Rebuttal of Martin-Silverstone et al. 2017, ‘Reassessment of Dawndraco kanzai Kellner 2010 and reassignment of the type specimen to Pteranodon sternbergi Harksen, 1966’

Abstract

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Nurhachius luei, a new istiodactylid pterosaur (Pterosauria, Pterodactyloidea) from the Early Cretaceous Jiufotang Formation of Chaoyang City, Liaoning Province (China) and comments on the Istiodactylidae

“…Both specimens of N. ignaciobritoi come from the upper part of the Jiufotang Formation (see Wu et al, 2018), while the holotype of N. luei comes from the lowermost part of the Jiufotang Formation. This stratigraphic distribution might be suggestive of an anagenetic link between the two species, similar to the case of Pteranodon longiceps (from the upper Smoky Hill Chalk) and Pteranodon sternbergi (from the lower Smoky Hill Chalk) according to Bennett (1994), but see taxonomic controversies (Kellner, 2010, 2017; Martin-Silverstone et al, 2017; Acorn et al, 2017). The same has been speculated as a possible explanation for the occurrence of multiple species of Anhanguera (Pinheiro & Rodrigues, 2017), Thalassodromeus and Tupuxuara (Pêgas, Costa & Kellner, 2018) in the Romualdo Formation.…”

Response to Kellner (2017) 'Rebuttal of Martin-Silverstone, E., J.R.N. Glasier, J.H. Acorn, S. Mohr, and P.J. Currie, 2017'

“…9). Kellner (2017) does not mention these data in his rebuttal. Instead, he focuses on comparisons between only two specimens: UALVP 24238 and FHSM VP 339 (the holotype of Pteranodon sternbergi).…”

“…This difference, between what might be termed statistical and non-statistical approaches, is, in our opinion, the reason behind what Kellner (2017) calls, "the importance of this debate for pterosaur research in general." However, from a statistical perspective, the quantitative techniques involved here are very simple, so it is important to realize that this debate is not about the difference between good statistics and bad, it is about the difference between some statistics and none.…”

“…Instead, he focuses on comparisons between only two specimens: UALVP 24238 and FHSM VP 339 (the holotype of Pteranodon sternbergi). Kellner maintains that because both are mature males, the differences between them (the shapes of the rostra and craResponse to Kellner (2017) nial crests) are taxonomic, not ontogenetic or the product of intraspecific variation. We appreciate how tempting it is to look at Kellner's (2017) Figure 1, and conclude that these two specimens represent obviously different taxa.…”

“…Kellner maintains that because both are mature males, the differences between them (the shapes of the rostra and craResponse to Kellner (2017) nial crests) are taxonomic, not ontogenetic or the product of intraspecific variation. We appreciate how tempting it is to look at Kellner's (2017) Figure 1, and conclude that these two specimens represent obviously different taxa. Coincidentally, however, in a recent blog post, that appeared before our paper was published, another pterosaur specialist, Mark Witton (2016) presents a figure almost identical to Kellner's, superimposing outline drawings of the same two skulls plus Kellner's Geosternbergia maiseysi holotype.…”