A little while ago, news of a new paper by Devon Quick and John Ruben, both of Oregon State University, appeared on the newswires. It got its fair share of publicity.
Entitled 'Cardio-pulmonary anatomy in theropod dinosaurs: implications from extant archosaurs', the paper (Quick & Ruben 2009) purports to show that modern birds are fundamentally different from non-avian dinosaurs in terms of abdominal soft-tissue morphology, ergo birds cannot be modified dinosaurs. In slightly more detail, the paper asserts that a specialised 'femoral-thigh complex', combined with a synsacrum and ventrally separated pubic bones, provides crucial mechanical support for the abdominal wall in modern birds, and has thereby allowed the evolution of large abdominal air-sacs that function in respiration. In contrast, say the authors, theropod dinosaurs (non-avian theropods from hereon, thank you very much) lack these features and, worst of all, had a highly mobile femur that cannot have been incorporated into abdominal support - ergo, non-avian theropods cannot have had abdominal air-sacs that functioned like those of modern birds, ergo non-avian theropods were fundamentally different from modern birds. The implication from this - it's not mentioned in the paper but was of course bigged-up in the press interviews - is that birds cannot be dinosaurs! [adjacent Grey heron Ardea cinerea photo by Neil Phillips].
I said a while ago that I wasn't planning to cover this research, predominantly because I don't find it at all interesting nor worthy of review. After all, Ruben and colleagues seem to have made a career of publishing papers in which they assert that 'birds cannot be dinosaurs because of [insert supposed fatal flaw in the 'birds are dinosaurs' model]', and there's no indication that criticism of their conclusions will cause them to stop now. However, a brief discussion held over at Penguinology has changed my mind: we should try and set the record straight. Or, with great power comes great responsbility, or whatever. What makes this research particularly grating is that, like all the other papers by Ruben, Feduccia, Martin and colleagues, the 'birds are not dinosaurs' movement relies on two under-handed tricks that should be exposed.
Firstly, the papers never really demonstrate anything, but merely try to shoot holes in a given line of supporting evidence. So...
-- respiratory turbinates supposedly falsify dinosaur endothermy (Ruben et al. 1996), even though it's never been demonstrated that respiratory turbinates really are a requirement for any given physiological regime, and even though there are endotherms that lack respiratory turbinates
-- the innards of Sinosauropteryx and Scipionyx supposedly falsify avian-like air-sac systems in non-avian coelurosaurs and demonstrate a croc-like hepatic piston diaphragm (Ruben et al. 1997, 1999), even though a gigantic dose of personal interpretation is required to accept that this claim might be correct, even though crocodilians and dinosaurs are fundamentally different in pelvic anatomy, and even though some living birds have the key soft-tissue traits reported by Ruben et al. in Sinosauropteryx and Scipionyx yet still have an avian respiratory system [alleged diaphragm of Sinosauropteryx highlighted in adjacent image; unconvincing on all levels]
-- the weird leg proportions of birds supposedly falsify the classification of indisputably feathered Caudipteryx as non-avian (Jones et al. 2000), even though there is overlap between birds and non-birds in these data, and even though most of the data is screwy or suspect anyway (Christiansen & Bonde 2002, Dyke & Norell 2005)
... and so on.
Secondly, the papers either practise extremely selective citation, or fail to cite or mention stuff that contradicts what they say. One example: the size and shape of the sternal plates in non-avian coelurosaurs might have important implications for the respiratory physiology used by these animals (read on), yet Ruben and colleagues have repeatedly shown a schematic and incorrect diagram that shows the maniraptoran sternum to be a tiny little blob located along the ventral midline. In fact, the sternum was a gigantic plate (or two gigantic plates), similar to that of birds. In the new paper, Quick & Ruben (2009) figure a dinosaur skeletal reconstruction from 1916, which seems bizarre given that this is now substantially inaccurate in ways that are potentially important to the strength of their case (read on for more on this) [here's the actual reconstruction that Quick & Ruben (2009) use: that's right, Osborn's Tyrannosaurus from 1916, with three fingers and everything].
The hypothesis of 'paradoxical collapse'
As mentioned above, Quick & Ruben (2009) assert that non-avian theropods were fundamentally different in abdominal morphology from extant birds, and they hypothesise (note: hypothesise) that the sub-horizontal avian femur and its associated musculature might be required to prevent collapse of the lateral abdominal wall: most non-avian theropods evidently moved their femora a lot during normal locomotion, hence the femur could not have provided mechanical support to the abdominal walls and hence, say Quick & Ruben, could not have had abdominal air sacs that functioned like those of birds. As we'll see below, this doesn't mean - say the authors - that air-sacs were absent, just that they couldn't have been used like those of birds without paradoxical collapse being a problem. The main problem with this is that it's a hypothesis, or in other words a suggestion, and the authors do say this in the paper (p. 7 of the preprint). Does this hypothesis withstand observation?
The authors would like it to, but, no, it doesn't because the femur is not held sub-horizontally all the time in all birds. Many people know that the thigh moves extensively in running ostriches, and hence there's a lot of time in the running cycle when the thigh isn't providing this supposedly critical support to the abdominal wall. Worst still, ostriches are not unique: the thigh might be sub-horizontal in a standing bird, but the thigh moves up and down, in normal movement, in just about all birds [femoral movement in a guineafowl shown in adjacent image; from Gatesy (1990)]. Strangely, the authors acknowledge this (p. 10 of the preprint), yet still imply throughout the paper that the avian thigh somehow provides a sort of abdominal support that's different from what's seen in other theropods.
I really don't get it: why?? Where is this difference? Here we might find the reason for Quick & Ruben's use of the semi-erect tyrannosaur reconstruction from 1916: when posed like this, theropods have a large, unsupported space between the femur and the posterior end of the ribcage. Yet accurate, modern reconstructions (where the body is posed more horizontally, and the femur is slanted anteroventrally) reduce the size of this space. Quick & Ruben (2009) also note that the avian synsacrum might play a role in preventing paradoxical collapse, but this is not explained, nor it is clear how modern birds are fundamentally different from non-avians in this respect. They also argue that modern birds have much larger 'free pelvic cross-sectional area' than do non-avian theropods (that is, there's more space between the two halves of the neornithine pelvis than there is in the non-avian theropod pelvis): this is true, but, at best, all it means is that non-avian dinosaurs had less space for abdominal air-sacs. It not does demonstrate that they were absent. It all looks like an effort to make non-avian theropods and birds fundamentally different, whereas they actually aren't, and all of the features that seem distinct between the 'extremes' actually form part of a continuum.
In conclusion, paradoxical collapse is probably not a fatal problem for the function of large, avian-style respiratory air-sacs.
Abdominal air-sacs: a role in respiration, or not?
While Quick & Ruben (2009) argue that abdominal air-sacs cannot function in respiration without the 'femoral support' discussed above, they seem not to reject the existence of abdominal air-sacs... instead, they reject the possibility that the sacs were used in avian-style respiration, arguing instead that weight loss was their primary function. Ok, so they agree that abdominal air-sacs were present. Why do they reject, in non-avian dinosaurs, the role of abdominal air-sacs in respiration? Why? Answer: because, so they say, non-avian dinosaurs lack the sternal and costal anatomy required to ventilate air-sacs. Oh really? [image below shows the distribution of air-sacs in a neornithine bird, from Wedel (2003) but modified from Duncker (1971). Note the enormous sternum].
As is well known, birds use extensive dorsoventral movement of their often enormous sternum to ventilate their abdominal air-sacs, and hence their lungs. Quick & Ruben (2009) assert that sternal movement - of the sort used by birds - was not possible in non-avian dinosaurs; they say this because 'in nonavians, sternocostal articulations are flat wherein the distal sternal ribs abut the lateral edges of the sternum to form gliding, synovial joints or firmer, cartilaginous articulations and bird-like motion of the sternum is not permitted' (p. 6 of the preprint). The idea that birds rely on dorsoventral movement of their sterna, and that a huge sternum and associated mobile, ossified sternal ribs are a requirement for avian-style respiration, has been heavily promoted in other Ruben and colleagues papers (though Quick & Ruben (2009, pp. 9-10 of the preprint) do note that sternal length might not be important: read on) [ossified sternal ribs and complex sternocostal joints of a neornithine shown below, from Quick & Ruben (2009)].
Well, ignorance is bliss I suppose. There are two major problem areas here.
Contrary to these assertions (Ruben et al. 1997, 1998, Chinsamy & Hillenius 2004, Quick & Ruben 2009), data from living birds shows that neither a gigantic sternum, nor ossified sternal ribs, nor complex, rotating joints between the sternal edges and the sternal ribs, are requirements for avian-style ventilation of the abdominal air-sacs. To their credit, Quick & Ruben (2009) do note that some birds (including kiwis, emus and the extinct elephant birds and mihirungs) have very small sterna that don't extend as far posteriorly as the abdominal air-sacs: these sterna are actually smaller, compared to trunk length, than those of such non-avian saurischians as dromaeosaurs and diplodocoid and macronarian sauropods (Wedel 2007). However, it's not clear why ossified sternal ribs, or sternal ribs with a particular kind of articulation with the sternal plate, have been deemed so important by Ruben and colleagues: the thoracic ribs and their attendant cartilaginous ribs could do the job just as well, and indeed function perfectly well in the respiratory mechanics of most tetrapods.
The second major problem is that the (often large) sternal plates of some Cretaceous non-avian theropods are usually poorly preserved or distorted, and they're often not preserved at all. One might get the impression from Quick & Ruben's (2009) statement that we have many specimens to go on, but it would be more honest to admit that we really don't have as much information here as we might like. Furthermore, which specimens did Quick & Ruben (2009) have in mind when making the assertion quoted above? They don't say: they merely cite Hillenius & Ruben (2004) and, guess what, this paper doesn't even mention the subject of sternal ventilation or sternal rib morphology.
As it happens, there are in fact a couple of non-avian theropod specimens that are particularly informative here. In the Spanish ornithomimosaur Pelecanimimus, Pérez-Moreno & Sanz (1999) described 'slightly ginglymous' joints between the costal processes on the sternum and the sternal ribs, while in the dromaeosaur Sinornithosaurus, Xu et al. (1999) stated that the sternal rib facets on the sternum 'imply the presence of hinged sternocostal joints in dromaeosaurids, which is not concordant with recent arguments about the ribcage-pectoral girdle complex and the respiratory pattern of theropods' (p. 263: they were referring to Ruben et al. (1997)). In the dromaeosaur sternal plate described by Godfrey & Currie (2004), the sternal articulations for the sternal ribs are 'smooth, roughly circular' (p. 147). Finally, the sternal rib processes in Bambiraptor haven't been described in detail, but they look like convex structures that would have permitted sternal rib rotation (Burnham et al. 2000, Burnham 2004) [the large sternal plates of Velociraptor shown in adjacent image, from Norell & Makovicky (1997). These sternal plates are 20% the length of the trunk: proportionally longer than those of kiwis (17%) and other neornithines with a fully functional set of abdominal air-sacs (Wedel 2007)].
These articulations (I'd be interested to know if others have been described in the literature: this seems to be about it) indicate mobile, synovial sternocostal joints, exactly what Quick & Ruben (2009) say are absent. So thorax morphology in at least some non-avian theropods does indicate that avian-style movement of large, avian-style sternal plates, sternal rib and sternal rib facet morphology was present. As discussed above, however, enormous sternal plates and 'special' sternocostal joints aren't required for avian-style air-sac ventilation in the first place, and saurischian dinosaurs (yes, sauropodomorphs as well as non-avian theropods) do possess the anatomical features required for an avian-style air-sac system.
Papers with a hidden agenda
In conclusion, the presence of abdominal air-sacs in non-avian dinosaurs seems agreed upon - and if you need to know more about the evidence for these structures then go on over to SV-POW! Evidence for the existence of sternocostal movement in coelurosaurian theropods looks good, despite what Quick & Ruben (2009) say. If we combine these bits of information, the logical conclusion is that non-avian theropods were using their sterna and sternal ribs to ventilate their abdominal air-sacs, and here is the avian condition, albeit in less 'extreme' form. The raison d'être of Quick & Ruben's (2009) paper is to assert that sternocostal movement didn't happen (when it probably did), and to propose that the thigh was somehow integral to the prevention of 'paradoxical collapse' (when it doesn't seem at all clear why this should be so) [the adjacent picture seems to be accompanying quite a few of the discussions of Quick & Ruben (2009) seen online. I don't know where it came from].
A particularly sympathetic interpretation of their paper might be that enlarged, abdominal air-sacs didn't function in respiration until after the sub-horizontal femur was in place to prevent 'paradoxical collapse'. As outlined here, this is not in agreement with the evidence and can be rejected... but at least it sounds like a proper scientific hypothesis.
A less sympathetic interpretation might be that this is another poor attempt to try and shoot holes in what is actually a tremendously well supported phylogenetic model. What I really object to is the fact that Quick & Ruben (2009) seem to have written their paper with a hidden agenda in mind: in all of the press statements, they've been touting the idea that their paper helps falsify the dinosaurian ancestry of birds, with statements such as the following being thrown around: "It just seems pretty clear now that birds were evolving all along on their own and did not descend directly from the theropod dinosaurs, which lived many millions of years later" (this one was from Devon Quick). Yet this aspect of their approach is not discussed in the paper, nor stated explicitly. This is just downright dishonest. Look, if you have a problem with an idea - so much so that it inspires you to write a paper looking at one aspect of that subject, and so much so that you feel the need to discuss it at length with any journalist who displays interest in your research - at least have the decency and the balls to put your objections and reasoning into the technical literature. Papers are meant to report results, observations and hypotheses: they are not vehicles that allow you to preach your hidden agenda to the press.
The fact that Ruben has been saying things to the press like "Frankly, there's a lot of museum politics involved in this, a lot of careers committed to a particular point of view" doesn't encourage you to think that the authors have a realistic view of how and why we got where we are in the bird origins debate. Of course, creationists just love what Quick and Ruben have been saying.
Refs - -
Burnham, D. A. 2004. New information on Bambiraptor feinbergi (Theropoda: Dromaeosauridae) from the Late Cretaceous of Montana. In Currie, P. J., Koppelhus, E. B., Shugar, M. A. & Wright, J. L. (eds) Feathered Dragons. Studies on the Transition from Dinosaurs to Birds. Indiana University Press (Bloomington & Indianapolis), pp. 67-111.
- ., Derstler, K. L., Currie, P. J., Bakker, R. T., Zhou, Z. & Ostrom, J. H. 2000. Remarkable new birdlike dinosaur (Theropoda: Maniraptora) from the Upper Cretaceous of Montana. The University of Kansas, Paleontological Contributions 13, 1-14.
Chinsamy, A. & Hillenius, W. J. 2004. Physiology of nonavian dinosaurs. In Weishampel, D. B., Dodson, P. & Osmólska, H. (eds) The Dinosauria, Second Edition. University of California Press (Berkeley), pp. 643-659.
Christiansen, P. & Bonde, N. 2002. Limb proportions and avian terrestrial locomotion. Journal of Ornithology 143, 356-371.
Duncker, H. R. 1971. The lung air sac system of birds. Advances in Anatomy, Embryology, and Cell Biology 45, 1-171.
Dyke, G. J. & Norell, M. A. 2005. Caudipteryx as a non-avialan theropod rather than a flightless bird. Acta Palaeontologica Polonica 50, 101-116.
Gatesy, S. M. 1990. Caudofemoral musculature and the evolution of theropod locomotion. Paleobiology 16, 170-186.
Godfrey, S. J. & Currie, P. J. 2004. A theropod (Dromaeosauridae, Dinosauria) sternal plate from the Dinosaur Park Formation (Campanian, Upper Cretaceous) of Alberta, Canada. In Currie, P. J., Koppelhus, E. B., Shugar, M. A. & Wright, J. L. (eds) Feathered Dragons. Studies on the Transition from Dinosaurs to Birds. Indiana University Press (Bloomington & Indianapolis), pp. 144-149.
Hillenius, W. J. & Ruben, J. A. 2004. Getting warmer, getting colder: reconstructing crocodylomorph physiology. Physiological and Biochemical Zoology 77, 1068-1072.
Jones, T. D., Farlow, J. O., Ruben, J. A., Henderson, D. M. & Hillenius, W. J. 2000. Cursoriality in bipedal archosaurs. Nature 406, 716-718.
Norell, M. A. & Makovicky, P. J. 1997. Important features of the dromaeosaur skeleton: information from a new specimen. American Museum Novitates 3215, 1-28.
Pérez-Moreno, B. P. & Sanz, J. L. 1999. Theropod breathing mechanism: the osteological evidence. In Renesto, S. (ed) Third International Symposium on Lithographic Limestones (Bergamo, Italy). Revista del Museo Civico di Scienze Naturali 'Enrico Caffi' (Bergamo), Supplement to no. 20, pp. 121-122.
Quick, D. E. & Ruben, J. A. 2009. Cardio-pulmonary anatomy in theropod dinosaurs: implications from extant archosaurs. Journal of Morphology doi: 10.1002/jmor.10752
Ruben, J., Dal Sasso, C., Geist, N. R., Hillenius, W. J., Jones, T. D. & Signore, M. 1999. Pulmonary function and metabolic physiology of theropod dinosaurs. Science 283, 514-516.
- ., Hillenius, W., Geist, N. R., Leitch, A., Jones, T. D., Currie, P. J., Horner, J. R. & Espe, G. 1996. The metabolic status of some Late Cretaceous dinosaurs. Science 273, 1204-1207.
- ., Jones, T. D., Geist, N. R. & Hillenius, W. J. 1997. Lung structure and ventilation in theropod dinosaurs and early birds. Science 278, 1267-1270.
- ., Jones, T. D., Geist, N. R. & Hillenius, W. J. 1998. Ventilation and gas exchange in theropod dinosaurs. Science 281, 47-48.
Wedel, M. J. 2003. Vertebral pneumaticity, air sacs, and the physiology of sauropod dinosaurs. Paleobiology 29, 243-255.
- . 2007. Postcranial pneumaticity in dinosaurs and the origin of the avian lung. Ph.D. dissertation, University of California, Berkeley.
Xu, X., Wang, X.-L. & Wu, X.-C. 1999. A dromaeosaurid dinosaur with a filamentous integument from the Yixian Formation of China. Nature 401, 262-266.
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So you think it's wrong then. Am I right? ;-)
Outstanding Post! You have gone far beyond the normal expectations of your basic blog post - thanks. Can I nominate this for a Sci BLog Post Of The Year?
Thank you for a great post, Darren. I'd looked through the paper myself and was puzzled by its complete lack of support for the "birds are not dinosaurs" notion peddled in the press releases. Most striking to me was the use of T.rex for comparison and the fact they admitted that the features apparently vital to birds weren't present in the early birds anyway. But I hadn't picked up the rest of the flaws in their argument, thanks for sharing your knowledge of this.
What really annoys me with Ruben's comments in the media is the implicit double standard. Granting for the sake of the argument that the respiratory function of non-avian theropods was fundamentally different from that of birds, this is supposed to prove that birds are not theropods - repeating the argumentation further down the phylogenetic tree would then demonstrate that birds are not dinosaurs, not archosaurs, not diapsids, not amniotes, not tetrapods, not vertebrates, all the way down, since basal members of none of these clades have bird-like respiration (go far down enough and they don't have respiration of any kind!), yet Ruben quite fails to claim to have demonstrated separate abiogenesis for birds.
Very great post!
Darren, great post.
BTW - do they at least offer some useful insight into how respiratory system might have operated in non-avian dinosaurs?
At the risk of being called another sycophant, I must say this is another outstanding post Darren! The work of Quick, Ruben, Feduccia et al. barely rises above the level of pseudoscience and I think you outlined why that is so quite cogently. Like all pseudoscience, this work has a clear agenda and resorts to the worst chicanery in order to advance its view. As I've said before, they're no better than creationists when it comes to their use of science to try and prop up their favored worldview. But it just fails, time and again. I just don't understand what it is about the theropod ancestry of birds that galls them so much to cause them to go to such extreme (unethical) lengths to refute it? Were they scarred at some point by a dinosaur enthusiast? If someone is going to nominate you for an award, I heartily second that motion!
Thanks for this review. I was pretty skeptical when I first saw this in the news and I was pretty disappointed in the journalists for not being skeptical themselves and doing a bit of research or seeking comments from scientists who opposed the claims made by the authors. I guess they think it's okay to just give one side of the story when you're discussing a single paper that is supposedly rejecting an incredibly sound theory... this may be why I may more attention to blogs than news sites.
Creationism in short: Any gap in the fossil record, however minor, proves that Earth was created 5000 years ago by god.
BANDitry in short: Any anatomical difference between modern birds and mesozoic dinosaurs, however minor, proves that birds are flying drepanosaurs/ornithosuchians/crocs/doswellias/(insert Triassic hellasaur of your choice).
Thanks Darren, great post. Also, hard to believe, but yes the 1916 tail-dragging three-fingered T Rex illustration is in fact published in this peer-reviewed 2009 paper.
Ruben, Feduccia, Martin, and a handfull of others are being really stubborn and dogmatic in failing to see the clear dinosaur-bird link, making spurious objections rather than taking into account the at least 200 anatomical points of similarity between dromaeosaurs and birds. Even the late evolutionary theorist George Gaylord Simpson called the anatomical traits birds and dinosaurs share "demonstrably convergences", suggesting everyone is capable of prejudices that have nothing to do with evidence. Eventually, one can hope people will stop beating this very dead horse.
How did this paper PASS peer-review?
So, then, do these people think that birds independently evolved all of the characters they for-sure share with therapods? Yeah, it's possible that both chickens and Velociraptor had feathers because they're pretty and soft, but that's not very parsimonious. How do the anti-dino-bird folks explain away the (apparent) synapomorphies?
@Onychomys: Perhaps by sticking their fingers in their ears and closing their eyes?
Indeed Chris.
I had a creationist astronomy professor (yeah, you work that one out!), and the amount of clearly false information he spread in his classes was unreal--and when I called him out on it, he would mumble something indistinct and change the subject.
False information about astronomy, and especially grating was the blatantly false information about the fossil record.
What also astounds me is the holes these people (creationists specifically, but it seems that the BAND camp has very similar tactics) go through to try to hold onto their ideas--the mentioned professor actually went so far as to explain continental drift because the bible said that he created the 'land' 6000 years ago (Pangea broke apart into its current state in that time apparently) instead of 'lands'.
It was so surreal.
Excellent review of the arguments.
That's one of the things that pisses me off most about the whole situation. I know we all bring our own biases into the classroom, but teaching outright falsehoods is unethical and an affront to our role as educators, a role presumably based on facts. These guys are also teaching classes, meaning they are spreading false information to their students. I actually had a transfer student one year who argued openly with me about the bird-dinosaur link because they had had a class and done research with one of the BAND crowd. It is like arguing with a creationist. Sadly I only had a single lecture to discuss this and could not go over all the synapomorphies in detail. This argument is not going away because more BANDits are being produced it seems.
I don;t know what Ruben's deal is...I used to like his stuff a lot, back when he was a physiologist.
Weak as this argument is, though, I do think there are a lot of unanswered questions about the evolutionary transition from tidal lungs to avian one-way flow. I maintain again that there had to have been animals--whatever they were, taxonomically--with both airsacs and tidal lungs.
Coming soon - Peter Mihalda on the evolution of birds and why all paleontologists are whackos...
Thank you very much for your review of this paper!
In reference to comment 19: NO! Mihalda is banned for life.
Ruben was quoted in Science Daily as saying "A velociraptor did not just sprout feathers at some point and fly off
into the sunset", so apparently he doesn't accept Velociraptor was feathered, nor, by implication, that other feathered dinosaurs were. Heavens know how, or if, he explains away the rather rich record of deinonychosaur feathers ...
Is the tidal vs. flow-through lung just a false dichotomy because we can only examine extant forms? There is a student in Peter Dodson's lab (I forget her name) I met at NAPC who is doing some really interesting research I think will help shed some light on this question.
It saddens me that there are 'scientists' out there so wedded to dogma that it blinds them from facts.
But then I come here to this blog, and especially the comments section here, and feel a lot better. It is hard to believe that there are still places like this on the interwebs. Its like a refugia of logic and reason against an ice sheet of trolls, flame-baiting and porn!
My Biology teacher last year was a creationist, and she vehemently denied the existent of feathered dinosaurs on the basis of "imaginary feathers". Its amazing how these people even make it into the school system. I asked her about BAND without even explaining the acronym and she jumped on it saying how it was scientifically sound at that she loved Feduccia's paper on why feathered dinosaurs don't exist.
Anyway, later on I did a presentation in class on shark teeth transitional fossils from Chile and Peru, and she claimed that the fossils were fakes, altered, and put there by Yahweh in one sentence (well, two really).
She still winces every time I say I want to pursue a career in paleontology. I have to say that she started my whole idea of wanting to get into that field, seeing the kind of scientific ignorance in today's public.
Ending with the repetition of others, great post Darren, thanks!
Owned! Well done Darren! Wait until Jack Horner gets on the ball of completing his dinochicken experiment, thus further disproving these BANDits.
I maintain again that there had to have been animals--whatever they were, taxonomically--with both airsacs and tidal lungs.
In light of some of Steve Perry's work on crocs, I'd bet on the opposite: non-parabronchial airflow among chambers of lungs without air sacs. That airflow was probably not unidirectional, though, at least at the beginning.
There are numerous extant snake species that exhibit both tidal lungs (well, lung) and air sacs. So there's at least one extant group that had both. The bigger question for me, would be figuring out when bidirectional breathing was replaced with unidirectional. Do we have any osteological correlates for that?
Thanks, Matt. Suddenly that makes a lot of sense. I think that the posterior part of modern croc lungs is relatively nonvascularized... does Perry have evidence of atmospheric air bypassing gas exchange surfaces on the way back there? Do we know if the posterior airsacs of birds are lung derivatives?
I can understand referees not picking up on femoral details -- everybody's pressed for time -- but how can they let the paper go without citing relevant references? Isn't that the first thing a referee checks?
By the way, good catch on their mis-spelling "hypothesize" as "hypothesise". What a bunch of dumb-arses!
(:-) for the humor-impaired.)
Emma Schachner is the name of the grad student from NAPC I mentioned earlier (#23). The title of her poster was "Evolution of the archosaurian respiratory system: evidence from rib and vertebral morphology". Great work. Hopefully she'll start publishing this stuff soon. You can download the abstract volume here: http://www.napc2009.org/technical-program-and-abstracts
Thanks. Good piece of work. (And what a piece of work is John Ruben, these days. Sad.)
A few random associations:
BANDits now resemble creationists in many ways, one of the more entertaining ones being their inability to agree on which theropods are really theropods and which ones are really birds (and so not theropods), which exactly resembles the inability of creationists to agree on which hominid fossils are really apes and which are really humans (and so not apes. Feduccia seems to now be of the opinion (in contrast to Feduccia 10 years ago) that all maniraptorans, and perhaps even all coelurosaurs, are birds, not dinosaurs. Ruben seems to draw the line at Archaeopteryx.
By the way, what degree of femoral excursion would we reconstruct for the afore-mentioned Archy, and would it be too much to forestall the dreaded paradoxical collapse?
Have you, or has anyone, done as detailed a job on the other major BAND paper of the year, James & Pourtless 2009?
And I will note that BAND has at least managed to retain a fair proportion of ornithologists as at least agnostic on the bird-theropod question. How, I'm not sure, except that many ornithologists personally know more BANDits than dinosaur paleontologists. And for some reason, most avian paleontologists other than BANDits haven't been all that vocal, Rick Prum being the major exception.
Excellent refutation,the overwhelming evidence points to a Dino evolve to Bird thesis.
So...I can go back to tossing dinosaurs on the grill again?
"A velociraptor did not just sprout feathers at some point and fly off into the sunset" - John Ruben
But a small Triassic crocodylomorph did? Gee, how, um, what's the word...
BANDits deny raptors having feathers at all! They simply argue the feathers found on some raptors are not feather but some sort of skin outgrowth... (can they explain quill spines on Velociraptor arms????)
The thing is, ornithologists have been kept in the dark so long thinking there is nothing dinosaurian about modern birds - they simply take Audubon and question no further (or course I exaggerate but you get the point) - the dinosaurian origin of birds is not so important to them.
BAND gets popular because it proposes an origin from creatures so obscure (crurotarsans) that Ornithologists no longer have to worry about wrapping their minds around the similarity of T. rex to birds. Of course, if they took the time to research what crurotarsans were, they'd realize that's basically like saying birds evolved directly from crocodiles - a far less likely proposal.
Creationists.... if they don't fund or support BANDits, I'd bet they want to. Feduccia.... he's gone nuts. He said maniraptors are not related to birds because their feathers are nothing more than "skin filaments misinterpreted by the ignorant" but now he says they ARE birds (which assumes that the feathers are INDEED feathers!)
I suppose next he will try to make an argument for a flying Coelophysis!
I think one of the major insanities of the Feduccia lot is they have absolutely no understanding about modern phylogenetic techniques in regard to comparative biology and functional morphology amongst other things. It's bad science.
What's sad these days isn't that creationists love the arguments of Ruben and friends, it's that the "science" done by BANDits and creationists are almost indistinguishable in the errors they commit.
excellent post. Finally someone says it aloud: the BAND members have a hidden agenda, and are dishonest.
I also feel that their methods for spreading their ideas, including their dishonesty, makes them equal to typical creationists - why does any journal ever publish anything that is so far below par?
I was actually hoping you'd get around to this, now I know even more about just how damn burning-stupid wrong Ruben et al are :D
Oh yeah, probably the worst thing that I noticed from the ScienceDaily piece;
/facepalm
Nima:
Some of them do. Others claim that raptos aren't dinosaurs.
No, I don't get the point. Except that the origin of birds isn't important to most ornithologists. Nor should it be.
Only a few BANDits claim that birds are crurotarsans. They can't agree on that either. I really don't understand why you think this would make them popular with ornithologists.
That's something else that annoys me about BANDits - they're much more interested in what birds (allegedly) are not than what they (supposedly) are. They're disputing an explanation without more than token efforts to provide an alternative one.
Ruben's theorisation shouldn't be confused with mine. The only thing I share with him on this is one basic aspect of the phylogeny. I glanced at the paper but I'm not going to defend it here or anywhere.
There's not much point in accusing him of a hidden agenda though, since pretty well everything anybody ever does reflects many of their aims and ideals, and they can't all be detailed every time anyone says anything. This applies to scientists and their papers, and certainly to Ruben's opponents. There's plenty that cladist dinobirders leave out in every paper they write.
@11 Raymond Minton:
Similarity between type A and type B says nothing about direction of any descent, but this seems to be a lesson yet to be learned by many dinobirders - such as Angela Milner for example. Of course it may be that Quick and Ruben feel droms and moderns are not close, dunno, but that has no relevance to my views, or BAND in the wider sense.
The paper helped creationists no more than any science not well based on Popperian principles. Cladism is just another form of religion - the adherents often don't use evidence well, and they don't listen to counter arguments properly. Yes, plenty of commenters here have found ways to criticise this paper, perhaps justifiably, but many here continue ignore the elucidations I've offered over the years.
Oh no, Darren! You banned Peter Mihalda but you forgot about hi twin brother John Jackson! HELP US ALL!
Shrug, I don't agree with him; but he's nowhere near as aggressively psychotic as Peter.
John, I'm not a big fan of the witch hunt card. As people like Bakker, Ostrom, Gauthier, etc. have shown it's very possible to reverse dogma if the evidence is on your side. And when you have something as strongly supported as the dinosaurian origins of birds, you need a lot of it.
It's evidence I"m convinced BAND doesn't have.
"BANDits deny raptors having feathers at all! They simply argue the feathers found on some raptors are not feather but some sort of skin outgrowth..."
What the crap? Uh, Microraptor??? Its obvious feathers, with barbs and veins and all that, are weird skin outgrowths? Are know BANDits are completely whacko, but... this is ridiculous.
"Shrug, I don't agree with him; but he's nowhere near as aggressively psychotic as Peter."
That is true.
Let us not forget the statement made by the great scientist Planck:
""An important scientific innovation rarely makes its way by gradually winning over and converting its opponents: it rarely happens that Saul becomes Paul. What does happen is that its opponents gradually die out and that the growing generation is familiarized with the idea from the beginning."
Given that BAD goes back to the very beginnings of modern evolutionary biology (i.e. Huxley) its growth has largely followed Planckian lines (e.g. Ostrom's post-Deinonychus younger generation successors). However, what has changed more recently is the use of the media to spread the BANDit message. If it were just Ruben and friends papers then they would have been quietly buried as bad science (not BAD). But just like Michael Behe's ID these guys keep themselves afloat via the press. To all educated outsiders it is rather clear that BAD trumps BAND even as evolution trumps ID.
While in practice science does not follow a Popperian script there is hardly any doubt that most core BANDit assertions are unfalsifiable theories just like that weird birds first thing you posted on.
This should be all that needs to be said about the entire BAND/ABSRD/MANIAC enterprise: it's nothing but a single bloated argument from ignorance.
What I'd like to know is who the editors and the referees were: ivory-tower neontologists who couldn't tell a dryosaurid from a dyrosaurid if it bit them in the proverbial ass?
Yes, it's on the DML somewhere.
One of the referees wrote to me (on the condition of anonymity) and told me, in detail, that his comments were ignored by the editors. He was probably deliberately chosen for being an ornithologist who has AFAIK never worked on anything outside Neornithes, but that wasn't enough to make him agree with the manuscript... I have permission to send his e-mails to the DML, but still haven't got around to doing it.
"Nothing makes sense in biology except in the light of evolution" (Dobzhansky).
"Nothing makes sense in evolution without a good phylogeny" (G. C. Gould & B. MacFadden 2002, 2004).
I know there are people who keep pretending that it's possible to do pure neontology. They should stop already.
So why do you make yourself a topic? You aren't mentioned or alluded to in the post or in any of the 42 comments that precede yours.
Man, are you ignorant.
Duuuuude. Of course everything before the comma is correct, and of course all people who work on Mesozoic dinosaurs (Kurzanov and his disciples excepted) know that full well!
Does the term "outgroup" ring any bells? Were you even aware that it's not possible to do cladistics with fewer than four taxa?
Isn't it obvious that Raymond meant "shared derived similarities" by "similarities"? Shouldn't it be the default assumption that he knows full well that all other similarities are irrelevant?
I think that's called the fallacy of false equivalence. Sure everybody has emotions, but you can try to be aware of them and keep them out of your science. You can at least try.
Once again I hereby ask you to elaborate. Once again I don't think it's likely you'll ever do that.
Translation: ME! ME! ME! PRECIOUS ME!!!1!
Get yourself together, read up on the science of phylogenetics, and then try to publish a paper. I suggest John Wilkins and Olivier Rieppel as reviewers.
Oh, it does. No, seriously, honestly.
What John Jackson overlooks is that the scientific method has a second part: the principle of parsimony. Falsification trumps parsimony, but the latter must be used wherever the former can't be applied (yet).
For example, he keeps repeating that cladograms aren't falsifiable. As far as I can see, that's strictly speaking true â it just doesn't matter, because a cladogram is the most parsimonious of all hypotheses (all of them unfalsifiable) that can explain a given dataset.
What is really falsifiable in phylogenetics? Any mutation can happen, selection can go stranger ways than we'd have imagined, no character is absolutely safe from homoplasy (even though SINE and LINE insertions come very, very close)... parsimony is all we have. So we better use it. It's the same principle we use to conclude that the computer in front of us doesn't work by witchcraft.
John Harshman asked:
Yeah, saw that. Not bad. Perhaps the strangest thing about that paper, aside from the fact that they represent lack of resolution as support for their preferred hypotheses, is that they credit Dave Swofford with advising them on analysis. They can't have paid much attention.
>>Oh, it does. No, seriously, honestly.<<
It is entirely possible you misunderstood what I meant.
Even if you were to take examples typically discussed such as Newtonian mechanics, quantum mechanics and relativity you probably do realize that the actual history of science did not follow the idealized Popper narrative. For the explanatory power of classical mechanics to be challenged you first needed new discoveries to happen e.g.the discovery of the electron that provided material for falsification of the former. Many of these discoveries did not happen as formal falsification attempts of classical mechanics or even as tests of its predictions but independent studies. There is even more serious stuff in this direction but then the intention was not to take off into a discussion of Popper.
At least I have no dispute with the latter part on parsimony and the like. There is a problem with the consistency of the argument used by the birds first fellows.
Firstly, the papers never really demonstrate anything, but merely try to shoot holes in a given line of supporting evidence.
Yeah ... but in general terms, critiquing other ideas is a legitimate part of science and intellectual inquiry. There's more worth doing than just putting up your own new theories.
Yes, but if you're going to critique other's ideas, you should have a better explanation to take its place. This is something both creationists and BANDits have yet to do.
Many thanks to everyone for comments. With regarding to Neil's comment (no. 55), it's true that flawed or erroneous statements or conclusions should of course be criticised where appropriate. Science is self-correcting. Note that the critiques produced by Ruben and colleagues do not ever really overturn the respective hypothesis or observations; rather, they make erroneous complaints that are either inconsistent or fail to take account of the evidence we have (one example: look at their work on the alleged presence of hepatic piston diaphragms in theropods, which fails to credit work on the anatomy of birds, non-avian theropods and crocodilians). Like quite a few people it seems, I used to have great respect for Ruben when he published on the respiratory physiology of extant animals. In fact I thought there was some mistake when I first heard that he was saying that birds and theropods were only similar via convergence, and that he had teamed up with Feduccia. Alas.
Regarding the James & Pourtless (2009) paper, I entirely agree with the points made by Scott in his critique. I penned a few comments on the paper here... but here they are again...
As for James & Pourtless (2009): these authors use cladistics to test the hypothesis that birds are deeply nested within coelurosaurian theropods, and argue that they use an unbiased approach where non-dinosaurian archosaurs and other reptiles are included too (they include Longisquama among archosaurs for some reason, and even imply that it's a proto-bird [p. 37]). The paper is full of really weird claims (e.g., that theropods can only be diagnosed by their intramandibular joint) and does a lot of stuff that's bound to skew the results: they coded all characters of disputed homology as 'unknown' (p. 14), for example (and, as usual among those disputing the theropod affinities of birds, they ignore evidence showing that the disputes about homology are erroneous anyway). This is wrong because it makes an a priori assumption about homology, and it introduces loads of new question marks in the matrix for character states where we do have data. Furthermore, the choice of taxa is weird: it's wrong to analyse theropods and other archosaurs without including at least some non-theropod dinosaurs. Finally, the trees they generated are entirely uninformative (they are mostly polytomies) and don't provide support for any hypothesis, so quite how the authors can say that they found weaknesses in the 'birds are theropods' hypothesis is really not apparent. As an impartial test of archosaur phylogeny, this study fails miserably.
No, they absolutely need to know something about where Neornithes comes from. They need a bit of context. After all, everything is the way it is because it got that way (Haldane).
Not much, but they should have some idea about it.
It's just not feasible, because nothing in biology is understandable without some amount of knowledge about its history.
Ah, OK. If you're that strict ("formal falsification attempts"), I agree; I just don't think intentions matter that much.
That's not actually true.
However, if you're going to critique an idea and pretend to have a better explanation to take its place, that explanation should actually be better. Both creationists and BANDits fail to take into account that their explanations are much, much, much worse. They just gloss over it, because they don't notice it -- they lack the knowledge that's necessary for that.
What I forgot to mention yesterday: the specimen of Sinosauropteryx figured above is squished flat. It might just as well be two-dimensional. To read the shape of any soft tissue directly from such a fossil is naïve in the extreme.
What I forgot to mention yesterday: the specimen of Sinosauropteryx figured above is squished flat. It might just as well be two-dimensional. To read the shape of any soft tissue directly from such a fossil is naïve in the extreme.
It's worse than that, even. As Duncker illustrated back in 1971, the liver of the carrion crow spans the entire vertical distance between the sternum and vertebrae. But this does not divide the body cavity into anterior and posterior spaces, as Ruben et al would have it, because the vertically tall liver is also narrow, and the air sacs go by on either side.
So we could grant Ruben et al. every single claim they make about the specimen's morphology and they're still dead wrong about it indicating the absence of airsacs, as was compellingly shown in the literature before I was born.
For a long time I tried to be collegial about all this, in hopes that the BANDits really were serious about science and were just interpreting the evidence differently. But they're not. They're either knowingly lying or just profoundly, breathtakingly stupid. If you're trying to decide which, the fact that they went back to 1916 to find a theropod reconstruction that seems to support their case here should give you a clue.
They're either knowingly lying or just profoundly, breathtakingly stupid. If you're trying to decide which, the fact that they went back to 1916 to find a theropod reconstruction that seems to support their case here should give you a clue.
You forgot "a reconstruction that a 10 year old kid with an interest in dinosaurs could point out was wrong".
My vote is for knowingly lying. Scott Hartman has said on the DinoForum that he has observed BANDits actually sitting down and discussing what needs to be published, and what conclusions will be reached - before they do the research. These dudes are on the level of creationists. I will now describe a cartoon I saw somewhere:
Scientific method: (male scientist at a desk surrounded by hominid skulls, beakers, papers, etc says to female colleague) "Here are the facts. What conclusions can we draw from them?"
Creationist method: (male minister pointing to a book labeled 'Genesis' says to male church goer) "Here is the conclusion. What facts can we find to support it?"
BANDits are the same as creationists, except that the conclusion is not Genesis but "birds are not dinosaurs".
Me: And what's wrong with pure neontology?
David Marjanovic: It's just not feasible, because nothing in biology is understandable without some amount of knowledge about its history.
Me again: Your fallacy lies in assuming that paleontology is the only way we learn about history. I would claim that we actually learn more about the history of Neornithes from neontology than from paleontology. Of course phylogenetics is a historical science, but it's primarily a neontological historical science.
John, but if I remember correctly many molecular clocks used to determine divergence times are calibrated with the fossil record. Plus we're now able to recover some molecules from fossil bones. Molecules that can be compared with modern ones. Likewise paleontologists can use modern ecological theory to help understand extinct ecosystems. Those are just a couple examples and I am sure there are more. Neither neontologists nor paleontologists should imagine their respective fields exist in a vacuum. The most exciting science crosses boundaries.
Here's a very accurate text I wrote that involves a BANDit:
http://johnfaa.deviantart.com/art/Idiot-people-are-idiot-130053425
Chris,
I agree with all of this, but none of it seems to me to be relevant to the point of whether pure neontology is possible. David is assuming that because evolutionary history is crucial to much in ornithology, we must use paleontology to understand that history. I'm saying we have perfectly good neontological sources for most of that knowledge. I don't say paleontology is useless. In fact I don't think there are enough paleo-ornithologists, and the fossil record of birds is therefore underused. But I also think that most of what we are going to be able to learn about bird evolution is going to come from neontology.
While I agree that birds evolved from dinosaurs, I have to put the line through dinosaurs were birds. Unfortunately there are too many transitions that muddy what is bird and what is dinosaur but what is obvious is that they neither are reptiles. Perhaps Dinosauromorpha might be a sister clad to Archosauromorpha too but more distance between them.
To John: Ok, I can see where you're coming from now.
To everyone: Is there anyone out there who is willing to try presenting the dino-bird link data at an ornithology meeting? Has anyone done this before?
It's funny that so many scientists believe this, vehemently. It says something about the psychology of (most) people who self-select to become scientists, independently of what science itself requires. A scientist starts out as somebody who needs to know, and to go from a theory to no theory feels like going from knowing to not knowing. Almost as bad is going from one theory to two theories; science is happy, but the scientists are miserable.
Hi Darren, do you think you can be tempted to tackle any of Olivier Rieppel's paper's on how snake skulls are 'fundamentally different' from lizards'?
Chris Noto (68)-- I don't go to ornithology meetings, so I can't answer your exact question, but there was an article presenting BAD and why it ought to matter to ornithologists in "The Auk" some years back. The issue had cover art of a bunch of Microraptors climbing in a forest. So yes, the argument has been presented to the ornithological community.
Yup, the article concerned is...
Prum, R. O. 2002. Why ornithologists should care about the theropod origin of birds. The Auk 119, 1-17.
... which then provoked...
Feduccia, A. 2002. Birds are dinosaurs: simple answer to a complex problem. The Auk 119, 1187-1201.
Feduccia's article has lots about digital homology; he also claims that birds and theropods have different teeth (this is known to be a false dichotomy), argues that Longisquama is informative for feather origins (this has been convincingly contested), tries to argue that theropod fibres/feathers are like ichthyosaur skin fibres (this is obviously wrong), and points to a 'temporal paradox' (which is actually non-existent; it's an enduring fallacy maintained by the BANDits). His inconsistency is amusing: most of the article is spent showing that dromaeosaurs and other maniraptorans are radically different from birds (he even says, on p. 1194, that Microraptor cannot realistically be shown with feathers), yet by the end of the article he is arguing that dromaeosaurs are actually birds. Whether that's true or not (character evidence currently indicates that it's not), the point is that dromaeosaurs and birds must be incredibly similar if he's able to say that, making a mockery of the previous 11 pages of Feduccia's 15 page article. All in all, I can say without bias that this is crap science.
Feduccia's article provoked...
Prum, R. O. 2003. Are current critiques of the theropod origin of birds science? Rebuttal to Feduccia (2002). The Auk 120, 550-561.
Let me add that - contrary to the view promoted by Feduccia and colleagues - there is not a fundamental 'ornithology vs palaeontology' dichotomy on the issue of bird origins. Most (in fact, virtually all) of the ornithologists I know are both familiar with the evidence for bird origins, and in agreement with the derivation of birds from other theropods. However, it's only the ones who work on 'deep phylogeny' that ever need to comment on it: ornithologists who have supported the dinosaurian origin of birds include Bradley Livezey, Richard Zusi, Gerald Mayr, Richard Prum, and Julia Clarke.
I need to point out that feathers do not make a bird. It was an older development and was not used for flight. It's most likely an advantage for temperature control in a very hot planet with cold nights. Feathers are older than warm blooded. It was the modifications like wishbone and wings with flight feathers allowed flight, but obvious most dinosaurs not birds, only one small theropod became birds, the majority of dinosaurs shared what characteristics to some extent but were not birds.
Ed Pardo:
Friendly advice: you should lurk for a while.
I do go to bird meetings. There aren't a lot of talks specifically about birds being theropods, but there are some. It's not that ornithologists don't know about this. It's just that they don't pay much attention because it doesn't really affect them all that much. Nobody really needs to look more than a few nodes down from the group they study. However, because there are paleontologists who study birds, and because some of them are interested in bird origins too, we get the occasional talk from people like Julian Clarke.
As Darren notes, this all has received a fair amount of coverage in the Auk, which is the major ornithology journal. I should add that Rick Prum replied to Feduccia's cited article and demololished him pretty well: Prum, R. O. 2003. Are current critiques of the theropod origin of birds science? Rebuttal to Feduccia (2002). Auk 120:550-561.
Whoops. That's what I get for skimming. I see now that Darren already cited Rick's response. Sorry.
Julia. Sorry again.
Sven DiMilo
Re: "you should lurk for a while."
When do you think I should pounce then? lol
"only"... "more"... "primarily"...
I can grant you all that, and my point still stands: if you don't know any fossils, some conclusions will appear to be most parsimonious when they aren't, and often several conclusions will appear to be equally most parsimonious when in fact known fossils rule some of them out.
I forgot to comment on this the first time round.
Raymond:
Where is that Simpson quote taken from? Is it from his (rather succinctly named) paper 'Fossil penguins'? If so, the precise quote, to be found on page 94, is
But Simpson's paper was published in 1946, and back then his view would have been very much mainstream. It's hardly fair to single him out* as representing prejudiced orthodoxy, especially as he was a mammalogist first and foremost, rather than a 'dinosaurologist'.
* As Adrian Desmond did, in passing, in his 1975 book The Hot-blooded Dinosaurs.
Simpson, incidentally, while being a specialist on fossil mammals, also had a deep and abiding interest in penguins. He included in his 1946 paper a lengthy criticism of the idea that the ancestors of penguins were always flightless, and that penguins evolved, independently from all other birds, from some dinosaur-like ancestor*. Simpson - correctly - was of the opinion that penguins are nothing but proper, if strongly modified, modern birds that have evolved from volant ancestors; it was in this context that he made his remarks on the dinosaur - bird similarities being convergences.
* There is much more that could be said about this pretty outlandish hypothesis than I can do here. Perhaps Darren would be so kind as to write a Tet Zoo post about it one day (in his plentiful spare time)...?
Reference:
Simpson, G.G. 1946. Fossil penguins. Bulletin of the American Museum of Natural History 87(1), 1-100.
The idea of endothermic dinosaurs have been refuted since the publication of the book "A cold look at warm-blooded dinosaurs." Think! The largest land mammals extant is the African elephant, and it has huge vascularized ears to help it get rid of excess body heat. Mammoths, OTOH, had tiny ears and thick fur to help them retain body heat, but they lived in a different climate than African elephants. Since the end of the last ice age, mammoths have become extinct. These indisputable facts suggest that large endotherms simply cannot exist in a climate as warm as we are having right now. The Mesozoic was an era marked by even larger land vertebrates than we have now, and the climate was even hotter than it is today. Given these facts, how can, a large endothermic dinosaur survive in a hot climate without suffering heat strokes?
We know that male elephant seals can overheat in a few minutes when they run around or otherwise do battle with other males. Luckily for them, they can run into the water and cool off. The same luxury is not always available for dinosaurs. These are simple facts about animal physiology that are unfortunately overlooked by those who are convinced of a dinosaurian origin of birds. John Ruben happens to be more than just a paleontologist. He is a physiologist, and he is definitely more enlightened about dinosaur physiology than those paleontologists who claim that dinosaurs were endothermic. Besides, as Feduccia points out, the enantiorithine birds were ectotherms, since there are growth rings in their bones. So, even if dinosaurs were endothermic, which would have been maladaptive in a warm Mesozoic climate, their endothermy would not have anything to do with their relationship with the earliest birds.
In sum, it is pretty hilarious what many scientists are willing to believe just so they can claim that birds are descended from dinosaurs. The dinosaurian origin of birds and cladistics are like Helium balloons. Just like real life Helium balloons, they will come crashing down to earth one day. The day that someone, anyone, can ride the dinosaurian origin of birds and or cladistic balloon up the academic ladder is numbered, if they have not already disappeared.
dude, I was pulling for you until juust before that last paragraph kicked in.
Well, I hope the locals descend; I might learn something.
Cal King (comment #82)--
What exactly do you mean by the verb "refute" in your opening sentence? Its older meaning was "to prove false" (so, by definition, a true statement can not be refuted: there can only be unsuccessful ATTEMPTS at refuting it).
It is often used now in the weaker sense of "deny" or "attack".
Anyhow... In the weaker sense, yes: it's still a subject of controversy. In the stronger sense, not yet: the criticisms don't (yet) add up to anything I'd be willing to call a "proof" that dinosaurs were not endothermic. The elephant data you allude to cuts both ways: the African Elephant (which I think isn't much smaller than the Woolly Mammoth-- the really big mammoths, like the Columbian, lived in more temperate climes), after all, is still with us! Very large endothermic dinosaurs might need special "radiator" adaptations, analogous to an elephant's ears, to avoid overheating, but it isn't obvious that they didn't have them. For example: a Sauropod's brain is separated from its body core by a long thin neck. I don't know of any serious evidence (presented by professionals-- my speculation doesn't count!) that this functioned to keep the brain cool, but even the possibility, i.m.h.o., keeps your argument from succeeding as a refutation (in the old sense) of the idea that they were warmblooded.
As to Feduccia and Enantionithine birds... There is a fair bit of evidence (including a recent-- published within the past few weeks-- study of the bone histology of Archeopteryx) that many early birds were physiologically intermediate between poikilothermic reptiles and modern birds. Large dinosaurs, however, would have been "inertial homoiotherms" even without bird or mammal style physiological endothermy. They would thus probably have kept (day and night!) a fairly high body temperature. And this is perhaps the worst news for your argument: non-endothermic animals (reptiles, for example) are also in danger of heat stroke (you can kill alligators by keeping them tethered in the sun), so there is a problem about dinosaur thermal physiology WHETHER OR NOT they were endothermic! Denying their endothermy isn't enough to resolve the problem.
This is an exceptionally poor comparison. Elephant seals are marine animals for the majority of their lives (~80%) with a thick layer of blubber to prevent water from conducting away their body heat. When they're on land the blubber is excessively insulating since air conducts heat about 1/24th as well as water.
Do you know what a sauropod looks like???
The long neck and the long tail create lots of surface for heat to dissipate. Even the legs are longer relative to the body than in elephants (deinotheres probably excepted... go learn what a deinothere is, Google is your friend).
And that's without even mentioning the air-sac system.
We also know that male elephant seals have a very compact body shape and are wrapped in a thick fat layer (see comment 85 for details).
What next? "Consider a spherical cow"?
Ruben and Feduccia are a lot more ignorant than you would suspect (...because you're even more ignorant than them, that's why). Plenty of mammals and very big birds (like moa) have growth rings. You have growth rings in your teeth.
And why, pray tell, would anyone want birds to be dinosaurs that desperately? What do we get from it? Huh?
ROTFL! First, you wouldn't even know a cladistic analysis if it bit you in the proverbial ass. Second, cladistics isn't even necessary to demonstrate that birds are dinosaurs beyond reasonable doubt; it just quantifies the "beyond reasonable doubt" part.
To sum up, Cal, you're like a creationist: you suffer from the Dunning-Kruger effect. You are so ignorant that you don't even know how much knowledge there is out there that you have no idea of.
You're embarrassing. You should get out less and read more.
Hang on a second. Physiology puts an upper limit on growth rates, but that does not mean that growth rates will automatically be at that limit. We humans, for instance, grow a lot more slowly than most mammals, yet our metabolic rates aren't remarkably low.
The comparatively slow growth rates of early birds may have been an advantage in limiting intraspecific competition by allowing individuals of different (ages and therefore) sizes to occupy different ecological niches. The extremely fast growth rates of modern birds have another advantage (they allow sexual maturity to be reached very quickly, resulting in fast reproduction). In different environments, one or the other advantage can be more important.
Also, at the risk of stating the obvious, even if Mesozoic dinosaurs were poikilothermic is no reason that modern birds couldn't be descended from them. It would simply mean that the transition from poikilothermy to homoeothermy (which must have happened at some point, because the basal state for tetrapods as a whole is undoubtedly poikilothermy) happened later than commonly thought.
BANDIT logic:
Claim 1: Dinosaurs couldn't be endothermic.
Claim 2: Early birds were not endothermic, either.
Conclusion: Birds are not dinosaurs
*headdesk*
David:
Really? How much longer are they (in relative terms)?
Don't know by heart, and I don't even know if anyone actually ever measured it (it's mentioned in Paul & Leahy 1994 and/or Paul 1998, I think). However, it's pretty obvious when looking at least at extreme examples like Giraffatitan. Prodeinotherium, too (nice mounted skeleton in the museum in Vienna), has such proportions.
Allen Hazen @84: "the African Elephant (which I think isn't much smaller than the Woolly Mammoth-- the really big mammoths, like the Columbian, lived in more temperate climes".
Yep. The African Elephant is actually comparable in mass to (maybe a little bigger), and taller than, the actual woolly mammoth Mammuthus primigenius. The Columbian got as far south as Central America!
Anyway, elephants are built like a cube, *horrible* for losing heat. Sauropods were much more sensibly designed for thermoregulation...
"Large dinosaurs, however, would have been 'inertial homoiotherms' even without bird or mammal style physiological endothermy. They would thus probably have kept (day and night!) a fairly high body temperature."
WHAT??? I repeat, WHAT????? Well, here we go AGAIN. It seems that no matter how many times the "inertial homoiotherm" hypothesis is killed, it keeps popping up. Bakker killed it, Paul killed it, several others have killed it. It just won't freaking die. All dinosaurs, even enormous examples, were truly endothermic in the manner of mammals and avians. If sauropods were too big to be truly endothermic, then please show me an ectothermic whale.
Oh, and Cal King is a menace to society. But, goshdanggit, David Marjanovic beat to me to all the good stuff.
Michael Erickson--
Thanks for correction to my remark about inertial homoiothermy! I'm happy to accept: I wasn't trying to commit myself TO inert. hom., just trying to make a logical point to Cal King (who I didn't realize was a manace to society): EVEN IF large dinosaurs HADN'T been genuine endotherms, they WOULD have had problems with shedding excess heat, so Cal King's argument (If they had been endotherms they would have died of heat stroke so they weren't endotherms) isn't a strong argument for dinosaur non-endothermy.
David Marjanovic--
As to what "we" get from the BAD hypothesis, it depends on whether you LIKE dinosaurs: (one of?) the first semi-popular article(s) about the dinosaur origins of birds, in "Scientific American" in very late 1960s or 1970s, ended by giving, as an additional reason for reclassifying amniotes into three classes, Reptilia, Mammalia and Dinosauria, that it would allow those who love dinosaurs to enjoy the thought that they weren't extinct after all, but singining in the trees outside.
Your welcome Allen! Hopefully I didn't come off too harsh - I was just trying to make a point.
Oh, and "menace to society" was a joke.
so you're asserting that non-avian dinosaurs did not become birds. Well you obviously know that "non-avian" implies: not relating to birds. I didn't have the time to read past the first couple of paragraphs, but why do you need to specify that non-avian dinosaurs did not become birds? Seems tautologous to me.
Thomas MacKow--
No tautology here, because (by the conventions of paleontological usage, which may not be obvius if you look up "avian" in a general dictionary: words often given a specialized sense in specialized disciplines) "non-avian dinosaur" is being used to mean "dinosaur which is not itself a bird," leaving open the question of howclosely related to birds it is.
If you read Darren's post carefully, you'll see that he is actually defending the idea that birds are descended from certain non-avian dinosaurs (and so, in a "genealogocal" sense, ARE dinosaurs) against what he thinks are badly-reasoned criticisms.
That's a crappy way to do it. Assertion + appeal to authority (without specific citation) is weak sauce.
Your problem with the concept of inertial homeothermy is what, exactly?
@ Sven Dimilo:
What? My "problem" with the concept of inertial homeothermy is that it has been killed by several workers and yet the hypothesis is still toted around as if it is viable. I made that quite clear. If you want citations, well here:
Bakker, Robert T. (1986). The Dinosaur Heresies. New York: Kensington Publishing.
Paul, G.S., and Leahy, G.D. (1994). Terramegathermy in the time of the titans: Restoring the metabolics of colossal dinosaurs. Paleontol. Soc. Spec. Publ. 7, 177-198
And these aren't the only ones.
If anything is "crappy weak sauce", I would have to argue that it's your comment. Sorry.
Inertial homeothermy doesn't generate ATP by itself.
Does the BAND contention that dromaeosaurids are not dinosaurs mean that they have now become DAND - Dinosaurs are not Dinosaurs? Seems like the kind of logic that would appeal to them ...
MANIAC â Maniraptorans Are Not In Actuality Coelurosaurs. Courtesy of Mickey Mortimer.
This news is a month old, but physorg has an article about a commentary in PNAS by Ruben.
That article is rather embarrassing. It takes every argument from Ruben's ignorance at face value.
First off, I would like to congratulate Darren for exemplifying how to deal with a differing position with integrity and respect. He pointed out flaws in the arguments and, while he questioned their honesty for given reasons, he did so civilly.
Some of the commentors could learn from him. I am fully in agreement with Darren and was actually driven into grad school by my distaste for Ruben et al.'s publications. But calling anyone who voices disagreement stupid, ignorant, and a menace to society does nothing to help your cause and makes you look less intelligent than the person you are arguing against. I say this because people might want to think about this before launching into a diatribe against other people, thereby reinforcing the common fallacy that there is little difference between religious and scientific hardliners.
While I disagree with Jackson on BAD and BAND, he does make some valid points, regardless what the mocking posts in response claimed. Similarity does not in fact show direction of descent by itself. That is no more than phenetics. It is the PATTERN of similarities across many species that shows descent. Likewise, too many people take cladistics far too much on faith. Cladistics is an excellent tool, but has its own limitations and assumptions that many workers fail to appreciate. We need papers like James and Pourtless (even though I think they are wrong) to make us re-examine our thoughts and data. The effort some took to thoroughly debunk the paper at least made those people think about it in depth, which is good. I should clarify here that I am referring to papers which have as their goal of testing assumptions and looking at the support for established ideas with a fresh look (which is not exactly what J&P did, but was what they were purportedly attempting to do). We don't have time to do this all the time or even much of the time, but we do need to sit back occasionally and seriously ponder do we really know what we think we know because sometimes it turns out we are wrong.
Ok, enough of my soapbox. There are so many juicy points I would like to make but don't have the time, so I'll just make three: if all science worked by Popperian rules, nothing would get done. We would never eat because we can't test the toxicity of all our food. At some point you have to go with the odds. Occam's Razor and Parsimony are rules of thumb, philosophical stances, and as good as they are, are not Laws of Nature and as such, by themselves, do not denote truth as some people tend to forget. It is good to keep this in mind. Cal: if endothermy is so problematic in hot climates, why are all the multi-ton animals in living history endotherms? The largest hot clime animal I am aware of is the Namibian elephant and as previously mentioned, they suck at dumping excess heat. All the large ectotherms are at least semi-aquatic. Something to think about. All the physiology by Ruben, Spotillo, Paladino, and Dodson have some serious flaws. Don't have the refs handy, but G.S. Paul has a nice discussion about this, early 90s I think.
Sorry for the book, if I resist speaking too long, I tend to spew when I do.
I happen to live in a community where someone once thought it would be nice to build nesting boxes to encourage Canada geese to live year-round. They have been fruitful and multiplied, and we are now plagued with too many of them. Every time a gaggle of them walks into the street as if they own the place, confident that we humans will stop and allow them to cross on foot, I am utterly convinced that they evolved from dinosaurs. They still behave as if they were ten feet tall and lords of the earth.
How something is said doesn't change what is said. Commonly the biggest and most offensive nonsense is carried by the most soothing words.
Yes, and? Did anyone dispute that?
Check out comment 51 and then tell us what that stomach-cramping failure of peer-review can make us reexamine.
"Make"???
Did you seriously believe nobody had thought about that in depth before?
To the contrary. The fact that so many people have done that is why it was so easy to write the refutations so fast!
That's where parsimony comes in; it tells you the odds.
Occam's Razor is the principle of parsimony.
That, my friend, is a pretty serious accusation about "some people". In fact, it's an example of what I said at the top of this comment.
Hypotheses about sister-group relationships cannot be falsified (the fossil record is incomplete, so absence of predicted fossils isn't disproof; there are no perfect characters, so we can't point to any predicted character state change and say "that's impossible"). Parsimony is all we have. So we use it.
As far as I can see, the scientific method doesn't even consist of anything but falsification and parsimony! Even methodological naturalism is a parsimony argument.
1994 (with Guy Leahy) and 1998.
There is an alternative to the dino to bird theory.
See here:
http://pterosaurnet.blogspot.com/
Embarrassing for the author who, laughably, pretends to have a doctorate. Painful to read. One argument from ignorance after another. Quote-mining like a creationist... again, it's painful.
Reading MarjanoviÄ is painful.
Instead of posting something constructive, he repeats the old standby cliches. And thinks that these tired old cliches are clever. If he had some actual criticism he would have given it. But we should not hold our breath waiting for that.
Dear 'Anonymous', David M is only saying it like it is. Your site is a total joke. I don't think you've understood any of the criticisms that have been put at your incorrect idea.
I did, above (in this thread). I'd only need to repeat it. Besides, I have a thesis to finish till June 30th.
Do you even understand what it makes you look like that you cite Feduccia as an authority? Like someone who has no idea of the scientific literature and of vertebrate anatomy, that's what.
DPerea.
The site http://pterosaurnet.blogspot.com/
contains extensive and numerous in-context quotes of peer reviewed research by such people as Unwin, Naish, Peters, Hone, Padian, and others. If there is a joke it is their joke on us.
Mr Anonymous, your site is a total joke because you are doing the same thing you were doing here at Tetrapod Zoology. Relying on one or two superficial or primitively shared anatomic features to somehow determine relatedness. Do you not understand that the scientists who have worked on archosaur phylogeny have used lists of huge number of detailed features ? Also, using Wikipedia as a primary source and displaying complete ignorance of the technical literature does not exactly impress. Do you understand what "Quote mining" is?
Science uses facts, not quotes. Evidence, not opinions. Science is not about people, it's about hypotheses and data.
The very fact that you rely on quotes instead of evidence tells me your blog is a waste of time -- time I lack, as mentioned.
Of course, Wikipedia has a good article on quote mining. You should check it out...
If anyone wants to make a claim about quote-mining at
http://pterosaurnet.blogspot.com/
then back it up.
I am not interested in your excuses.
Priorities. I have two manuscripts and a bit of other stuff to write till June 30th; I simply can't do your own homework for you.
MarjanoviÄ has time to post false slanders about quote mining but does not back the slander up.
And DPerae has not backed up his slanders either.
What a joke you guys are.
I will say again:
The site http://pterosaurnet.blogspot.com/
contains extensive and numerous in-context quotes of peer reviewed research by such people as Unwin, Naish, Peters, Hone, Padian, and others. If there is a joke it is their joke on us.
This is simply getting ridiculous. And downright rude.
Anonymous selectively cherry-picks traits that are shared between pterosaurs and birds, while willfully ignoring the vast similarities between birds and other theropod dinosaurs. Having been previously confronted with evidence in other comments, he now chooses to resort to Peter Mihalda-esque insults while still failing to show conclusive evidence for his ideas. And calling himself a "doctor" on his blog is nothing short of being downright fraudulent.
I would call for you to be banned because this is obviously going nowhere, you are oblivious to reason and all attempts to show where you have gone wrong have not worked. But I would rather have Darren make that decision.
If I were a researcher whose work had been misused by you, I would be rightfully livid.
Besides, we have people doing actual research, examining fossil specimens, creating computer models, carrying out experiments. If you are so adamant about your ideas, please do us a favour and go to the museums, look at all the bird, theropod and pterosaur specimens for yourself, and publish something. If you have the time to cherry-pick Wikipedia articles and scientific papers for remarks purporting to support your view, tirelessly leave non-answers to our comments, and if you are indeed a "doctor" as you claim, then you definitely have the time to do some actual first-hand research.
Take your ideas to the Dinosaur Mailing List and Vert Paleo and see how they stand up to the scrutiny of even more knowledgeable people.
I agree wholeheartedly with Hai-Ren and have said on previous occasions why Jack's argument can be dismissed in entirety. For some reason he persists with his arguments and ignores all the criticisms (seriously, what is it with people who hold fringe views - why do they insist that they must be right when they clearly understand little of the subject they're meddling with, and when a vast amount of data contradicts their pet hypotheses?). Jack, I will say again...
------------------
Jack - since April 14th you've posted 30 comments here. You show no indication of understanding the counter-arguments to your proposal, or of giving up on an idea that is clearly not in the least bit parsimonious. Please stop now - I am closing comments on this article. Please take away the following points...
-- If organisms (like pterodactyloid pterosaurs and birds) share anatomical characters, that might be because those characters are widespread within ornithodirans, within archosaurs, or even within diapsids or reptiles or amniotes. You need to understand the difference between 'primitive' and 'derived' characters.
-- If organisms (like pterodactyloid pterosaurs and birds) share superficially similar characters (like toothless rostra), that might be because those two groups have convergently evolved similar solutions to similar problems. In this case, comparison of early forms with more advanced ones shows that convergence is indeed the correct interpretation (viz, advanced birds and advanced pterosaurs both share toothless rostra, but primitive birds and primitive pterosaurs have teeth).
-- Because animals are complicated objects that are composed of hundreds of anatomical components, it is not satisfactory to use one or two superficially similar characters to imply a relationship: you need to analyse tens or hundreds (or more) of such features. This is now routine among people who study phylogeny.
-- A substantial literature shows that birds are maniraptoran theropod dinosaurs: this is because birds share numerous derived anatomical characters with other theropods. In turn, theropods are saurischians, and saurischians are dinosaurs.
-- You cannot claim on the one hand to have read the literature, and then say that you are not aware of the literature concerned. At the very least, you need to be familiar with Gauthier (1986), Holtz (2000) and Ostrom (1976). Pterosaurs do not have a close relationship with birds: birds and pterosaurs do not share any derived characters not seen in other ornithodirans, and pterosaurs lack the characters that might place them within Dinosauria, Saurischia, Theropoda or Maniraptora.
Refs - -
Gauthier, J. 1986. Saurischian monophyly and the origin of birds. Memoirs of the California Academy of Science 8, 1-55.
Holtz, T. R. 2000. A new phylogeny of the carnivorous dinosaurs. Gaia 15, 5-61.
Ostrom, J. H. 1976. Archaeopteryx and the origin of birds. Biological Journal of the Linnean Society 8, 91-182.
------------------
Jack claims that no-one offers any substantial response to his 'birds are pterosaurs' comments. Clearly this is not true: my response above shows why his approach is so flawed (sorry if that sounds arrogant).
On another matter, Hai-Ren is the third person to recommend that I ban Jack from Tet Zoo. I prefer not to ban people for several reasons, and so far I don't feel that Jack deserves this (Peter Mihalda was banned because he didn't just promote 'non-standard' views, but combined his commenting with a high degree of aggression, rudeness, and strong, blatant racism. He is flat-out offensive). But - be warned, Jack. You ARE guily of quote-mining and you still show no understanding of the differences between shared primitive characters, shared derived characters and convergences. Your hypothesis fails on all counts and is not worthy of any consideration.
Darren:
What I don't get is why there seems to be so many people who hold fringe views on this particular subject. I can understand why people get emotional over the question of human origins, but why does the question of bird origins arouse such amounts of sentiment? Is there some paleontologically interested psychologist out there who could shed light on this peculiar phenomenon?
Hey, PM could start posting comments on Jack's blog, couldn't he...?
Then why do all of these people disagree with you?
All of them agree with us (that Naish guy in particular has just told you so in person) and disagree with you that birds are not descended from pterosaurs, but from dinosaurs. You pretend the opposite, and take short quotes from these very people out of context to back your false claim up. This is the very definition of quote-mining.
Don't you even notice that that's what you're doing!?!
I second the suggestion that you join the Dinosaur Mailing List. Here are the instructions for how to do that.
More people claiming quote mining. But nobody backing it up.
Don't you even notice that that's what you're doing!?!
Jack - (1) stop signing your comments as 'Anonymous', (2) 'quote mining' is when you take a quote (e.g., all those many, many quotes taken from wikipedia on your site) and then use it out of context (e.g., to erroneously support your view that birds and pterosaurs are uncannily similar). David already said this. You should stop doing it: it is a dirty little trick, so transparent that it never works. I note you quote my work in places; just for the record, you have succeeded in abusing the quote by using it out of context, and are hence a true quote-miner in the worse use of the term (e.g., you use it to say that pterosaur crests are somehow similar to the feather crests of cockatoos. That's just laughable).
I will say again:
"More people claiming quote mining. But nobody backing it up.
Don't you even notice that that's what you're doing!?!"
Show where I have used a quote out of context.
Or stop with that slander.
See comment 125. And the accusations of quote mining are not 'slander'. This is my last comment in this thread; all you do is repeat yourself.
A false accusation of quote mining is slander.
Show where I have used a quote out of context.
Or stop with that slander.
By the way. When I quote from researchers' evidence, I am not claiming that they agree with my position. They do not. But their evidence supports what I am saying.
That is what is important. And that is not quote mining.
But arguing about this is a waste of time.
Just back up your claim or stop with the slander.
Even better. Try to address the actual points I have made.
And there are many of them.
It is at this time that I recall the various stereotypes posted on the Flame Warriors page, and find the following most apt for our dear friend:
Ferrous Cranus
Tireless Rebutter
and a little dash of Loopy
"If organisms (like pterodactyloid pterosaurs and birds) share superficially similar characters (like toothless rostra), that might be because those two groups have convergently evolved similar solutions to similar problems. In this case, comparison of early forms with more advanced ones shows that convergence is indeed the correct interpretation (viz, advanced birds and advanced pterosaurs both share toothless rostra, but primitive birds and primitive pterosaurs have teeth)."
Note the use of the words "primitive birds". By this you mean non-avian theropods. Because that is your theory.
Here are the simple facts:
Advanced pterosaurs had toothless rostra (as you acknowledge). Modern (what you call "advanced") birds have toothless rostra (as you acknowledge).
Concerning teeth, the evidence supports the idea that advanced pterosaurs developed into modern birds. The evidence does not support the idea that non-avian theropods developed into modern birds.
There is no need for the idea of convergence.
"Because animals are complicated objects that are composed of hundreds of anatomical components, it is not satisfactory to use one or two superficially similar characters to imply a relationship: you need to analyse tens or hundreds (or more) of such features. This is now routine among people who study phylogeny."
On http://pterosaurnet.blogspot.com/ dozens of similar characters are analyzed.
People can stop making the absurd claim that I have analyzed "one or two superficially similar characters".
No, Dr. Naish does not mean non-bird theropods when he says primitive birds. Turns out that most bird lineages had teeth, not vice versa. Unless you don't think Shenzhouraptor, most enantiornithines, hesperornithines, and Ichthyornis were birds.
Also, you keep claiming there's "no need for the idea of convergence" for traits shared by some pterosaurs and some birds, but you yourself are implying the parasagittal stance, hinge-like ankle joint, obligate bipedality, loss of digit V, furcula, loss of digit IV, feathers, enlarged sternum, semilunate carpal, laterally-oriented shoulder joint, backwards-pointing pubis, distally-placed metatarsal I, and proximally-mobile caudals shared between birds and non-bird dinosaurs are all convergent. Why?
Albertonykus.
You obviously have not read the site
http://pterosaurnet.blogspot.com/
Your questions are answered there.
I am not repeating them here one by one.
Mr Anonymous: I find your assumption that all members of the scientific community are male to be offensive. For your idea, I still can not accept that a person can argue about a subject that they known so little of. Your idea is what we call "on the fringes" and you are relying on your ignorance of the facts, not knowledge of them.
A massive literature shows beyond doubt that pterosaurs are close relatives of dinosaurs within Ornithodira, while birds are nested among the theropod dinosaurs. You should stop posting, you are just making yourself look increasingly idiotic. One more thing - science is not abot being stubborn and blinkered but about assessing evidence and coming to the best supported conclusion.
Come back when you've got four hundred. That's the size range of phylogenetic analyses of bird origins published in the last 10 years.
If you look at this one character alone, yes.
Now let's look at a couple more: You're saying the wing membrane and the entire fourth finger disappeared, the forearm and the palm of the hand rearranged themselves drastically, the sprawling hindlimbs (which were involved in the wing apparatus) transformed themselves into vertical legs for running or grasping, the ribcage and shoulder girdle were completely rearranged from scratch, and feathers appeared, complete with differentiation into wing and tail feathers. You are postulating insane amounts of convergence between ancient and modern birds. And then you blithely claim your hypothesis doesn't require "the idea of convergence"???
Seriously?
BTW, please do try to find out what the technical term "theory" means in science. You used it wrongly.
Incidentally, toothlessness evolved several times within birds alone: Confuciusornithidae, Gobipteryx, Archaeorhynchus, Neornithes... several others are almost toothless, and other stages of reduction occur as well. Teeth are also readily lost elsewhere among theropods (derived ornithomimosaurs, derived oviraptorosaurs), elsewhere among archosaurs (Lotosaurus, Shuvosauridae), elsewhere among sauropsids (Ankylosphenodon IIRC, derived turtles), and so on and so forth. It's rather silly to insist that precisely this character shouldn't evolve convergently just one more time.
This is funny.
The first requirement:
"you need to analyse tens or hundreds (or more) of such features.'
So I analyze tens. I meet the requirement. And then that is not enough.
(I saw that excuse coming).
But I know you can think of many more excuses rather than making the effort to actually address the points I have made.
But that is okay.
Anonymous: Analysing characters = not synonymous with taking quotes from wikipedia!! I think parsimony analysis was intended. You truly are waste of time, stop commenting on tetrapod zoology please.
Daniella.
I do not demand you stop posting. I find your demands that I stop posting to be offensive.
I find your grotesque ignorance of the scientific process offensive. Juxtaposing quotes from wikipedia is a joke, your idea is a joke, your comments read like jokes. Go and read the literature and look at lots of fossils before speaking again.
Daniella.
The site http://pterosaurnet.blogspot.com/
contains extensive and numerous in-context quotes of peer reviewed research by such people as Unwin, Naish, Peters, Hone, Padian, and others. If there is a joke it is their joke on us.
By the way. Two thirds of the quotes on
http://pterosaurnet.blogspot.com/
are from sources other than wikipedia.
Your grotesque ignorance of what you are talking about is offensive.
That is all I will say to you.
Anonymous, I will say one last thing. Debates do not happen, hypotheses are not formed or tested, by picking quotes. That. Is. Not. How. It. Is. Done. That is what creationist idiots do. But not people interested in testing scientific hypotheses.
I am assuming that you are less than 15 years old so I apologise if any of this hurts your feelings.
I'm glad Daniella got in his/her final childish insult. I know that is important to him/her.
But I am disappointed that people here have not had the interest to review the pterosaur-to-bird idea that I have posted about.
It is interesting to see how close pterosaurs are to modern birds compared to how close non-avian dinosaurs are to modern birds.
That comparison can be done in a systematic, unemotional way. And that is what I have done at:
http://pterosaurnet.blogspot.com/
Jack, wait till July. Then I'll have time to address your arguments from ignorance one by one.
In the meantime, look up the Dunning-Kruger effect already, because you suffer from it bigtime.
Oh, and... isn't it rather obvious that Daniella is of the female persuasion?
On every blog and discussion group, someone thinks they are clever by mentioning the Dunning-Kruger effect.
And they attribute it to anyone they disagree with (not just me).
It is sad.
I have seen every slur and every excuse.
It looks like you allow insults against me but not my response to them.
Shame on you.
[from Darren: no, not so. The system has been treating your comments as spam.]