# What is--and isn't--a dinosaur? **URL:** \ **Category:** Factual Questions\ **Created:** [January 19, 2019, 4:00am UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027 "2019-01-19T04:00:42Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [January 21, 2019, 1:29am UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/21 "2019-01-21T01:29:03Z")
> [@Darren\_Garrison](#): > > No. No “error” was made–he correctly grouped them together because all three groups shared the derived characteristic (the term modern, not his) of five fused vertebrae in the sacrum. See [this](https://blog.biodiversitylibrary.org/2015/10/the-birth-of-dinosaurs-richard-owen-and-dinosauria.html), [this](http://www.miketaylor.org.uk/dino/faq/s-class/whatis/index.html), and for an illustration [this](https://svpow.com/2008/03/24/your-sacrum-is-negligible/). > > Also, no credible paleontoligist denies the dinosaur origin of birds–that is nutbag flat-earther territory. Yes, but Dinosauria are not reptiles and Owen had no idea that Birds were Dinosauria. No, it’s not nutbag stuff. Honestly there are reputable scientist who argue that altho Aves and Dinosauria have a common ancestor, they split off before. > **[Longisquama](https://en.wikipedia.org/wiki/Longisquama)** > > html.skin-theme-clientpref-night .mw-parser-output .infobox.biota tr{background:transparent!important}html.skin-theme-clientpref-night .mw-parser-output .infobox.biota img{background:white}@media(prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .infobox.biota tr{background:transparent!important}html.skin-theme-clientpref-os .mw-parser-output .infobox.biota img{background:white}} > Longisquama is a genus of extinct reptile. There is only one species, Longisquama insignis, ... Background Main articles: feathered dinosaurs and origin of bird flight - A minority of scientists prefer the hypothesis that birds evolved from small, arboreal archosaurs like Longisquama. They see these as ectothermic animals that adapted to gliding by developing elongated scales and then pennaceous feathers. This hypothesis, however, is not supported by cladistic analysis.\* [https://answers.yahoo.com/question/index?qid=20140525120521AAVvzTQ](https://answers.yahoo.com/question/index?qid=20140525120521AAVvzTQ) \*There is no consensus. Most paleontologists are cladists, and practically all cladists believe that birds evolved from a dinosaur. There are also many biologists who have not kept up with the latest research on bird origins, and they were taught as undergraduates that birds evolved from a dinosaur similar to Deinonychus if they received their university education since the late 1960s. These 2 groups add up to over 50% of scientists. Starting in the mid-1990s, however, more and more scientists now doubt that birds evolved from a dinosaur. It started with developmental evidence by scientists such as Richard Hinchliffe, who found that birds most likely had fingers 2-3-4 but fossil evidence strongly suggests that theropod dinosaurs have fingers 1-2-3. Then scientists like John Ruben, Alan Feduccia, and Larry Martin did research that show that the taxonomic characters uniting theropod dinosaurs and birds are extremely unlikely to be homologous, suggesting instead that they are only superficially similar. Then, in 2000, a paper based on the re-examination of the fossil Longisquama, which was part of the group of fossils being brought to the USA from Russia, shows that it has feathers that were likely homologous with those of birds. Since Longisquama is not a dinosaur by any stretch of the definition or the imagination, it dealt a severe blow to the view that birds evolved from a dinosaur. Knowing that Longisquama feathers would deal their cladistic religion and their careers a severe blow, because they would have to admit that cladistic analysis failed time after time to come up with the correct answer about the real ancestor of birds, some paleontologists tried to bury the facts. … That is not all, the cladists are spending time courting the popular press and ignorant journalists to continue propping up the theory that birds evolved from a dinosaur. The facts simply do not support the dinosaurian origin of birds, because there is no known fossil that has the features of Deinonychus and that lived in a period of time before the oldest known birds. …Of course, cladists once again deny this piece of evidence, as they had done to all other pieces of evidence that contradict the dinosaurian origin of birds. So, in short, if a paleontologist’s career or career opportunity is dependent on adhering to the largely refuted dinosaurian origin of birds, then he/she probably has little choice but to keep on pretending that birds evolved from a dinosaur and bury both the facts and his/her own integrity. OTOH, scientists who are interested solely in a better understanding of nature are joining the small but growing number of real scientists who have abandoned the dinosaurian origin of birds.\* > **[Study challenges bird-from-dinosaur theory of evolution - was it the other...](https://today.oregonstate.edu/archives/2010/feb/study-challenges-bird-dinosaur-theory-evolution-%E2%80%93-was-it-other-way-around)** > > CORVALLIS, Ore. - A new study just published in the Proceedings of the National Academy of Sciences provides yet more evidence that birds did not descend from ground-dwelling theropod dinosaurs, experts say, and continues to challenge decades of... \*CORVALLIS, Ore. - A new study just published in the Proceedings of the National Academy of Sciences provides yet more evidence that birds did not descend from ground-dwelling theropod dinosaurs, experts say, and continues to challenge decades of accepted theories about the evolution of flight. A new analysis was done of an unusual fossil specimen discovered in 2003 called “microraptor,” in which three-dimensional models were used to study its possible flight potential, and it concluded this small, feathered species must have been a “glider” that came down from trees. The research is well done and consistent with a string of studies in recent years that pose increasing challenge to the birds-from-dinosaurs theory, said John Ruben, a professor of zoology at Oregon State University who authored a commentary in PNAS on the new research. The weight of the evidence is now suggesting that not only did birds not descend from dinosaurs, Ruben said, but that some species now believed to be dinosaurs may have descended from birds.\* > **[Origin of Birds: The Final Solution?1](https://academic.oup.com/icb/article/40/4/504/101454)** > > Abstract. The origin of birds has been discussed since the discovery and description of Archaeopteryx in Bavaria in 1861. By 1868, Thomas Henry Huxley real [https://onlinelibrary.wiley.com/doi/abs/10.1002/jmor.10382](https://onlinelibrary.wiley.com/doi/abs/10.1002/jmor.10382) [http://archive.news.ku.edu/2000/00N/JuneNews/June23/dino.html](http://archive.news.ku.edu/2000/00N/JuneNews/June23/dino.html) Those guys are not, in “nutbag flat-earther territory”. They are experts- which you are not. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [January 21, 2019, 1:31am UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/22 "2019-01-21T01:31:38Z")
And in one of those odd coincidences, I see that [the latest post at SV-POW!](https://svpow.com/2019/01/18/did-dinosaurs-have-a-second-brain-to-run-their-back-ends/) (which I linked earlier) readdresses the sacral brain thing. ---
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [January 21, 2019, 1:47am UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/23 "2019-01-21T01:47:10Z")
This article does a great job debunking the “Birds Are Not Dinosaurs” movement. > **[The "Birds Are Not Dinosaurs" Movement](https://blogs.scientificamerican.com/tetrapod-zoology/the-birds-are-not-dinosaurs-movement/)** > > Birds are dinosaurs. But some scientists argue that this just can’t be so because... because... well, it just can’t. What, specifically, are their arguments? ---
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [January 21, 2019, 1:51am UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/24 "2019-01-21T01:51:06Z")
Also, from your first link: “A minority of scientists prefer the hypothesis that birds evolved from small, arboreal archosaurs like Longisquama. They see these as ectothermic animals that adapted to gliding by developing elongated scales and then pennaceous feathers. This hypothesis, however, is not supported by cladistic analysis.” Not supported by evidence… Your second link goes to Yahoo Answers so forgive me if I don’t take it seriously. ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [January 21, 2019, 1:56am UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/25 "2019-01-21T01:56:08Z")
> [@Babale](#): > > This article does a great job debunking the “Birds Are Not Dinosaurs” movement. > > [The "Birds Are Not Dinosaurs" Movement | Scientific American](https://blogs.scientificamerican.com/tetrapod-zoology/the-birds-are-not-dinosaurs-movement/) Yes. Absolutely the mainstream argument hinges entirely upon cladistics and by their arguments Aves are part of Dinosauria. They have solid arguments. However, since this is \*science \*and not name calling on a playground, the contrary is not considered “nutbag flat-earthers”. Real scientists can post conflicting papers and argue these things out. However, since the fossil evidence is extremely thin, the mainstream may be proven wrong by a discovery being dug up as we speak. That’s how science works. Or the dissenters may be proven wrong, also. But I cheerfully concede that _currently_ the _mainstream_ is that Aves are part of Dinosauria. ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [January 21, 2019, 1:59am UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/26 "2019-01-21T01:59:11Z")
> [@Babale](#): > > Also, from your first link: > > “A minority of scientists prefer the hypothesis that birds evolved from small, arboreal archosaurs like Longisquama. They see these as ectothermic animals that adapted to gliding by developing elongated scales and then pennaceous feathers. This hypothesis, however, is not supported by cladistic analysis.” > > Not supported by evidence… > > Your second link goes to Yahoo Answers so forgive me if I don’t take it seriously. It’s “not supported by cladistic analysis.” Cladistics is not the end all be all of science. And again that is being argued as we speak. That simply shows the arguments going on, so your _ad hominem_ is not needed. However, I posted several peer reviewed articles. ---
**Author:** ![Jet\_Jaguar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jet_jaguar/32/3562_2.png) [@Jet\_Jaguar](https://boards.straightdope.com/u/Jet_Jaguar)\ **Post date:** [January 21, 2019, 2:20am UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/27 "2019-01-21T02:20:41Z")
> [@Darren\_Garrison](#): > > [Found it](https://boards.straightdope.com/sdmb/showthread.php?t=137499). And [this](https://boards.straightdope.com/sdmb/showthread.php?p=2476398#post2476398) is what the guy said to you here in GQ. Wow, it’s been 17 years already! Man, I’m getting old. :eek: Anyway, it looks like that poster wasn’t a fan of either Horner nor Bakker, so I don’t know what to tell everybody (he/she hasn’t logged on since 2003, so there’s probably no way to ever know). It’s been a long time, but I think I brought up the sacral brain thing in that thread because I had read Bakker’s “The Dinosaur Heresies” not too long before, and I didn’t realize that it was considered outdated. ---
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [January 21, 2019, 5:56am UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/28 "2019-01-21T05:56:41Z")
> [@DrDeth](#): > > It’s “not supported by cladistic analysis.” Cladistics is not the end all be all of science. And again that is being argued as we speak. > > That simply shows the arguments going on, so your _ad hominem_ is not needed. However, I posted several peer reviewed articles. It’s totally fine to study the question of whether dinosaurs are the ancestors of birds. It’s also fine to dispute the scientific consensus and test a new hypothesis. Almost everyone who has done so has concluded that birds are descended from dinosaurs, aside from a few fringe dissidents. Just because they are fringe doesn’t make them wrong, but in this case the evidence seems to be strongly against them. Not just cladistic evidence either-- we have transitioned forms between ground dwelling theoropods and birds. The researchers who buy into BAND seem to have a preset idea of what the ancestor of birds should look like, and since ground dwelling theoropods don’t fit the bill (no pun intended) they look to small arboreal lizard-like creatures that lived millions of years before birds did (while avian dinosaurs lived alongside more modern birds, and the fossil record is full of transitionary forms so close that scientists constantly argue over whether a given dinosaur is a true bird or only a bird-like theoropod). ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [January 21, 2019, 10:48am UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/29 "2019-01-21T10:48:14Z")
I gleaned the following clading diagram from Wikipedia. Is it more-or-less correct? Obviously it’s highly simplified and omits several extinct orders. Phylum Chordata | |\_\_\_ Tunicates & Lancelets | |\_\_\_ Hagfishes | |\_\_\_ Lampreys | |\_\_\_ Sharks & Rays etc. | |\_\_\_ Spiny Sharks (extinct) | |\_\_\_ Ray-finned fishes | |\_\_\_ Coelacanths | |\_\_\_ Lungfishes | |\_\_\_ Frogs & Salamanders | |\_\_\_ Mammals | |\_\_\_ Turtles | |\_\_\_ Snakes & Lizards | |\_\_\_ Crocodiles | |\_\_\_ Pterosaurs | |\_\_\_ Stegosaurs, etc. | |\_\_\_ Brontosaurs, etc. | |\_\_\_ Ceratosaurs, etc. | |\_\_\_ Allosaurs, etc. | \_\_\_ Tyrannosaurs & Birds, etc. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [January 21, 2019, 12:01pm UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/30 "2019-01-21T12:01:42Z")
> [@septimus](#): > > I gleaned the following clading diagram from Wikipedia. Is it more-or-less correct? > […] > | > |\_\_\_ Mammals > | > |\_\_\_ Turtles > | > |\_\_\_ Snakes & Lizards > | > |\_\_\_ Crocodiles Not quite - the snake-lizard/other reptiles split happens _before_ the [turtles](https://en.wikipedia.org/wiki/Pantestudines)/archosars split, AFAIK the c[urrent position](https://en.wikipedia.org/wiki/Reptile#The_position_of_turtles)to be. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [January 21, 2019, 3:12pm UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/31 "2019-01-21T15:12:29Z")
> [@MrDibble](#): > > Not quite - the snake-lizard/other reptiles split happens _before_ the [turtles](https://en.wikipedia.org/wiki/Pantestudines)/archosars split, AFAIK the c[urrent position](https://en.wikipedia.org/wiki/Reptile#The_position_of_turtles)to be. Thank you very much! (It looks like this is a relatively recent correction; my old diagram might have been compatible with the Wiki pages of several years ago.) ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [January 21, 2019, 4:02pm UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/32 "2019-01-21T16:02:11Z")
It’s still not a settled thing, as the articles make clear, but I’d bet on the genetics vs pure fossils ---
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [January 21, 2019, 4:20pm UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/33 "2019-01-21T16:20:01Z")
Hey **MrDribble** , interestingly enough the only criticisms of Cladistics I can find out there are from the DANB crowd. I find that very interesting… I’m not sure why you’re against Cladistics. What issue with that discipline do you have? Cladistics is the idea that we should group living things based on their ancestry rather than their characteristics. You are against This? Note that using genetic evidence to place an animal within a group based on ancestry is a form of Cladistics. Cladistics is not only based on fossils, and it’s not only applicable to extinct species. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [January 21, 2019, 6:22pm UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/34 "2019-01-21T18:22:56Z")
Ermm, firstly, get my name right Secondly - what on Shub-Niggurath’s Hundredth Left Tit gives you the idea I’m against cladistics? ---
**Author:** ![Babale](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/babale/32/15666_2.png) [@Babale](https://boards.straightdope.com/u/Babale)\ **Post date:** [January 21, 2019, 6:57pm UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/35 "2019-01-21T18:57:21Z")
Doh! I think I’ve been mixing up you and DrDeth and that’s where the extra R came from… sorry about that. I was trying and failing to respond to this post: > [@](#): > > It’s “not supported by cladistic analysis.” Cladistics is not the end all be all of science. And again that is being argued as we speak. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [January 29, 2019, 1:51am UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/36 "2019-01-29T01:51:54Z")
[The latest in dinosaur feather analysis](http://www.sciencemag.org/news/2019/01/fossil-feathers-reveal-how-dinosaurs-took-flight). ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [January 29, 2019, 2:39am UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/37 "2019-01-29T02:39:57Z")
> [@Darren\_Garrison](#): > > [The latest in dinosaur feather analysis](http://www.sciencemag.org/news/2019/01/fossil-feathers-reveal-how-dinosaurs-took-flight). Interesting. Science marches on. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [January 29, 2019, 11:27am UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/38 "2019-01-29T11:27:08Z")
Cool link, thanks. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [January 29, 2019, 3:19pm UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/39 "2019-01-29T15:19:00Z")
> [@DSYoungEsq](#): > > When I learned about “dinosaurs” back as a child in the 60s, there was very little distinction made in the juvenile books I was reading between different types of reptilian creatures of the Mesozoic Era. So we cheerfully called pteranodons, pterodactyls, plesiosaurs, etc. “dinosaurs”, because that’s how they were presented (it’s quite possible that there were distinctions being made in the books I read, but a seven-year-old often doesn’t bother with such things). And, of course, the whole idea that modern birds are just “dinosaurs” that survived extinction wasn’t really being discussed at the time. They may well be “dinosaurs” in a biological classification sense, but you’ll never convince the public that they are “dinosaurs” in an every-day usage sense. Well, there you go, Gramps. You’re going off of what was published in kid books 50 some-odd years ago, which was probably 20 or more years out of date versus the state of the paleontological art of the time. They probably didn’t mention feathered dinosaurs, warm blood or any of the other critical things we now know about them. Even the kid books draw those distinctions these days- they point out that certain lineages of dinosaurs developed as early as the Jurassic (prior to Archaeopatryx), and eventually evolved into something similar to today’s birds by the Cretaceous- they go so far as to show a Tyrannosaurus skeleton and a chicken skeleton together and note how absolutely similar they are. The other creatures- the aquatic icthyosaurs and mosasaurs are contemporaries of dinosaurs, but strictly speaking aren’t dinosaurs. It’s like considering whales or dolphins fish, because they live in the ocean. It sounds like a lot of people think “reptilian creatures that lived during the Jurassic, Triassic or Cretaceous periods = dinosaur”, even though we can easily point at alligators and crocodiles which evolved during those periods, and point out that they are not dinosaurs. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 29, 2019, 3:47pm UTC](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027/40 "2019-01-29T15:47:27Z")
> [@](#): > > The other creatures- the aquatic icthyosaurs and mosasaurs are contemporaries of dinosaurs, but strictly speaking aren’t dinosaurs. It’s like considering whales or dolphins fish, because they live in the ocean. Of course, ironically, whales and dolphins (and icthyosaurs and pleiseosaurs and T. rexes and humans) are fish, after all. [Previous page](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027.md?page=1) [Next page](https://boards.straightdope.com/t/what-is-and-isnt-a-dinosaur/828027.md?page=3)