of the three genera cited by Richard Owen when he recognized the Dinosauria." What are all the other species recognized nowadays as dinosaurs, then? What about the sauropods and the non-maniraptorian or allosaurian theropods, the ankylosaurians, stegosaurians, and non-iguanodontian ornithopods? They aren't descendants of Triceratops or birds or Iguanodon or Megalosaurus. That kinda needs revision, 'cause it's contradicted by the following statement: "Both definitions result in the same set of animals being defined as dinosaurs, including theropods (mostly bipedal carnivores), sauropodomorphs (mostly large herbivorous quadrupeds with long necks and tails), ankylosaurians (armored herbivorous quadrupeds), stegosaurians (plated herbivorous quadrupeds), ceratopsians (herbivorous quadrupeds with horns and frills), and ornithopods (bipedal or quadrupedal herbivores including "duck-bills")." —Preceding unsigned comment added by 142.26.133.248 (talk) 18:33, 5 January 2009 (UTC)

"Descendants of the most recent common ancestor of" is the key phrase here. The most recent ancestor held in common by a Triceratops and a turkey, or a Megalosaurus and an Iguanodon, is also the ancestor of those other dinosaurs. If the chosen animals were a Deinonychus and a Velociraptor, you'd get a much smaller set, because the most recent common ancestor of those two is not the ancestor of any dinosaur outside of some dromaeosaurids. If the chosen animals were Triceratops and Tanystropheus, the most recent common ancestor of those two would also have led to crocodilians, phytosaurs, aetosaurs, and a bunch of other things. J. Spencer (talk) 22:57, 5 January 2009 (UTC)

More finicky - should it not be "the most recent common ancestor of Triceratops and modern birds, and all its descendants", i.e. the LCA must also be a dino? Otherwise I think the definition would allow polyphyletic dinos if one offspring of the LCA was the first saurischian and another was the first ornithischian. --Philcha (talk) 23:16, 5 January 2009 (UTC)

For some reason I found that hilarious, even though it is true by definition that the first generation after the LCA has to include the first saurischian and the first ornithischian. J. Spencer (talk) 02:23, 6 January 2009 (UTC)

At any rate, it was a good catch, because the citation didn't cover the material cited. J. Spencer (talk) 02:34, 6 January 2009 (UTC)

Could you please explain to me my unintended joke? :-)

While looking unsuccessfully for the joke myself, I was reminded of why I'm not keen on phylogentic definitions. For example the definition given does not allow for a third lineage descended from the LCA (possibly just "other basal dinos"), nor for multiple "generations" (e.g. chronospecies) of clearly basal dinos before the saurischians and ornithischians diverged. --Philcha (talk) 11:18, 6 January 2009 (UTC)

The funny wasn't all that funny, just something in the way I was thinking about the first saurischian and the first ornithischian. It's like the parents looking at the hatching eggs and saying, "Okay, you are the ornithischian, and you are the saurischian." J. Spencer (talk) 01:16, 7 January 2009 (UTC)

That's just the way the definition was set up: as a node/stem triplet. All dinosaurs must either be a saurischian or ornithischian. Anything that isn't, isn't a dinosaur. That was done to preserve traditional content. All those links leading up to the split are covered under Dinosauriformes (lagosuchians, silesaurs, etc.). By "clearly basal dino" you're using a morphological, not phylogenetic definition. In cladistic terms, any series of chronospecies leading up to the split will clearly be non-dinos. (Or, depending on how you define species, would all be the LCA and so be included). Of course, you could always define dinosaurs as a stem, rather than a node (say, all species closer to Megalosaurus than to Lagosuchus), which would include many species before the saur-ornith split. Either way is arbitrary, but one way guarantees you get all the traditional dinosaurs, while with the other, there's always a slim chance ornithischians could turn out to be non-dinosaurian. As it stands, there's a very slim chance sauropods could be non-dinosaurs, since they're not named in the node definition, but they were originally considered crocodiles anyway ;) Dinoguy2 (talk) 22:59, 6 January 2009 (UTC)

"Etymology: Really?" or "Yumm, That New OR Smell!"

Ok, currently in the Etymology section, there is an unsourced statement that has the suspicious stink of OR (very light on the "R" no doubt), which claims that the colloquial use of the word "dinosaur" to describe "an obsolete or unsuccessful thing or person" (this phrase is sourced to Mirriam-Webster, which does not mention the following) "became common while dinosaurs were regarded as cold-blooded and sluggish." While no doubt literally true, the implication is that the reason "dinosaur" denotes something obsolete or unsuccessful is because they were thought to be sluggish. It seems to me, however, highly more likely that, although dinosaurs were wildly successful in their day, we've come to use the word to mean "obsolete or unsuccessful" merely because dinosaurs are by far the most famous group of animals that have gone extinct (there it may be relevant to note that this use probably began before we knew that birds are dinosaurs). The word "obsolete" here rings the Obvious Bell especially loudly -- what does "obsolete" have to do with being sluggish or cold-blooded? It may be that our notion of the word dinosaur in this usage is informed by both explanations. Certainly one may describe an old codger, to whom it would be appropriate (though inconsiderate) to apply the term, as both "old" and "dying out" as it were, as well as "cold-blooded" and "sluggish". Certainly some overlap there. While I would like to rewrite this little sentence (doing so would have been a lot easier than all this), I'd be remiss if I wiped someone else's OR only to substitute my own, and right now I don't have access to any kind of etymological dictionary, much less one that would have good research on a modern colloquial usage like the one in question. So... anyone? —Preceding unsigned comment added by Torgo (talk • contribs) 16:51, 3 January 2009 (UTC)

I removed the commentary, as I have no idea when or how the secondary usage came into being. I suspect it's probably more due to their being dead, though. J. Spencer (talk) 19:30, 3 January 2009 (UTC)

Proof?

Where is the evidence concerning the point that dinosaurs lived over 65 million years ago? This is not proven, and should not be in the article unless there is hard evidence regarding it. —Preceding unsigned comment added by 86.155.202.11 (talk) 18:46, 3 January 2009 (UTC)

Yeah, I agree. How can anyone really KNOW about things that happened before people existed? And don't give me all that carboxic dating stuff. It's never been proven to work. People just love to try and tear down other people's beliefs. Hey geniuses, God was there. HE did it, HE would know. 161.130.178.151 (talk) 23:58, 22 January 2009 (UTC)

It would be slightly easier to take you seriously if you did enough research to know a) the name of the dating system that you're attacking (I assume you're referring to carbon dating, as there is no such thing as carboxic dating) and b) that carbon dating is not used with dinosaurs, as its half-life is far too short. The age of dinosaur-bearing rock formations are typically dated via a combination of uranium-lead and argon-argon systems for absolute dates of igneous rocks found above or below the fossil-bearing sedimentary rocks (typically ash beds and thin volcanic basalt flows), and marine invertebrate fossil correlations and paleomagnetic chronology for relative dating. Additionally, this article is about dinosaurs, whereas your issues are apparently not about dinosaurs, but nuclear physics and radioactive decay, basic laws of geology, and a god who apparently decided to fake an internally consistent old earth, so I'd recommend raising your questions at those articles instead. J. Spencer (talk) 00:46, 23 January 2009 (UTC)

Dinosaur Extinction Causes

As of December 2008, the major differences of professional opinion on the causes of the mass extinctions continue to be between the supporters of the Chicxulub Impact event and those of the Deccan Traps volcanism.

The dispute over the causes of the extinction at the end of the Cretaceous has again come to the fore after the December 2008 meeting of the American Geophysical Union in San Francisco.

There, Gerta Keller of Princeton University emphatically repeated her remarks of 2003. Additional field-work by Keller and her colleagues supports the conclusion that the extinctions happened at the same time as the end of the main phase of India's Deccan eruptions, which points to it being volcanism that killed the dinosaurs.

Keller states: "The Chicxulub impact hit the Yucatan about 300,000 years before the mass extinction that included the dinosaurs and, therefore, could not have caused it." Keller also said that the Chicxsulub crater has been vastly overestimated as evidence. More information on these findings will be released later in 2009.

Contacted after those assertions were made, Walter Alvarez continues to reject the idea of volcanism as the cause of the mass extinctions, saying that other scientists have also, after detailed examination, found it unacceptable and that few experts would agree that Chicxulub is older than the extinctions. As a reminder, he said that it was the discovery of the thin layers of iridium, rare at the earth’s crust but more abundant in meteorites, that triggered his impact theory. And subsequently, around the world, similar debris from a giant impact was identified in sediments deposited at the same time as the mass extinction happened. Alvarez said that volcanism may have played a contributing role but that the Chicxsulub event was the primary trigger.

So where does that leave us? It is well known that many times in the past the Earth has suffered major consequences from the impacts of asteroids and comets that have reached Earth from far out in the Solar System.

I have not heard it expressed elsewhere, but it occurs to me to ask: could Walter Alvarez have located the wrong crater, a crater 300,000 years too old? And is it possible that the real culprit, if it was a meteorite, is still waiting to be found? The combination of the evidence of the Deccan Traps volcanism together with a new discovery of a younger dated catastrophic impact would seem to be the best of both worlds and might even satisfy both camps.

About the object that impacted at Chicxulub, the bolide, scientist David Brez Carlisle, in his book “Dinosaurs, Diamonds and Things from Outer Space” published in 1995 by Stanford University Press, states that the impactor was not an asteroid but a comet of about 20 miles in diameter. This interpretation being based, among other things, on the composition of the non-terrestrial rock materials at the crater site. He provides several pages of valid scientific details to support his conclusion.

Rezansoff (talk) 19:06, 24 January 2009 (UTC)

Intro

I've played about with the intro slightly. I think the bird discussion, whilst important, seems a bit of a digression coming as it does in the second paragraph. There should be a more general discussion of what dinosaurs were before this talk of their ancestry. As this is a featured article I've attempted to rearrange rather than rewrite too much. Pretty Green (talk) 09:03, 9 February 2009 (UTC)

I was thinking of making this change myself. Good stuff. While we're talking about the intro, does anyone share my sense that it could benefit from a sentence or two addressing the physical characteristics of dinosaurs? We say near the beginnning that they were the dominant vertebrate animals of terrestrial ecosystems, we say they were active and warm-blooded, and down below we compare them with birds, crocodilians, and other archosaurs... but I'm not sure that's enough. Killdevil (talk) 21:36, 10 February 2009 (UTC)

I think a more general overview of characteristics in the intro, removing something from the birds/crocodiles/archosaurs bit if necessary would improve how this reads. --Pretty Green (talk) 09:28, 11 February 2009 (UTC)