It needs to be made clearer what is a new hypothesis in this paper and what ideas have been previously suggested in the literature. For example, you call Notocolossus and Dreadnoughtus “probable” and “putative” lognkosaurs, despite neither being considered lognkosaurs in previous research, and in fact both species have been shown not to be lognkosaurs in the past (González Riga et al., 2016). In addition, the text references Puertasaurinae and Futalognkosaurinae, both of which are nomina nuda. I would like it to be made clearer what “Puertasaurinae” and “Futalognkosaurinae” refer to, and I also think you should refer to them as “Puertasaurus clade” and “Futalognkosaurus clade” or something similar, rather than using a nomen nudum.
The phylogenetic dataset contains 399 characters, not 400 as stated in the text. Of these 399 characters, 24 are invariant and 94 more only differ in one taxon, so only 281 characters are parsimony-informative. Several characters are incorrectly ordered, seemingly due to using the character numbers of the matrix of González Riga et al. rather than the numbers in your modified matrix (González Riga et al., 2016). Furthermore, some new characters should be modified and ordered. Characters 138, 342, and 363 all describe continuous variables split into three discrete states, and as such should be ordered, though character 342 has the states incorrectly ordered, and should have states 1 and 2 switched.
The taxon sampling of your phylogenetic analysis is insufficient to properly test the relationships of the taxa you propose to be lognkosaurs. Pitekunsaurus has previously been found to be an aeolosaurin, and Dreadnoughtus has been suggested to have an affinity to aeolosaurs as well (Coria et al., 2013; Ullmann & Lacovara, 2016). In order to properly test their relationships, you should include other aeolosaurs. As Ruyangosaurus has been previously recovered as a non-lithostrotian somphospondyl, you should include a wider sample of basal somphospondyls, especially the other gigantic Asian taxa. Also, you should include Quetecsaurus and Bonitasaura, as both have been hypothesized to be the sister taxa of Lognkosauria before (González Riga & David, 2014; Gallina & Otero, 2015).
I have not taken the time to thoroughly review your data matrix, but some errors have already stuck out at me. Both Pitekunsaurus and Ruyangosaurus lack distal femora, but you code them as having proximally-placed fourth trochanters. Also, your extra state for character 212 of González Riga et al. (your character 244) is unnecessary, as “procoelous/distoplatyan” and “opisthoplatyan” refer to the same morphology.
Please present your phylogenetic results more clearly. You should state the length and number of the most parsimonious trees. Moreover, majority-rule consensus trees can be misleading. I would recommend presenting a strict consensus tree with unstable taxa pruned a posteriori instead.
Please familiarize yourselves with the phylogenetic definition of Lognkosauria. Lognkosauria is a node-based clade, defined as the most recent common ancestor of Futalognkosaurus and Mendozasaurus and all of its descendants (Calvo et al., 2007). According to your majority rule tree, Drusilasaura, Dreadnoughtus, Traukutitan, Pitekunsaurus, and Notocolossus are not lognkosaurs, but rather close relatives of the clade.
Calvo JO., Porfiri JD., González-Riga BJ., Kellner AW. 2007. A new Cretaceous terrestrial ecosystem from Gondwana with the description of a new sauropod dinosaur. Anais da Academia Brasileira de Ciências 79:529–541.
Coria RA., Filippi LS., Chiappe LM., García R., Arcucci AB. 2013. Overosaurus paradasorum gen. et sp. nov. , a new sauropod dinosaur (Titanosauria: Lithostrotia) from the Late Cretaceous of Neuquén, Patagonia, Argentina. Zootaxa 3683:357. DOI: 10.11646/zootaxa.3683.4.2.
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González Riga BJ., David LO. 2014. A New Titanosaur (Dinosauria, Sauropoda) from the Upper Cretaceous (Cerro Lisandro Formation) of Mendoza Province, Argentina. Ameghiniana 51:3–25. DOI: 10.5710/AMEGH.26.12.1013.1889.
González Riga BJ., Lamanna MC., Ortiz David LD., Calvo JO., Coria JP. 2016. A gigantic new dinosaur from Argentina and the evolution of the sauropod hind foot. Scientific Reports 6:19165. DOI: 10.1038/srep19165.
Ullmann PV., Lacovara KJ. 2016. Appendicular osteology of Dreadnoughtus schrani, a giant titanosaurian (Sauropoda, Titanosauria) from the Upper Cretaceous of Patagonia, Argentina. Journal of Vertebrate Paleontology 36:e1225303. DOI: 10.1080/02724634.2016.1225303.