Like Yi qi, the new Ambopteryx does NOT have bat wings

Wang, O’Connor, Xu and Zhou 2019
report on another scasoriopterygid with a ‘styliform’ bone creating a bat-like wing membrane in their imaginations. They named this specimen, Ambopteryx longibrachium (Fig. 1). This would be the second such instance, in their opinion, of a bat-wing bird. You might remember the flap over the first such instance, Yi qi (Fig. 2), which turned out NOT to have as styliform bone, just a displaced ulna on one side, a displaced radius on the other.

Figure 1. Photos and black tracing from Wang et al. 2019. Colors added here. There is no styliform bone on either wing. That is a displaced ulna... again.
Figure 1. Photos and black tracing from Wang et al. 2019. Colors added here. There is no styliform bone on either wing. That is a displaced ulna… again, as the reconstruction at upper left shows.

Well… tracing the elements in color
|reveals no styliform bone. See for yourself (Fig. 1). Again the authors mistook a perfectly good ulna for the invalid and imagined ‘styliform’ bone on the left wing. Turns out Ambopteryx longibrachium has a perfectly normal radius and ulna, just like all of its sisters in the bird clade. The authors do not illustrate a styliform bone on the better articulated right wing. It should have been there, if it was there in life.

Figure x. Closeup of the Ambopteryx forelimb. Here the purported radius + ulna is only the radius after crushing with two quarters of the exposed radius crushed neatly in half giving the impression of a radius + ulna, exactly the same length and without any interosseum space, which never happens in birds.
Figure x. Closeup of the Ambopteryx forelimb. Here the purported radius + ulna is only the radius after crushing with two quarters of the exposed radius crushed neatly in half giving the impression of a radius + ulna, exactly the same length and without any interosseum space, which never happens in birds.

The authors tried to make the extraordinary and implausible ordinary
by introducing another example of their previously invalidated observations. Today’s exercise demonstrates the importance of color tracing and using those tracings, as is, to build reconstructions. Do not freehand! The present notes also demonstrate, once again, just because some discovery is published in Nature, and heralded by major publications (see below) it still might not be true.

Figure 2. Yi qi tracing of the in situ specimen using DGS method and bones rearranged, also using the DGS method, to form a standing and flying Yi qi specimen. Note the lack of a styliform element, here identified as a displaced radius and ulna.

The news media is all over this:
with gorgeous paintings and glorified reports of a mythical creature with a bird body and bat wings. Unfortunately, like the editors and referees at Nature, they, too, were bamboozled by bombast.

www.nationalgeographic.com
www.smithsonianmag.com

Lead author Wang dramatically reported,
“I was frozen when I realized that a second membranous winged dinosaur was in front of my eyes,” Wang says. The 163 million-year-old fossil confirms that Yi was not an aberration or a one-off. Together, the two species represent an alternate evolutionary path for airborne dinosaurs.”

Not an aberration or a one-off, Dr. Wang…
two similar errors based on wishful thinking and cognitive bias.


References
Wang M, O’Connor JK.; Xu X and Zhou Z 2019. A new Jurassic scansoriopterygid and the loss of membranous wings in theropod dinosaurs. Nature 569: 256–259. doi:10.1038/s41586-019-1137-z
Xu X, Zheng X-T, Sullivan C, Wang X-L, Xing l, Wang Y, Zhang X-M, O’Connor JK, Zhang F-C and Pan Y-H 2015. A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings. Nature (advance online publication)
doi:10.1038/nature14423

reptileevolution.com/scansoriopterygidae2.htm

wiki/Yi_(dinosaur)
wiki/Ambopteryx

8 thoughts on “Like Yi qi, the new Ambopteryx does NOT have bat wings

  1. Your “tracing” – an attempt to interpret shades and colors in fig. 1A without any regard for preserved (if crushed) 3D shapes or any other part of basic taphonomy – not only invented something that looks like the distal end of a humerus on the distal end of the left styliform, but completely overlooked the left radius. Download the pdf, blow up fig. 1A to 1200%, and it’ll be plain as day that the left ulna lies on top of another long bone and that the distal expansion you put on the styliform is rock, not bone and not poorly preserved cartilage.

    • I will do so! Meanwhile, did you consider a longitudinal radial bone split? Did you see a styliform on the right side? Sometimes, actually often, buried bones reveal themselves by just the sort of bumps in the matrix you describe.

      • There aren’t any bones here that look split. There are no sharp or jagged edges or irregular shapes. Speaking of shapes, the right ulna looks a lot more like the left ulna (as identified by the authors) than like the left styliform.

        I don’t see the right styliform. But it is clear from comparing Figure 1, which shows the main slab, and Extended Data Figure 1a, which shows the counterslab, that most of the right hand is in an area where the slabs are badly broken so that some pieces of rock are altogether missing and the others haven’t been prepared. In short, there is no evidence that the right styliform was absent.

        Sometimes, actually often, buried bones reveal themselves by just the sort of bumps in the matrix you describe.

        When that happens, it’s obvious enough that the preparators attack it. I’ve seen the Vienna specimen of Confuciusornis before, during and after preparation. The distal head you give the styliform is nothing like that.

        Have you ever prepared such a specimen, or watched it being prepared?

      • This specimen and Yi qi made the news only because the authors claimed an extraordinary new bone produced an extraordinary new wing. Both wings of Yi qi were invalidated. The right wing of Ambopteryx demonstrates no new bone was present. The ‘styliform’ of the left wing was identical to the ulna in the right wing. NO sister taxa have even a vestige of such a novel bone. The authors made an extraordinary claim. I seek only ordinary evidence. Send your tracing of a high resolution image. I will go with the evidence, but you, or someone, has to demonstrate it so I can see it… and to your question… I’ve seen the ‘before’ and the ‘after’, not the ‘during’.

      • David, The closeup image is posted per your inquiry. The radius is crushed the long way giving the illusion of two bones. Notably there is no interosseum space, which never happens in birds.

  2. To be honest, I think the fossil’s more ambiguous than anything. The radius certainly does look as if it’s split, giving the impression of two bones. Then again, the radius seems to be longer and more curved, and then there’s the fact that it almost appears to articulate to the carpals!

    While I understand that (as you said to David) no sister taxa possess such a styliform element, the same could be said for the aye-aye (Daubentonia madagascariensis), which possesses a panda-like pseudothumb: https://onlinelibrary.wiley.com/doi/10.1002/ajpa.23936

    From what I could tell (maybe I missed something here), none of the aye-aye’s sister taxa possess such a pseudothumb. An intermediate form was definitely out there – we just haven’t found it yet. The same could be true for the scansoriopterygids.

    • Always interested in seeing how readers respond. Thank you.

      I showed the Yi qi break. I showed the reason for the break. No sister taxa have this very large bone. If this bone exists, then a large traditional bone in this story, the ulna, is essentially missing, at best a vestige disconnected from the elbow. This Yi qi myth has been inside our brain for five years. Let’s give time for the facts to percolate in and use Occam’s razor.

      re: Daubentonia… Analogs ≠ homologs. The pseudothumb the authors describe in Daubentonia does not protrude like a digit, but acts as a bulge in the palm to pull on digit 1. IMHO the ‘pseudothumb’ in the headline is an effort to headline-grab. The pisiform on the lateral wrist is much larger. Surprised they didn’t call that a pseudo-pinkie.

      • My point in the Daubentonia comparison is that no sister taxa (unless the LRT recovered one with a similar structure, in which case I missed it) possess such a “pseudo-pinkie”. To be honest, I actually prefer the term pseudo-pinkie.

        I’ll admit, even for me (who still thinks there is a chance that Yi might have had a styliform) it does seem unlikely – especially when even the paper’s figures suggest that a styliform is present, but that the ulna is (for whatever reason) absent!

        Re: Yi qi … I had to look it up, but it’s actually been six years. Six years without any irrefutable evidence of a styliform element is quite problematic.

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