The Aerosteon saga, Part 3: True and false ad hominems

October 31, 2008

If you’re new to this thread, here’s a minimal reading list, in chronological order. I say ‘minimal’ because all of the relevant papers are freely available, and therefore all of the factual claims are easy to check.

The last is Paul Sereno’s response to my criticism of the Aerosteon paper. Here’s the full text, with my comments. Please go read the un-commented version at PLoS first, and see if you find it compelling.

In two trackbacks to our paper, Matt Wedel offers a misleading, longwinded, ad hominen critique of this paper on the new theropod dinosaur, Aerosteon riocoloradensis, and the significance of its pneumatic features.

There is a widespread misconception that if you say something unflattering about someone, that constitutes an ad hominem argument. In fact, an ad hominem argument has a specific form (quoted from Wikipedia):

  1. Person A makes claim X
  2. There is something objectionable about Person A
  3. Therefore claim X is false

If you actually read my critique, you’ll see that the form of my argument was more like:

  1. Sereno et al. claim X
  2. Claim X is misleading and easily falsifiable
  3. Sereno et al. probably claimed that X is true because it would support their hypothesis Y

I will not deny that I publicly speculated about the motivations of Sereno et al. (2008). Many of the arguments used in that paper are very difficult to explain unless Sereno et al. were trying to systematically discredit or suppress previous work (either by citing it misleadingly or not citing it at all). If you disagree, that’s fine. But don’t expect anyone to take your disagreement seriously unless you can back it up with evidence.

Anyway, remember what a real ad hominem argument looks like. We’ll see one later on.

Some personalized aspects of the commentary and erroneous claims push the limits of the “good practice” guidelines posted for commentary in this journal (

Here’s the last line of the good practice guidelines: “PLoS is the final arbiter of the suitability of content for inclusion in the PLoS Web sites.” In short, the guidelines are for commentary posted at PLoS, not about PLoS papers. A trackback is just a reciprocal hyperlink to material elsewhere on the ‘net–for example, a private blog, like this one. If the folks at PLoS don’t like the incoming links, they can always delete them and block my access.

And, hey, Darren put a trackback with his own critical review of the Aerosteon paper, but he doesn’t get mentioned at all here. Where’s the love?

Also, I’m curious to see which of my claims were erroneous. Presumably a fact-based rebuttal will be forthcoming, since Sereno does not engage my “misleading, longwinded” critique on a single point.

In this paper, we did our best to:

1) Present the pneumatic evidence as clearly as possible (Figs. 4-16).

2) Cite the literature thoroughly and fairly (95 citations).

3) Critique available hypotheses for the evolution of avian intrathoracic air sacs and respiratory mechanics.

4) Outline more clearly in tabular format our osteological correlates (Table 4).

5) Diagram more specifically particular stages as supported by current fossil evidence (Fig. 17).

In the short first trackback, Wedel outlines and agrees with all of the main points of the paper.

False. I said that the morphological description was mostly (not entirely) accurate. It’s the rest of the paper I have issues with, as I clearly and patiently explained. In fact, in the first trackback I hardly dealt with the Aerosteon paper at all; as the title suggests, I was laying out introductory and background material.

He then digresses to critique earlier papers and ends by explaining what “we’ve been up to”, referring to papers by himself, Pat O’Connor and Leon Claessens—research we cited many times in the paper, both positively for evidence and in critique.

…and other research they cited misleadingly or did not cite despite its relevance, as I’ve documented, and as Darren has further shown. Simply counting up cited references (ooh! 95!) does not demonstrate that previous work is cited “thoroughly and fairly”. I note that, in keeping with the rest of his comment, Sereno does not respond to any of my actual critiques, or try to defend the misleading citations.

Much of the personalized negativity of the second trackback is clearly generated by Wedel’s sense that the press unfairly aggrandized our work compared to theirs, which we somehow slighted and miscited.

Well, well, lots to dissect here.

First, they only address the “personalized negativity”. What about all the evidence? Not only is it not rebutted–it’s not even mentioned. Maybe they have an exhaustive, evidence-laden rebuttal lined up for that later. I honestly hope so.

Second, check out the form here:

  1. Wedel makes claim X
  2. But he’s jealous of our media exposure
  3. Therefore claim X is false

Textbook ad hom right here. Which is pretty ironic, since it’s the first pure example of the genre that has cropped up in this discussion so far, and it appears in a commentary that accuses me of ad hominem attacks.

Third, there is no question that Sereno made misleading statements to the media about the significance of Aerosteon. For example, when he claimed that it represented the first evidence of dinosaur sacs . . . about 150 years too late. That’s an easily verifiable fact, not an example of “personalized negativity”.

UPDATE: The “first evidence” thing was apparently hyperbole on the part of an underinformed journalist. At least, it’s not in the official press release, and Sereno denies ever saying it. He is right that one should never attribute to a possibly overzealous scientist what can be laid at the door of bad reporting–I’ve had some experience of this problem myself.

I wish now that I’d never brought up the misleading statements in the press. That opened me up to the ridiculous charge of being motivated by jealousy, and it’s quite beside the point. All of the important problems with the Aerosteon paper are scientific, not popular.

Fourth, I have no problem with other people working on pneumaticity and air sacs. Quite the contrary–it’s a big field and there’s plenty of work to be done. The more the merrier I say. I was very happy when Daniela Schwarz-Wings started working on pneumaticity in sauropods–her papers (including a new one out this week; congrats!) are thoughtful, innovative, and heck, just flat gorgeous:

Cervical diverticula in Brachiosaurus, from Daniela’s new paper (the original is a movie!).

So it doesn’t bother me that Sereno et al. (2008) wrote a paper about pneumaticity. What bothers me is the pervasive distortion of previous work and basic anatomy. I’m against that no matter what the subject.

Fifth, if anyone is curious about how it feels to languish in total obscurity, utterly ignored by the mainstream media, hoping against hope that someday I’ll make a valuable scientific contribution: I’m doing just fine, thanks. Fame’s a weed, repute a slow-growing oak, and I’m aiming for bark and acorns.

Neither we nor Pat O’Connor (pers. comm.) feel that personalized, ad hominem blogs like Wedel’s advance scientific understanding or enhance collegiality.

Hmm. I think it’s a bit pessimistic to say that my critiques didn’t advance scientific understanding. Certainly I’ve had a lot of people thank me for untangling the paper trail and showing what McLelland and others actually said about avian anatomy. A matter of taste, I suppose–although if Sereno was already familiar with what McLelland said, it’s odd that he got the cited information exactly backward.

Just for the record, I didn’t consult with Pat O’Connor or Leon Claessens about my critiques. We’re all big boys now, we can all speak for ourselves, and any fallout from SV-POW! will hopefully fall right where it belongs: on me. It’s not like I’m hiding.

As for collegiality . . . here’s where I stand:

  • As scientists we have a duty to obsessively document all previous relevant work and give credit where it is due, especially in cases where someone else got to the right answer first. I can’t speak for anyone else, but I got a real kick out of discovering that Heber Longman had worked out the basic dichotomy in internal structures of sauropod vertebrae decades before anyone else. And I made sure people knew about it (4th page here). I’ve always gratefully given credit to the giants upon whose shoulders I struggle to stand–among them, Owen, Seeley, Cope, Marsh, Longman, Janensch, Britt, Witmer, Wilson, Sereno (that’s right–he has done good and important work), O’Connor, Claessens, and Schwarz-Wings. Go look. Don’t forget to reread the Aerosteon paper while you’re at it. And then–yep, I am going to say it yet again–make up your own mind.
  • When authors engage in misleading citation and muddle the historical record–for example, by citing a paper in support of argument X when the cited paper actually states the precise opposite–people who are familiar  with the literature have a duty to explain how that literature is being misused. Collegiality doesn’t mean that we all keep our mouths shut no matter what (there’s a related word for doing that, and it also starts with a ‘c’). Sometimes we have to speak up and defend collegiality itself.
  • If someone brings a fact-based critique against your work, rebut them with facts or not at all. Calling names just makes you look weak and gives the impression that you have no factual case to pursue. My critique of the Aerosteon paper is “longwinded” only because it is so thoroughly documented. Sereno tries to paint it as a content-free exercise in pique–which is a pretty fair description of his own response. The irony could hardly be any richer.

I’m stuffed.

(On irony, not evidence. If anyone has any of the latter to bring against my critiques, I’ll be very happy to see it.)

20 Responses to “The Aerosteon saga, Part 3: True and false ad hominems”

  1. David Marjanović Says:

    In fact, an ad hominem argument has a specific form (quoted from Wikipedia):

    Person A makes claim X
    There is something objectionable about Person A
    Therefore claim X is false

    I’ll hijack this opportunity to mention the oft-forgotten fact that the opposite is an ad hominem argument, too:

    Person A makes claim X
    Person A is a wise master
    Therefore claim X is true or most likely true

  2. Jay Nair Says:

    Minor correction, but no big deal – Longman was Heber Longman (not Herbert).

    But Matt is right, for his time Longman’s sauropod descriptions were amazing detailed and spot on (most of it still is actually) despite the limited material and its preservation, and considering Longman’s own self-taught background.

  3. […] above-mentioned criticisms as “a misleading, ad-hominem critique”, and Matt Wedel has responded to the comment at […]

  4. Matt Wedel Says:

    Minor correction, but no big deal – Longman was Heber Longman (not Herbert).

    Fixed, thanks.

    But Matt is right, for his time Longman’s sauropod descriptions were amazing detailed and spot on (most of it still is actually) despite the limited material and its preservation, and considering Longman’s own self-taught background.

    Longman became one of my heroes when I was working on Sauroposeidon, for just those reasons: he was able to start from relatively lousy material and produce great results just by being observant and thinking carefully. It’s a shame his work is not more widely read.

  5. Zach Miller Says:

    Well, there’s the “response” from Sereno’s camp that I was hoping for, and it seems…empty and dull. One can only hope that a far longer, more detailed rebuttal is forthcoming. Although that’s not really the man’s style, is it. We’re still waiting on monographs for Eoraptor and Herrerasaurus, after all. It’s only been…oh…fifteen years, give or take a few months.

    I fully support Matt on this one. Science is all about pointing out the flaws in other arguments, and he did that responsibly and without parsing words, which I encourage. Sereno’s one of the “hot shots” in this field, but that doesn’t make his works somehow above the law.

  6. Now now Zach, Sereno and Novas monographed Herrerasaurus in 1993. You were obviously thinking of Afrovenator, Cristatu… er… Suchomimus, Baharia… whoops.. Deltadromeus, and ‘Rebbachisaurus’ tamesn… I mean Jobaria. ;)

  7. Zach Miller Says:

    Hey, I wasn’t aware that Herrerasaurus got a monograph! That’s exciting, and now I want to read it. Anyone got a citation?

  8. Mike from Ottawa Says:

    It seems Mr Sereno himself is in violation of this rule from the PLoS ONE guidlines: “Unsupported assertions or statements should be avoided. Comments must be evidence-based, not authority-based.”

  9. Mike from Ottawa Says:

    Am I the only one somewhat disappointed Daniela Schwarz-Wings didn’t go into pterosaur research?

  10. 220mya Says:


    Novas, F. E. 1993. New information on the systematics and postcranial skeleton of Herrerasaurus ischigualastensis (Theropoda: Herrerasauridae) from the Ischigualasto Formation (Upper Triassic) of Argentina. Journal of Vertebrate Paleontology 13:400-423.

    Sereno, P. C. 1993. The pectoral girdle and forelimb of the basal theropod Herrerasaurus ischigualastensis. Journal of Vertebrate Paleontology 13:425-450.

    Sereno, P. C., and F. E. Novas. 1993. The skull and neck of the basal theropod Herrerasaurus ischigualastensis. Journal of Vertebrate Paleontology 13:451-476.

  11. Zach Miller Says:

    Oooohhh. Thanks! Now I’m gonna go bother people for reprints! :-)

  12. Matt Wedel Says:

    If you’re an SVP member, you can get ’em for free through

  13. Mike from Ottawa Says:

    Thought it is almost beside the point, that picture of the Cervical diverticula in Brachiosaurus is an excellent SVPOW. I’ll be off to try to read the paper (gotta get my brain exercised).

  14. Jaime A. Headden Says:

    There is now a response from Paul that seems longer:

  15. Matt Wedel Says:

    Thanks, Jaime, for bringing this to our attention. Couple of interesting bits in there:

    “Wedel is free to be completely convinced (in contrast to at least one of his previous publications) of the close match between pneumaticity in neognaths and the osteological correlates we can observe in saurischians.”

    I. Am. So. Lost. Seriously. In which of my previous publications did I assert that pneumaticity in birds and osteological correlates in dinos don’t match? In my 2003 Paleobiology paper I discussed how continuous pneumatization of the vertebral column might not indicate abdominal air sacs, if diverticula of the cervical sacs were doing everything, but as I explained in Part 2 that was back before O’Connor and Claessens (2005) demolished the all-cervical-all-the-time model. In my 2005 book chapter and 2007 prosauropod paper I discussed the fact that some fossae (those without distinct margins, and those that are only weakly emarginated) are not clearly diagnostic for pneumaticity; if you look in living animals, sometimes those less-distinct fossae are pneumatic, and sometimes they aren’t.

    All of that uncertainty about the indistinct fossae leaves aside the deep, sharp-lipped fossae and foramina leading to internal chambers, which have always been the primary evidence for postcranial pneumaticity in all extinct taxa. Those features are only produced by pneumatic diverticula, so they are prima facie evidence of pneumaticity in the fossil record. I thought I’d hammered that point about as hard as I possibly could, since pretty much everything else there is to say about diverticula and air sacs depends on that inference.

    Who knows, maybe there is something in my perceptual blind spot. If anyone has any idea what he’s referring to, please let me know!

    Then there’s the bit at the end.

    We are of the opinion that personalized, ad hominem blogs like the pair from Wedel do little to advance scientific understanding or enhance collegiality but have the opposite effect.

    Really? If that’s his opinion, it’s curious–and by curious I mean deeply ironic (burp)–that he apparently started a blog to rehash his PLoS ONE comment, which actually was ad hominem. If it’s all dry science, why not put it on PLoS?

    We will not add to that effort by recounting personal information regarding our perceptions of the intentions or actions of others.

    Too late!

    It is totally coincidental, but also totally great, that he would accuse me of being motivated by jealousy over media exposure just a couple of weeks before a nice profile of my research on the History Channel. I guess I just couldn’t wait. ;-)

    We state only the following for the record:

    Ah. Now, what you gotta do is follow the link back to his blog post and read all of this at one go, without my snarky comments inserted. Because when you say you’re NOT going to speculate about motives and then list some dry facts, that’s usually because you feel that the facts themselves will illustrate the misdeed that you are too noble to explicitly describe. So what’s coming?

    1. The exceptional pneumaticity in girdle elements in Aerosteon was initially reported in an abstract in the Journal of Vertebrate Paleontology (Alcober et al., 1998) with details presented in 2005. The material has been available for study since that abstract was published and has been examined by several researchers.

    Yep, nothing to see here.

    2. We prepared a manuscript on Aerosteon for Science early in 2005 that was rejected largely on the basis of one reviewer’s opinion that air sacs could not possibly initially have evolved in non-avian dinosaurs for heat loss (one of the possibilities we regard as plausible and in need of testing as outlined in the paper).

    Okay, Aerosteon was submitted in 2005, but rejected. Interesting backstory, I guess, but the relevance is not yet clear.

    3. Later that year, O’Connor and Claessens (2005) published a Nature paper with a similar focus.

    Whoa! Given the suggestive nature of the opening comments (~ we’re not going to speculate about motives but here are the facts) and the placement of this fact right behind the bit about the Aerosteon paper being rejected by “a single reviewer”, it seems, to me, larding on as many conditionals as I can to avoid being accused of what I’ve already been accused of, that Sereno is implying that either O’Connor or Claessens sunk the earlier Aerosteon manuscript and then rushed their own paper “with a similar focus” into press. I’m not sayin’ for certain that that’s what Sereno is implying, but…he’s not NOT implying that.

    So, just in case anyone else also got that implication, and on the off chance that someone having gotten that implication thought there might be some validity to it, I gotta make with some facts of my own:

    1. Neither Pat O’Connor nor Leon Claessens recommend rejection of the 2005 Aerosteon manuscript. I know that because they didn’t even review it. I also know that because I know who did recommend rejection. It wasn’t me, it wasn’t Kent Sanders or Brooks Britt, and it wasn’t anyone you will guess before the heat death of the universe. Don’t waste your time; the reviewer remains safely anonymous. But it wasn’t Pat or Leon.
    2. Nothing in O’Connor and Claessens (2005) could be construed as having been…influenced…by the rejected Aerosteon paper or the previous abstracts. Pat and Leon were making a case for bird-like air sacs based (1) on vertebral pneumatization, which has a LONG history in the literature, and (2) on the veritable mountain of real live dead birds that they looked at; Sereno et al.’s case depends on appendicular pneumaticity and, uh, citing a couple of papers on birds (incorrectly). Also, if you wanna know who knew what when, you can ILL a copy of Pat’s dissertation from 2003, from which his recent papers were derived. That’s two years before the rejected Aerosteon manuscript he never saw, so unless he had a time machine, any…insinuation…that O’Connor and Claessens (2005) were influenced by Aerosteon is not only false and vile, but contradicted by the laws of physics as we currently understand them.

    I sincerely hope that the extreme criticism of Pat’s and Leon’s work in Sereno et al. (2008) was not motivated by a mistaken perception that Pat and Leon had somehow scooped them.

  16. Matt Wedel Says:

    From Paul Sereno’s blog: “ratites are basal within Neornithes and therefore are stronger than a hummingbird for phylogenetic comparisons.”

    No, they’re not. Look, this is simple: which am I more closely related to, a croc or a chicken? The answer is neither. The line that led to both crocs and chickens branched off the line that led to mammals, neither group is on the mammalian stem (so I don’t share a more recent common ancestor with either one to the exclusion of the other), and therefore I am not more closely related to either one. Or better, I am equally closely related to both through the archosaurian common ancestor.

    Same deal with Aerosteon, ratites, and hummingbirds: the lines that led to Aerosteon and Neornithes diverged back in the Jurassic, neither ratites nor hummingbirds are on the stem leading to Aerosteon, so Aerosteon is equally closely related to ratites and hummingbirds through the common ancestor of Neornithes.

    If you think that ostriches are “closer” to Aerosteon because they’re at the “bottom” of the bird tree, you’re just not thinking clearly. All you have to do is spin the tree 180 degrees at the neornithine node and now hummingbirds are “closer” to Aerosteon on the line leading to ostriches.

    Now, you may argue that ostriches are better for functional comparisons because they have retained more symplesiomorphies with Aerosteon. That’s possible, but debatable, depending on what system you want to discuss. But the idea that ostriches are better on phylogenetic grounds is simply false.

    Sereno et al. (2008) chose the ostrich because it is flightless and has small abdominal air sacs. Both of those traits are homoplastic both across birds and with Aerosteon, so although my hummingbird suggestion was a joke, it is also perfectly valid by the criteria they used (I suppose a flightless hummingbird would have been best).

    Sereno goes on to say, “The point we made concerning the abdominal air sac in nonavian theropods is that it could not possibly have occupied the volume it does in extant avians under the posterior axial column; the articulated preservation of pubes in Aerosteon and posterior dorsal and sacral centra nearly close the pelvic outlet.”

    …and yet the big news is that Aerosteon provides such good evidence for abdominal air sacs. If Aerosteon had abdominal air sacs despite its narrow pelvis, then surely other saurischians might have as well. Also, we could wrangle all day about whether we think that saurischians had enough room for abdominal air sacs; what is more important is that most saurischians have patterns of pneumaticity that are diagnostic for abdominal air sacs.

  17. Zach Miller Says:

    Sereno and his cohorts seem embedded with embitterment. Can there be no peaceful end to this conflict? Perhaps an arm-wrestling match at the next SVP will settle it.

    But seriously, I’m really surprised that Sereno (et al) is continuing this debate. Cognative dissonance is a wonderful thing.

  18. […] has also responded to the criticisms raised by Matt Wedel on a blog. There is plenty of information to dig into, and I hope that all those […]

  19. […] I didn’t get it submitted until last January. I had to forcibly bite my tongue during the Aerosteon saga last fall, when such a big deal was made about the absence of pneumatic hiatuses in non-avian […]

  20. […] of dinosaur palaeontology is probably just as aware of Matt’s series of Aerosteon response articles here on SV-POW! as it would be if he’d put those together into a paper that was published in […]

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