Origin of avian flight paper needs a phylogenetic underpinning

Segre and Banet 2018
discuss the origin of avian flight like a parent trying to stop a fight among siblings. They’re off base, working without a phylogenetic underpinning. You’ll see what I mean.

From the Segre and Banet abstract
“Few topics in evolutionary biology have been as controversial as the debate over the origin of avian flight. Although significant progress has been made in understanding how dinosaurs acquired flight, the debate remains mired in historical perspectives that prevent progress. We would like to renew the call to set aside the arboreal / cursorial debate and to draw attention to the common ground shared by both sides. To this end, we propose the following starting points:

1. Paravian dinosaurs were bipedal, with decoupled but complementary hindlimb and forelimb locomotion.
2. They had feathers on their body, their wings and in many cases their legs, that were probably highly plastic and multi-functional.
3. Paravians inhabited complex, three-dimensional environments that required proficiency in a variety of behaviours to negotiate.
4. Once the incipient wing form existed, asymmetric and symmetric flapping and possibly static wing postures served a variety of aerodynamic purposes that enhanced fitness.

Taken together, these tenets conjure an exciting portrait of a dynamic organism adept at navigating through a complex environment with its versatile, incipient wings.”

Unfortunately,
Segre and Banet fail to mention the elongate coracoids that mark the genesis of flapping, and the origin of birds starting with the most primitive Solnhofen bird, the Thermopolis specimen attributed to Archaeopteryx. They would have known this if they had performed a phylogenetic analysis, which is the most important factor in determining in-groups and out-groups.

Missing the most basic point by skipping the phylogenetic analysis
The first bird is the last common ancestor of all birds. That’s it. That’s all. No matter what it looks like. Or what it has. And that taxon is… the Thermopolis specimen attributed to Archaeopteryx.

Pygostyles don’t matter.
Pygostyles appeared several times by convergence.

Wings don’t matter.
Unrelated Microraptor had wings.

The Thermopolis specimen
happens to have longer coracoids. So that’s a clue that the earliest birds were flapping, not gliding, from the beginning. This trait appearing at this node represents the origin, however tentative, of avian flight.

References
Segre PS and Banet AI 2018. The origin of avian flight: finding common ground. Biological Journal of the Linnean Society, bly116 (advance online publication) doi: https://doi.org/10.1093/biolinnean/bly116