New hadrosaurids from Upper Cretaceous of Sonora, Mexico

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

A new paper:

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Rubén Duarte-Bigurra, Alba Vicente, Cirene Gutiérrez-Blando, Claudia I. Serrano-Brañas, Jonathan R. Wagner & Albert Prieto-Márquez (2026)
New hadrosaurid dinosaurs from the middle Campanian (Upper Cretaceous) of Sonora (Mexico) extend the South American kritosaurin lineage to southern Laramidia
Journal of Systematic Palaeontology 24(1): 2656218
doi: https://doi.org/10.1080/14772019.2026.2656218
https://www.tandfonline.com/doi/full/10.1080/14772019.2026.2656218


The non-marine deposits of the Campanian–early Maastrichtian Cabullona Group (north-eastern Sonora, north-western Mexico) have yielded abundant fossils of continental vertebrates, including dinosaurs. However, this dinosaur fauna has yet to be studied in detail. We describe three partial hadrosaurid specimens from two localities (Arroyo del Alamito and Puerto Viejo) in the Fronteras Municipality of Sonora. All three localities correspond to the middle Campanian strata of the lower part of the Fronteras section of the Cabullona Group. The specimens are represented by partial axial and appendicular elements. The most complete individual (2997 PM 1) was collected at Puerto Viejo and consists of several axial elements, a partially complete pelvic girdle and hindlimb fragments. The parsimony phylogenetic analysis positioned the three Fronteras specimens deeply nested within the speciose saurolophine tribe Kritosaurini, as members of a subclade so far restricted to Patagonia, Argentina (here informally referred to as ‘secernosaurs’). Thus, the Fronteras hadrosaurids represent the first record of secernosaurs outside South America, greatly extending their biogeographical distribution to Late Cretaceous southern Laramidia. Inference of ancestral areas for the clades recovered in the phylogeny supports the hypothesis that hadrosauroids dispersed to South America via Southern Laramidia.

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[Mickey Mortimer]

The authors write- "The name “Austrokritosauria” (Alarcon-Munoz et al., 2023) has been proposed for a ‘secernosaur’ clade, but this name is not available under the International Code of Zoological Nomenclature (International Commission on Zoological Nomenclature, 1999 [Hereafter the “ICZN Code”]). “Austrokritosauria” would necessarily be a family-group name (ICZN Code, 1999, 35.1), but it was not published properly (ICZN Code, 1999, 11.7, 16.2) and is not properly formed from the stem of a genus name (ICZN Code, 1999, 13.2, 25, 29), and is therefore unavailable under the ICZN Code (1999, 10.1)."

But if that were true, in Mesozoic Saurischia it would also invalidate e.g. Brachyrostra, Furileusauria, Pantyrannosauria, Eutyrannosauria, (usually) Microraptoria, Eudromaeosauria, Diplodocimorpha, Khebbashia, and potentially a lot of titanosaur groups (Lithostrotia, Diamantinosauria, Colossosauria, Lognkosauria, Eutitanosauria, Rinconsauria) compared to Titanosauroidea and/or Saltasauroidea.

ICZN Article 35.1 does say "The family group encompasses all nominal taxa at the ranks of superfamily, family, subfamily, tribe, subtribe, and any other rank below superfamily and above genus that may be desired..." and Article 29.2 says " The suffix -OIDEA is used for a superfamily name, -IDAE for a family name, -INAE for a subfamily name, -INI for the name of a tribe, and -INA for the name of a subtribe. These suffixes must not be used at other family-group ranks. The suffixes of names for taxa at other ranks in the family-group are not regulated", so the fact these end in -A, -IA, -IMORPHA etc. doesn't seem to disqualify them from being family-group names as long as they're not superfamilies, families, subfamilies, tribes or subtribes. Which contradicts Article 11.7.1.3. that says all family-group names must "end with a family-group name suffix." 

So you could argue 29.2 is as valid as 11.7.1.3, but Article 11.7.1.1 (names must "be a noun in the nominative plural formed from the stem of an available generic name") would still invalidate e.g. Brachyrostra, Furileusauria, Khebbashia, Lithostrotia and Colossosauria even if you argue e.g. Eutyrannosauria and Pantyrannosauria are eponyms of Tyrannosaurus (which I'm skeptical of). 

For completion's sake, Article 16.2 is "In addition to satisfying the provisions of Articles 13-15, a new family-group name published after 1999 must be accompanied by citation of the name of the type genus (i.e. the name from which the family-group name is formed)", which is probably the case in all of these eponymous examples.

Thoughts?

Mickey Mortimer

[Thomas Richard Holtz]

Mickey, I found that one of the strangest parts of the paper, and one that shouldn't have survived review with reviewers or editors who know the scope of current taxonomy in many groups, not just dinosaurs!

I would have agreed that had the term been "Australokritosaurina" or something like that, they would have had a better case. But the construction of that name demonstrates it was not coined to conform to the traditional Linnaean family-group names, which have a standard set of suffices (-oidea, -idea, -inae, -ini, -ina).

Personally, I admit I like "secernosaurs" (or "Secernosaurina" as a tribe in Kritosaurini) better than the name "Australokritosauria". But personal preference isn't a factor here.

Anyway, that's my first thoughts on it.

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[Mickey Mortimer]

Actually thinking about it further, isn't the obvious answer that Austrokritosauria and such are NOT RANKED? Thus they cannot be family-group taxa, and so are not bound by the ICZN. Brachyrostra and Furileusauria HAPPEN to fall between superfamily Abelisauroidea and genus Abelisaurus in the consensus phylogeny, but they don't HAVE to. Unlike Abelisauridae at family rank. So I guess it was a stupid question, though it did get past "the editor-in-Chief, Dr Susannah Maidment, ...
and ... the two reviewers, Henry Sharpe and Liz Freedman Fowler", unless the authors ignored their advice about it.

Mickey Mortimer

[Thomas Richard Holtz]

" isn't the obvious answer that Austrokritosauria and such are NOT RANKED? Thus they cannot be family-group taxa, and so are not bound by the ICZN."

I intended to actually state that, but forgot to actually put it in my comment. Definitely agree on this!

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