It seems to me that I have never hidden the fact that I am not perfect. I know, I’m almost there. But alas, it can happen to make some mistakes.
Among the most popular articles and diagrams I’ve written, my post on how to portrait the wings of the members of Aviremigia have had a great success (first part : ktboundary-smnt2000.blogspot.i…; second part: ktboundary-smnt2000.blogspot.i…; third part: ktboundary-smnt2000.blogspot.i…). This is understandable: the wings of birds are among the most difficult animal parts to draw accurately, since they require an adequate understanding of their structure and variety, and this problem is also reflected in artistic depictions of extinct species, which may have feathered limbs more or less similar to those of their relatives today. This common problem pushed me to do a quick and simple guide on how to illustrate them. Despite the good will, the discoveries made in recent years and the anatomical oversights dictated by the lack of experience (J. Campbell- Smith, of all people, is the one who inspired me to revise everything, and for that I thank her very much) required a considerable restoration work that took me more a lot of time, but I hope that the results are satisfactory.
Models: Archaeopteryx and a generic maniraptoriform (based on Anchiornis)
Orange: lesser coverts
Dark orange: elongated lesser coverts
Light blue: median coverts
Blue: greater coverts
Dark blue: secondaries
Light brown: median primary coverts (lost in modern birds)
Brown: greater primary coverts
Green: scapulars (speculative)
Dark green: tertials (speculative)
Alula not present, but you can add it on the first digit.
Full post on my blog: ktboundary-smnt2000.blogspot.i…
Ps: sorry for the colours' quality. Bad scanner.
Evolution: Taking Wing with Weak Feathers. Xing Xu, 2012.
Plumage Color Patterns of an Extinct Dinosaur. Quanguo Li, Ke-Qin Gao, Jakob Vinther, Matthew D. Shawkey, Julia A. Clarke, Liliana D’Alba, Qingjin Meng, Derek E. G. Briggs, Richard O. Prum, 2010.
Structure and Function of hindlimb feathers in Archaeopteryx lithographica. Nicholas R. Longrich, 2006.
The asymmetry of the carpal joint and the evolution of wing folding in maniraptoran theropod dinosaurs. Sullivan, C., Hone, D., Xu, X., & Zhang, F. (2010).
Animals Real and Imagined: Fantasy of What Is and What Might Be, by Terryl Whitlatch (Editor), Gilbert Banducci (Editor)
The Prophet and the Liar, Chapter 03: Animal Anatomy. Link: theprophetandtheliar.tumblr.co…
External Anatomy of a Bird. Link: swartzentrover.com/cotor/Photo…
However it seems that in a lot of maniraptorans the wing feathers' lenght is similar to the humerus lenght. That is clear in some excellent fossils (Caudipteryx, Anchiornis, Jinfengopteryx, Similicaudipteryx, etc.) and seems to be the norm in many moden birds too, from ostriches to common pigeons (or, to put in another way, all the species with a 'generic' type of wing).
A fairer guess would've been Alula (or how I call them in non-avians: "Pseudoalula" - made-up term!), shown from the Microraptor fossil.
The multi-layering of Coverts is well-made!
Another thing to nitpick: According to skeletal reconstructions by Hartman, Headden, etc. the claw would rather point forward in a topview. That's obviously perspective-wise, but as you show it it looks more like the fingers are pointing backwards.
As explained below I went with the same definition as the authors when it comes to Tertials. Similar to Elijah's definition of Alula. So that might just be a talk at cross purposes.
About the Scapulars, they only make real sense (as you mentioned) in "paravians that had well defined flight feathers and reasonable degree of wing folding". We know that is not true for all of them. I think it highly likely that all of them had some kind of covering feathers on the shoulders. But I'm unsure to which degree we can refer to such (speculative) structures as Scapulars.
In my opinion a tutorial about "DinoWings" has always the problem of generalization and usage of maybe not appropriate terms.
"Scapulars and even more Tertials are veeeery speculative. A fairer guess would've been Alula (or how I call them in non-avians: "Pseudoalula" - made-up term!), shown from the Microraptor fossil."
Yes they are. But there is also the possibility that they aren't well preserved. Think about it: truth be told, the majority of feathered dinosaurs are known for some kind of feathers, but not all of them. Remiges are 'easly' preserved since they're attached to the bone, but the rest of the plumage is more 'delicate'. When tertials are missing, other types of plumage are missing as well. There is a huge gap between the remiges and the rest of the body and it seems pretty weird to me that there are no feathers at all to protect the remiges. Even ostriches and rheas have humeral and scapular feathers. To draw an aviremigian without any kind of humeral or scapular feather is like drawing a mammal without fur on the first part of the forelimb: it doesn't have any sense.
And to be fair, the alula is even more speculative. Microraptor, the most gliding dinosaur of them all, is the only genus to have it. Even Archaeopteryx, with its asymmetrical and wider feathers, similar to modern birds, didn't have it. I don't think it's wrong to portrait some maniraptorans with alulae, but I think it's a very rare feature.
"Another thing to nitpick: According to skeletal reconstructions by Hartman, Headden, etc. the claw would rather point forward in a topview. That's obviously perspective-wise, but as you show it it looks more like the fingers are pointing backwards."
So true. I wanted to focus so badly to the different types of feathers that I didn't care about where the claws pointed. But of course I'll keep that in mind!
Your support for Tertials is basically the same as mine for "Pseudalula".
It's just that I think of remiges when I hear Tertials, which are present in highly volant, mostly gliding bird-species. Modern Birds can do very well without having remigous Tertials [link], and still there is no distinct gap.
Here is an additional chart about the feather distribution on Avians. The gap you mentioned is covered by coverts/contour feathers.
And about me, I didn't either think that the "Pseudalula" would portray actual remiges or any flight support but just as you described the tertials.
Furthermore the term Scapular could also be confusing in context with non-avians as we really don't know if they had the same thing or just something analogous.
"I'm right now laughing about our duplicity.
Your support for Tertials is basically the same as mine for "Pseudalula"."
Yeah, great minds, same thoughts .
Passeriforms are actually the only group withouth tertials, all other birds have them. In this type of birds, the remiges close to the body have the same function as the tertials (to protect the other remiges) in other birds, that's why they lost them. For this reason I believe that they might be present in ancient taxa, even if not developed to such a degree.
The gap I mentioned is in fact covered by humeral (which are a unique kind of coverts) and scapular feathers (which are body feathers), as you said.
"Furthermore the term Scapular could also be confusing in context with non-avians as we really don't know if they had the same thing or just something analogous."
I think it's confusing for non aviremigians, but otherwise it seems plausible to suppose their presence. Even if there was something analogous, we must draw such a thing, don't you agree?
I know what you are questioning. The "some maniraptorans might not have had feathers on their second finger so they could hunt better" argument is what I'm exasperated by. This has been brutally and thoroughly debunked. We've known that feathers attach to the second finger for over 10 years. The first study stating outright that they would not get in the way of predation came out 8 years ago. The first study detailing how they may have been used in predation came out 3 years ago.
On the other matter. Again, no study has EVER said that a theropod can pronate their hands, but it would appear from your comments to SMNT that you may have misinterpreted what the word means, so that’s fine.
"So, this is the way many theropod hands must be reconstructed???"
Well, not all of them. Just the Aviremigians: en.wikipedia.org/wiki/Chuniaoa…