Is it just me, or is the section "We also highlight anatomical differences between the humerus of
M.
namunhuaiquii and that of the enigmatic Patagonian theropod
Gualicho
shinyae Apesteguía et al., 2016, that show that these taxa are not
closely related" an example of Makovicky and Dyke's (2001) famous Naive Falsification fallacy? As a reminder, it's point is that when e.g. Feduccia or Martin would claim a structure differs between dinosaurs and birds, those authors believed it meant the two groups couldn't be closely related. The classic case was
Velociraptor's furcula, which "has a round cross-section, while that of the primitive Mesozoic birds —
Archaeopteryx,
Confuciusornis and the enantiornithines — is dissimilar, being grooved postero-dorsally along almost its entire length" (Feduccia and Martin, 1998). So yeah, we all agree
Gualicho has a dissimilar humerus from
Megaraptor,
Australovenator and
Fukuiraptor, but that's meaningless without suggesting a greater similarity to another taxon which you feel is phylogenetic in nature. But Calvo et al. explicitly say "like
Gual. shinyae, alvarezsaurids and tyrannosaurids have short forelimbs, which strongly suggests that these similarities represent convergences rather than shared apomorphies" and "the humeral similarities between
Gual. shinyae and ornithomimosaurs are probably best interpreted as functional convergences rather than apomorphic traits." So if all these characters are convergent, it tells us nothing about the affinities of
Gualicho. Considering humeral characters alone,
Gualicho might as well be a megaraptoran that converged with ornithomimosaurs instead of e.g. a ceratosaur that converged with ornithomimosaurs. To make any headway in the direction Calvo et al. want to, you would have to show the characters joining
Gualicho to megaraptorans in analyses where it falls out as one are flawed, AND show a better result for placing it in another clade.
References-
Feduccia and Martin, 1998. Theropod-bird link reconsidered. Nature.
391, 754.
Makovicky and Dyke, 2001. Naive falsification and the origin of birds: A commentary. In Gauthier and Gall (eds.). New
Perspectives on the Origin and Evolution of Birds: Proceedings of the
International Symposium in Honor of John H. Ostrom. Yale University. 501-509.