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Re: The ACTUAL flying Microraptor paper in PNAS

I finally read the paper.

Right below the author addresses, it says "Edited by Alan Feduccia". The bottom right corner of the first page says "This article is a PNAS Direct Submission. A. F. is a guest editor invited by the Editorial Board." Now, "direct submission" means it was peer-reviewed (judging from the instructions to authors: http://www.pnas.org/site/misc/iforc.shtml), but, while the acknowledgments list a lot of people, nobody is mentioned to have reviewed the manuscript...

As the abstract describes, the decision between the flat pose and the biplane one (legs vertical and crouched, metatarsal feathers sticking out sideways, which would explain why they're so extremely asymmetrical) was made based on which one makes a better glider. This presupposes that *Microraptor* was a glider, _and_ that it was anatomically able to assume both positions.

The abstract and the supp. inf. (1st page) say that sprawling up to ~ 70° from vertical was possible -- but this assertion isn't tested anywhere in the paper or the supplementary information. The authors merely mention that they looked at "several hundred specimens" and ">100 additional specimens" (p. 2972) or ">300 microraptorians" and "hundreds of other deinonychosaurians with plumage and feathered feet along with thousands of Chinese Mesozoic birds" (1st page of supp. inf.), but don't provide any illustration, any description of what the hip joint looks like, any mention of diagenesis, anything -- only two specimen numbers are given in the supp. inf., but those specimens were used for reconstructing the shape of the plumage; the hip joint isn't mentioned with them. The text further says (p. 2974) that its hip joint prevented *Microraptor* from raising its legs _above_ vertical -- now that is not surprising, so I understand why it isn't backed up with any reference to specimens, but that's all that's said about the hip joint in the entire paper.

As has already been pointed out, the first page implies continuity between the plesiomorphic sprawling posture of archosauriforms and the highly derived sprawling posture of foot-propelled diving birds (incidentally, this includes the hesperornithiforms which aren't mentioned even though the third author, Larry D. Martin, has worked on them). This, laddies and gentlewomen, is a rhetorical trick. It is not science.

As has also been pointed out, the claimed absence of antitrochanter and supracetabular shelf in nonavian eumaniraptorans is wrong. But lack of familiarity with the relevant literature isn't a surprise with these people.

The assertions at the end (that *M.* was able to climb tree trunks and basically unable to walk) have likewise been addressed. They simply don't follow from the rest of the paper, and aren't accompanied by a citation either.

Fig. S1 shows a model of a *Microraptor* skeleton with legs sprawled 90° from vertical -- the pose that the SVP meeting presentation by Burnham et al. 2008 had claimed in all seriousness, but that the text of the present paper does _not_ claim anymore. Unfortunately the resolution of that photo isn't good enough to say anything about whether the hip joint is painfully dislocated. But anyway, have a look at the foot, and laugh. The metatarsus is twisted by 90° so its plantar side faces ventrally instead of caudally! Alexander et al. took the ankle apart and put it back together in an utterly laughable position! :-D This was kept in the model, as shown in fig. S4.

In the same photo, the 1st toe opposes the others, and the claw on the 2nd toe is way too small while the toe as a whole is too long, as the photo of the holotype (fig. S2) shows.

The text says at least some specimens support the claim that the tail fan was V-shaped. Then how did fig. S4 happen, and why does it claim to show "the actual size and shape of feather impressions on fossil specimens"?

(Never mind that the feathers aren't preserved as impressions.)

Three sad options: either this paper wasn't peer-reviewed (in which case something is wrong with "direct submission"); or it was, and the referees recommended publication without changes to the points mentioned above, in which case it's a rather spectacular failure of peer review -- perhaps all reviewers thought the support for all those strange claims was given in the supp. inf. and didn't bother reading it --; or the referees recommended against publication (maybe that's why they're not thanked???), but the guest editor accepted the manuscript anyway.

All three are disturbingly uncharitable. Can someone suggest more possibilities of what could have happened?