Czerkas and Feduccia disconnect birds and dinos

Figure 1. Reconstruction of Scansoriopteryx with possible feather extent by Stephen Czerkas. Good thing that second branch or telephone wire is available for balance!

Figure 1. Reconstruction of Scansoriopteryx with possible feather extent by Stephen Czerkas. Good thing that second branch or telephone wire is available for balance!

A new paper by Czerkas and Feduccia
attempts to unlink birds with dinosaurs and to link birds with some unspecified archosaur by their reexamination of Scansoriopteryx, a tiny Chinese fossil of the Jurassic. Much has already been said about this paper — all negative.

Czerkas and Feduccia report the “absence of fundamental dinosaurian characteristics,” but do not do so with phylogenetic analysis, which would have nested their study subject somewhere else that they could support, but can’t. They seem stuck in a trees-down vs. ground up battle when plenty of ground-dwelling dinosaurs seem fully capable of climbing a tree by grappling or simply by running up a vertical trunk bipedally, as some modern birds do (any Dial reference below). Their illustration (Fig. 1) seems to say that whether bird or dinosaur or non-dinosaur, Scansoriopteryx was not capable of standing balanced on its (apparently splayed?) hind limbs, despite the fact that it’s forelimbs appear poorly designed for walking. They’ve been accused of LarryMartinizing and it seems they have indeed been doing so. For those interested, Larry Martin preferred to discuss individual characters rather than suites of characters of a sort used in phylogenetic analysis.

I can’t buy into their particular heresy.
There’s no support for it. We need to see details and analyses. And they need to present their best alternative candidate among the non-dinosaurian archosaurs out there as a sister to Scansoriopteryx. 

The irony here
is that the same sort and style of argumentation is being used to support a pterosaur/archosaur connection by the same set of paleontologists who support the dino/bird connection. By that I mean, they present no archosaurian candidates that more closely match pterosaurs than our own favorites: the lepidosaur, tritosaur, fenestrasaurs.

So, if you’re a finger pointing paleontologist, be careful. Don’t fall into  that same trap.

References
Czerkas SA and Feduccia A 2014. Jurassic archosaur is a non-dinosaurian bird, Journal of OrnithologyDOI: 10.1007/s10336-014-1098-9
Dial KP, Jackson BE and Segre P 2008.  A fundamental avian wing-stroke provides a new perspective on the evolution of flight. Nature (online 23 Jan 08)
Padian K and Dial KP 2005. Could the “Four Winged” Dinosaurs Fly?  Nature: 438:E3-5.
Dial KP, Randall R and Dial TR 2006. What use is half a wing in the evolution of flapping flight? BioScience 56: 437-445.
Tobalske BW and Dial KP 2007. Aerodynamics of wing-assisted incline running. J. Exp. Biol. 210:1742-1751.
Bundle MW and Dial KP  2003. Mechanics of wing-assisted incline running.  J. Exp. Biol., 206:4553-4564.
Dial KP 2003.  Evolution of avian locomotion: Correlates of body size, reproductive biology, flight style, development and the origin of flapping flight. Auk 120:941-952.
Dial KP 2003. Wing-assisted incline running and the evolution of flight.  Science 299:402-404.
Read more at: http://phys.org/news/2014-07-declassify-dinosaurs-great-great-grandparents-birds.html#jCp

 

How Birds Got Their Wings

A recent article, “How Birds Got Their Wings,” also here, here and here describe work by Dececchi and Larsson (2013) that noted scaling of forelimb vs hind limb took a big turn with Archaeopteryx and kin (Fig. 1). They note, as forelimbs lengthened, they became long enough to serve as an airfoil, allowing for the evolution of powered flight. Shorter legs would have aided in reducing drag during flight — the reason modern birds tuck their legs as they fly — and also in perching and moving about on small branches in trees.

That’s all well and good, but its not the key. It’s one step following the key.
The key is flapping. That’s a behavior that definitely leads to flight. Having long forelimbs vs. hind limbs is also found in primates, chalicotheres and sloths. They don’t fly. Even the “flying lemur” Cynocephalus had long arms. All it can do is glide because it doesn’t flap.

Figure 2. Cosesaurus running and flapping - slow.

Figure 1. Click to animate. Cosesaurus running and flapping – slow.

The key to flapping is a locked down coracoid.
As we learned earlier with Cosesaurus (Fig. 1), a locked down coracoid is one thing pterosaurs and birds share. Cosesaurus had fibers trailing its forelimbs (Ellenberger 1993, Peters 2011) but its forelimbs were too short to fly. Nevertheless, it could flap because it had a locked down coracoid. And that was a secondary sexual trait (behavior) that led to more of the same in three distinct directions in Sharovipteryx, Longisquama and basal pterosaurs.

Taxa in the lineage of birds.

Figure 2. Taxa in the lineage of birds. From top to bottom: Tawa, Juravenator, Sinocalliopteryx, Archaeopteryx, Cathayornis, Sinornithes plus enlarged skulls. Note the coracoid becomes taller and fixed in Archaeopteryx.

Other dinosaurs
with long forelimbs and a tall, narrow, locked down coracoid include oviraptorids, dromaeosaurids, alvarezaurs and birds all taxa that phylogenetically follow Archaeopteryx.

And bats?
They have a locked down tall clavicle that serves the same function. We don’t know when they started flapping because the closest known fossils of prebats are all skull material only.

Reference
Dececchi TA and,  Larsson HCE 2013. Body and Limb Size Dissociation at the Origin of Birds: Uncoupling Allometric Constraints Across a Macroevolutionary Transition. Evolution 67(9):2741 DOI:10.1111/evo.12150

A protobird lesson from Spitfire exhaust ports

Just a minor rant…

Figure 1. Sinornithosaurus running in pursuit of Microraptor. Click to see video. Neither of this animated creatures is using its forelimbs to generate thrust. What are they waiting for??

Figure 1. Click to see video. Sinornithosaurus running in pursuit of Microraptor. Neither of these animated creatures is using its forelimbs to generate thrust. What are they waiting for??

I notice in animated protobirds and dromaeosaurids that they keep the arms nearly motionless while running (here), even though feathered (Fig. 1). Basically only the legs are providing thrust. The wings are only providing drag via decoration.

Figure 2. Click to see video. Microraptor gliding without so much as even a little flapping. What is it waiting for??

Figure 2. Click to see video. Microraptor gliding without so much as even a little flapping. What is it waiting for??

Figure 2. Click to see video. Microraptor gliding without so much as even a little flapping. What is it waiting for??

Same goes for animated climbing and gliding, like this animation of Microraptor. Very little to no flapping is shown in some sort of attempt at showing a primitive form of flying = weak gliding. What would happen if these hot little dinosaurs did a little flapping? Or a lot of frantic flapping whether on the ground or in the air? So what if they don’t have big sterna!

Start with a behavior, the skeleton will follow.
At this point we all are thinking about WAIR (wing-assisted incline running) discovered by Kenneth Dial (2003). All you have to do is take away the incline. Keep those birdy’s flapping!

And you don’t even need a wing to start with
Earlier we noted that, like birds, protopterosaurs (like Cosesaurus, Fig. 3) also developed a stem-like, locked-down coracoid which enabled flapping and discouraged traditional quadrupedal locomotion. And Cosesaurus was a long way off from developing wings and flying. However, starting with this odd secondary sexual behavior bigger, thrust and lift producing forelimbs came quickly in pterosaurs and Longisquama once flapping commenced in earnest.

Figure 1. Cosesaurus flapping - fast. There should be a difference in the two speeds. If not, apologies. Also, there should be some bounce in the tail and neck, but that would involve more effort and physics.

Figure 3. Click to enlarge and animate. Cosesaurus flapping – generating feeble thrust with its frilled forelimbs held off the ground. Even a little extra thrust, as it turns out, can prove to be the winning edge in survival.

So why don’t dino animators add a little thrust 
to their running protobirds by adding a little frantic flapping of the forelimbs? After all, that’s how many (not all!) flying birds run (think chickens, sparrows and robins). And flapping wings still develop lift. So there’s no trade-off.

Well, modern bipedal lizards don’t flap. But then they all have a traditional coracoid and no arm frills. Many modern running birds, like the roadrunner and ostrich, don’t flap while they run. But chickens, ducks and songbirds do. So, the analog only goes so far.

What can the WWII Supermarine Spitfire tell us about thrust?

Figure 2. Hot gases firing out of exhaust ports on a Supermarine Spitfire add 70 hp at 300 mph

Figure 2. Hot gases firing out of exhaust ports on a Supermarine Spitfire added 70 hp at 300 mph. This concept ultimately became the modern jet engine producing all the thrust.

From Wikipedia: “In1938 the Spitfire was flown for the first time with ejector exhausts, developed for the Merlin by Rolls-Royce. With these it was found that the exhaust [gase]s [produced] 70 pounds of thrust, equivalent to about 70 hp at 300 mph.”

The takeaway
Even a little added thrust = added horsepower and added speed. And flapping had to start somewhere. Why not when feathers and a locked-down coracoid showed up? Start with a little, then move up to a lot. That’s the way evolution works.

References
Dial KP 2003. Wing-Assisted Incline Running and the Evolution of Flight (abstract). Science 299 (5605): 402–404. Bibcode:2003Sci…299..402D.doi:10.1126/science.1078237. PMID 12532020.

Wiki/origin of avian flight

Archaeoraptor – Chimaeras and Fakes – Part 3

It has been called a scandal, a hoax, an embarrassment and a fraud. If you’re already familiar with the story of Archaeoraptor, I’m not adding anything new here. Everyone already knows Archaeoraptor was a chimaera, another “complete” fossil put together from bits and pieces of several specimens. The references below, especially Wiki, tell the story.

Figure 1. At left Archaeoraptor as it appeared. At right Archaeraptor as it was assembled into a chimaera, from Rowe et al. 2001.

Figure 1. At left Archaeoraptor as it appeared. At right Archaeraptor as it was assembled into a chimaera, from Rowe et al. 2001.

Let’s not forget that the individual pieces still hold scientific value when separated.

This music video from the Offspring should be the final word.

References
Knevitt O. 2011. The 5 Greatest Palaeontology Hoaxes of all Time #3. Archaeoraptoronline here.
Rowe T, Ketcham RA, Denison C, Colbert M, Xu X, and Currie PJ 2001.
 Forensic palaeontology: The Archaeoraptor forgery. Nature 410 (6828) (March 29): 539-540. doi:10.1038/35069145. abstract here.
Online BBC video documentary here.

A paper written on fossil fakes is online here.

Wiki/Archaeoraptor

What?? No feathers on velociraptors?

Figure 1. Inside cover illustration spread for "Raptors, the Nastiest Dinosaurs" by Don Lessem, illustrated by David Peters. Don asked for a "no feathers dinosaur" so that's what he got. Don't blame the artist. I tried to persuade. Utahraptor is the big dromaeosaur here.

Figure 1. Inside cover illustration spread for “Raptors, the Nastiest Dinosaurs” by Don Lessem (1996), illustrated by yours truly, David Peters. Don asked for a “no feathers dinosaur” so that’s what he got. Don’t blame the artist. I tried to dissuade. Utahraptor is the big dromaeosaur here.

This post was inspired
by a blog and Flickerstream I ran across here and here that bemoaned the fact that my 1996 dromaeosaurids / velociraptors (Fig. 1) in “Raptors – The Nastiest Dinosaurs” did not have feathers, but did have propatagia.

Guys, I tried to add feathers, as I had done several years earlier (1989) to my own velociraptors in Gallery of Dinosaurs (Fig. 2). However, author Don Lessem insisted that no feathers appear in his book. I tried to dissuade, but was vetoed. After all, he is the author. And that was then. I’m sure Dino Don has come around to new thinking since then.

See how difficult it is to promote a new idea supported by data? Even an expert like Don Lessem balked back in 1995-6.

Figure 2. Feathered Deinonychus from A Gallery of Dinosaurs by David Peters.

Figure 2. Feathered Deinonychus from A Gallery of Dinosaurs by yours truly, David Peters. (1989). Click to enlarge.

So, there is a backstory,
as there is with other controversial aspects of my work. At present the backstory and trashed ideas are not as important as the current work. Science marches on and new data keeps coming in. So let’s stay with the current wave. If you see any other problems with my  tracings or identifications, please let me know of those issues.

References
These are kids books, not academic journals!
“A Gallery of Dinosaurs” is online here.

Jason Brougham Deinonychus skeleton model

This is excellent!

Figure 1. Deinonychus skeleton model by Jason Brougham. Click to learn more.

Figure 1. Deinonychus skeleton model by Jason Brougham. Click to learn more.

And if you haven’t become acquainted with artist/scientist, Jason Brougham, I hope you do so now. Incredible and accurate detail, dynamic pose and very birdy.

Lateral view of Deinonychus by Jason Brougham.

Figure 2. Lateral view of Deinonychus by Jason Brougham.

It’s not very often that a skeleton seems this alive.

See more at jasonbrougham.com

Aurornis xui – A New Bird-like Dinosaur with Feathers

“A birdlike fossil that dates to roughly 155 million years ago is ruffling the feathers of some paleontologists. At issue is whether the fossil is a dinosaur, an early bird or something in between,” Rachel Ehrenberg of Science News wrote. “This new animal is the most primitive bird in the world,” says paleontologist Pascal Godefroit of the Royal Belgian Institute of Natural Sciences.

And further down, Ehrenberg writes, “Not everyone agrees with Godefroit’s interpretation. ‘This is very birdlike, but it is not yet a bird,’ says paleontologist Luis Chiappe of the Natural History Museum of Los Angeles County.”

The name of the new dinosaur with feathers is Aurornis xui. Twice as tall as Archaeopteryx (Fig. 1) and three times as long, Aurornis preceded Archaeopteryx by 10 million years and lived in China.  Lacking large feathers, Aurornis did not fly, but would have been a speedy runner. Aurornis phylogenetically precedes Archaeopteryx and all other birds. So is it a bird? Or pre-bird?

Who is right? 
Here is the traced specimen. The fossil appears here online. The coracoids are hard to see as they overlap one another in situ, but they appear to be strut-like. If so, Aurornis flapped, not that that matters…but if Archaeopteryx was a poor flyer, than Aurornis didn’t have a chance.

Aurornis xui in situ and reconstructed alongside Archaeopteryx to the same scale. Click to enlarge.

Figure 1. Aurornis xui in situ and reconstructed alongside Archaeopteryx to the same scale. Click to enlarge. Aurornis is a larger animal, but with a skull and pelvis not much larger than in Archaeopteryx.

Bird Ancestor? 
Earlier we looked at taxa that phylogenetically preceded Archaeopteryx (all larger) and several taxa that phylogenetically succeeded Archaeopteryx (all smaller, but later forms grew larger). Aurornis was too large to fly. It did not have flight feathers or tail tip feathers. Archaeopteryx was able to fly feebly with large flight feathers and tail tip feathers on a smaller body.

Everyone wants to find the first, the biggest, the best, etc. 
It comes down to how paleontologists and ornithologists define what a bird is. According to Luis Chiappe of the Natural History Museum of Los Angeles County quoted in LiveScience“Traditionally, we have defined birds as things like Archaeopteryx and closer to things like modern birds. If you stick to the definition, this thing is not the earliest known bird.” Even so, it is a very interesting animal that “still helps us understand better the origin of birds,” Chiappe said.

Indeed
Aurornis is a wonderful new taxon that gives greater insight into the origin of birds, but it is not one by definition.

References
Godefroit P, Cau A, Hu D-Y, Escuillié  F, Wu W-H and Dyke G 2013. A Jurassic avialan dinosaur from China resolves the early phylogenetic history of birds. Nature .doi:10.1038/nature12168.

wiki/Aurornis

Eosinopteryx – part 3 – to scale

Sometimes it just helps
to see taxa to scale with possible sisters (Eosinopteryx in this case, Fig. 1). Smaller than Anchiornis, Eosinopteryx also had a shorter snout, deeper mandible, more robust postorbital, longer torso, shorter tail, larger chevrons, more robust clavicle, coracoid and scapula, shorter forelimb, smaller deltopectoral crest and shorter pubis.

Eosinopteryx and kin to two scales.

Figure 1. Eosinopteryx and kin to two scales.

Huaxiangnathus shared with Eosinopteryx a short coracoid, but little else is a closer match than the similarly built Anchiornis. Godefroit et al. (2013) reported, “The straight and closely aligned ulna-radius of Eosinopteryx also means that pronation/supination of the manus with respect to the upper arm would have been limited; combined with the absence of a bony sternum and weakly developed proximal humerus, these attributes suggest that Eosinopteryx had little or no ability to oscillate the arms to produce a wing beat.”

Funny that they didn’t even mention the short coracoid.
The locked down elongate coracoid is a hallmark of flapping tetrapods (pterosaurs and birds) and an elongate clavicle does the same thing in bats.

According to the Sinkkonen illustration (Fig. 1), the radius and ulna are likewise essentially straight in Anchiornis, which is the plesiomorphic condition, as shown by Huaxiagnathus and other theropods. The ulna is barely bowed in Archaeopteryx and more greatly bowed in subsequent flapping taxa, including oviraptorids (by convergence?). Xiaotingia (Fig. 2), the outgroup to Anchiornis + Eosinopteryx, also has a short rostrum, but also a greatly bowed anterbrachium and a locked-down coracoid. I suspect a change in tree topology may be warranted or else we’ll learn something here about reversals.

I have asked for the matrix.

Figure 2. Xiaotingia the outgroup to Achiornis + Eosinopteryx + other Troodontidae. Red arrow points to bowed antebrachium. DGS enabled identification of the coracoids, which are elongated here.

Figure 2. Xiaotingia the outgroup to Anchiornis + Eosinopteryx + other Troodontidae. Red arrow points to bowed antebrachium. DGS enabled identification of the coracoids, which are elongated here. This is a flapping theropod. Inset shows previous tracing that did not identify two coracoids.

The bowed antebrachium
produces a parallelogram in living birds that serves to automatically extend and fold the manus bearing the outer flight feathers with flexion/extension of the elbow. Prior to this, muscle power would have to extend and bend the wrist, independent of the flexion/extension of the elbow.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Godefroit P, Demuynck H, Dyke G, Hu D, Escuillié FO and Claeys P. 2013. Reduced plumage and flight ability of a new Jurassic paravian theropod from China. Nature Communications 4: 1394. doi:10.1038/ncomms2389

wiki/Eosinopteryx

Eosinopteryx – part 2 – Better Resolution = Better Reconstruction

Yesterday we looked at Eosinopteryx (Godefroit et al. 2013, Middle-Late Jurassic, Tiaojishan Formation) and discussed a possible new nesting site (Fig. 1) based on a lack of included short-coracoid taxa preceding Archaeopteryx to compare it with. By comparison, Cosesaurus has a “flapping”-type coracoid and it has much less wing tissue trailing its front limbs. So the long, locked-down coracoid in bird predecessors was among the last traits to evolve, post-dating the appearance of elongated forelimb feathers.

Supplementary information

Figure 1. Supplementary information from Godefroit et al. (2013) showing their nesting of Eosinopteryx with Anchiornis, but the tree lacks several short-coracoid taxa that might provide more parsimonious nesting sites.

Addendum: The analysis of Godefroit et al. (2013) was based on and provided only a segment of an earlier analysis that DID include these more primitive taxa. Thus my doubt is reduced considerably as all pertinent taxa were included. The skull on DGS

Not sure if a skull reconstruction was provided by Godefroit et al. (2013) or not. (not) I’d still like to see the paper. (I have the paper now. ) Even so, in order to create yesterday’s reconstruction I applied DGS (digital graphic segregation) to the skull (Fig. 2). I don’t know birds as well as dinosaurs and did not attempt a palate reconstruction. If I made any mistakes, please send me an email. (Figure 2 is an update based on higher resolution images of an earlier posted figure.)

Figure 2. The skull of Eosinopteryx in situ (above), traced using DGS (middle), and as presented by G et al. 2013). The red bone is the quadrate sticking through the mandibular fenestra, which was purportedly missing.

Figure 2. The skull of Eosinopteryx in situ (above), traced using DGS (middle), and as presented by Godefroit et al. 2013). The red bone is the quadrate sticking through the mandibular fenestra, which was purportedly missing. See Figure 3 for reconstruction and bone identification. While my tracing appears to be chaotic, every bone was traced on a separate and segregated layer.

Above
The skull of Eosinopteryx traced using Photoshop, a process known as DGS or Digital Graphic Segregation. For followers of this blog, these updated images reflect the importance of high resolution data in using DGS. Much like the Hale telescope, greater resolution enables the identification of finer lines and bones. This demonstrates that its not the mechanics of the technique so much, as the intimate knowledge long months of study provides when employed, and higher resolution really helps. (Higher resolution image did provide improved data.)

Figure 3. The skull of Eosinopteryx after tracing in higher resolution (1200 dpi). Here more bones and teeth were correctly traced and identified. A mandibular fenestra is present (contra Godefroit et al. 2013). It just had a quadrate stuck through it. Frontals overlap due to convexity. Even with these improvements, any errors should be brought to my attention for repair.

Figure 3. The skull of Eosinopteryx after tracing in higher resolution (1200 dpi). Here more bones and teeth were correctly traced and identified. A mandibular fenestra is present (contra Godefroit et al. 2013). It just had a quadrate stuck through it. Frontals overlap due to convexity. Even with these improvements, any errors should be brought to my attention for repair.

The premaxilla includes at least three elongated teeth (here seen from the inside). The saddle-shaped nasal was broken into at least four pieces during crushing. The maxilla is decayed beyond the normal fenestration. Here (Fig. 3) I reconstruct it conventionally. There is no elongated posterior lacrimal process and vestigial anterior process as Godefroit et al. (2013) reported. Rather the lacrimal is similar to that of other theropods. They did not provide a reconstruction. An earlier reconstruction of mine misplaced the quadrate articulation, which is repaired here. It also did not recognize the posterior mandible, which in situ is separated from the articular area. But here (Fig. 3) this has been repaired, thanks to theropod expert, M. Mortimer, for pointing this out. It was also overlooked by Godefroit et al. (2013, Fig. 2).

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Godefroit P, Demuynck H, Dyke G, Hu D, Escuillié FO and Claeys P. 2013. Reduced plumage and flight ability of a new Jurassic paravian theropod from China. Nature Communications 4: 1394. doi:10.1038/ncomms2389
Paul GS 2010. The Princeton Field Guide to Dinosaurs. Princeton University Press 320 pp.

wiki/Eosinopteryx

Eosinopteryx – part 1 – Feathers, but no flapping

Eosinopteryx brevipenna (Godefroit et al. 2013, Middle-Late Jurassic, Tiaojishan Formation) is represented by a new complete skeleton. It was a feathered theropod dinosaur about 30 cm long. The forelimb feathers were quite long (Fig. 1), but the tail feathers were not.

Paravian? or Preavian?
We’ve been looking for a feathered theropod without elongated coracoids to precede Archaeopteryx. We also need this taxon to be not pre-oviraptorid or pre-alvarezsaurid. The authors argue, with a very extensive phylogenetic analysis, that this is a troodontid resembling Anchiornis, with less extensive feathers on the hind limbs and tail. Anchiornis greatly resembled Archaeopteryx and is, therefore, closely related. Of that, there is no doubt.

Why There is Doubt
I have not created a competing analysis. Checking out Greg Paul’s figure of Anchiornis (Paul 2010), I note his Anchiornis has the short torso and elongated coracoid also seen in Archaeopteryx, troodontids and deinonychosaurs.

Figure 1. Click to enlarge. Eosinopteryx reconstructed in lateral view. Soft tissue impressions preserved on the fossil are represented here in gray. Note the small size of the coracoid (yellow) and its curved lower rim, which indicates this specimen was a pre-flapping dinosaur. Pedal digit 2 was not modified as a "killing" claw. Elements figured with DGS.

Figure 1. Click to enlarge. Eosinopteryx reconstructed in lateral view. Soft tissue impressions preserved on the fossil are represented here in gray. Note the small size of the coracoid (yellow) and its curved lower rim, which indicates this specimen was a pre-flapping dinosaur. Pedal digit 2 was not modified as a “killing” claw. Elements figured with DGS.

What sets Eosinopteryx apart from these?
A short coracoid with a broad curved ventral rim - Therefore Eosinopteryx did not flap and was not descended from flappers. We haven’t seen a terrestrial descendant of Archaeopteryx yet without elongated coracoids. For more on this, compare Huaxiagnathus (with its short coracoid) to Velociraptor, (with its long, tall coracoid). Otherwise these two greatly resemble one another, with the former lacking sternal plates, a retroverted pubis and caudal rods. These traits are also lacking in Eosinopteryx.

A relatively smaller skull – Much smaller than in Anchiornis.

A relatively longer torso – Much longer than in Anchiornis.

A relatively shorter pubis – Much shorter than in Anchiornis.

All these traits are primitive for theropods.

Unfortunately, 
Huaxiagnathus
 was not included in the analysis of Godefroit et al. (2013). Neither were oviraptorids or alvarezsaurids. Eosinopteryx
needs to be compared to these missing basal taxa along with the other taxa they previously tested. Once that’s done, let’s see if the topology of the tree doesn’t shift Eosinopteryx down below (more primitive than) Archaeopteryx. 

Addendum: The analysis of Godefroit et al. (2013) was based on and provided only a segment of an earlier analysis that DID include these more primitive taxa. Thus my doubt is reduced somewhat as all pertinent taxa were included.  Even so, I wonder why these two “sisters” don’t look more alike.

If anyone has details on why Godefroit et al. 2013 said the “bone structure would have limited its ability to flap its wings,” I’d like to see it.

Interesting that this birdy topic just came up a few days ago with Mahakala. Reminds me to be careful what I wish for.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Godefroit P, Demuynck H, Dyke G, Hu D, Escuillié FO and Claeys P. 2013. Reduced plumage and flight ability of a new Jurassic paravian theropod from China. Nature Communications 4: 1394. doi:10.1038/ncomms2389
Paul GS 2010. The Princeton Field Guide to Dinosaurs. Princeton University Press 320 pp.

wiki/Eosinopteryx