“Kinematics of wings from Caudipteryx to modern birds”: Talori et al. 2018

A new paper without peer-review by Talori, Zhao and O’Connor 2018
seeks to “better quantify the parameters that drove the evolution of flight from non-volant winged dinosaurs to modern birds.”

Unfortunately
they employ Caudipteryx, an oviraptorosaur. They correctly state,
Currently it is nearly universally accepted that Aves belongs to the derived clade of theropod dinosaurs, the Maniraptora.” They incorrectly state, “The oviraptorosaur Caudipteryx is a member of this clade and the basal-most  maniraptoran with pennaceous feathers.” In the large reptile tree (LRT, 1269 taxa) oviraptorosaurs nest with therizinosaurus, and more distantly ornithomimosaurs. This clade is separated from bird ancestor troodontids by the Ornitholestes/Microraptor clade.

Figure 1. More taxa, updated tree, new clade names.

Figure 1. Caudipterys is in the peach-colored clade, far from the lineage of birds.

The Talori team
mathematically modeled Caudipteryx with three hypothetical wing sizes, but failed to provide evidence that the Caudipteryx wing was capable of flapping. In all flapping tetrapods the elongation of the coracoid  (or in bats of the clavicle) signals the onset of flapping… and Caudipteryx does not have an elongate coracoid. Rather, it remains a disc.

So, no matter the math, or the accuracy of the mechanical model,
the phylogeny is not valid and the assumption of flapping is inappropriate. It would have been better if they had chosen a troodontid and several Solnhofen birds to test.

Tossing those issues aside,
the Talori team did an excellent job of setting their mechanical model (which could be a troodontid) in a wind tunnel, extracting data from three different wing shapes and presenting their findings. Feathers would have been more flexible than their mold manufactured wings, but the effort is laudable.

References
Zhao J-S, Talori YS, O’Connor J-M 2018. Kinematics of wings from Caudipteryx to modern birds. [not peer-reviewed] bioRXiv
https://www.biorxiv.org/content/early/2018/08/16/393686

http://reptileevolution.com/reptile-tree.htm

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