Azhdarchoidea phylogeny revised

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

A new paper:

Henry N. Thomas & Skye N. McDavid (2025)
Enter the dragons: the phylogeny of Azhdarchoidea (Pterosauria: Pterodactyloidea) and the evolution of giant size in pterosaurs
Journal of Systematic Palaeontology 23(1): 2569368
doi: https://doi.org/10.1080/14772019.2025.2569368
https://www.tandfonline.com/doi/full/10.1080/14772019.2025.2569368


Azhdarchidae is a clade of pterosaurs which includes the largest-ever flying animals. The evolutionary history of this clade and its closest relatives remains incompletely understood and highly debated. To investigate this, we combined multiple preexisting datasets with 29 new operational taxonomic units and 57 new characters, resulting in the most comprehensive phylogenetic analysis of pterosaurs published to date, with a focus on Azhdarchomorpha. Higher level phylogenetic taxonomy of Azhdarchomorpha is revised based on the results of this analysis, and three new clade names are established: Shenzhoupterinae (cl. nov.) for the subgroup of Chaoyangopteridae containing Shenzhoupterus that is sister to the existing Chaoyangopterinae; Concilazhia (cl. nov.) for the clade uniting Chaoyangopteridae and Azhdarchiformes; and Serpennata (cl. nov.) for the clade with highly elongated cervical series that includes the giant (∼10 m wingspan) Quetzalcoatlus and Arambougiania. The iconic genus Quetzalcoatlus is recovered as polyphyletic, with its giant and moderately large species belonging to separate clades within Serpennata. Gigantism evolved convergently at least four times in quetzalcoatline azhdarchids: in Cryodrakon, once in a clade containing Hatzegopteryx and its closest relatives, and twice independently in different lineages of Serpennata.

[Mickey Mortimer]

The authors say "‘Neopterodactyloidea’ was defined by Andres et al. (2014) as “the least inclusive clade containing Quetzalcoatlus northopi Lawson [1975b] and Chaoyangopterus zhangi Wang and Zhou [2003]”. This violates PhyloCode Art. 11.9 as the clade name is derived from Pterodactylus, which is not part of this clade under the topology of Andres et al. (2014), and was universally recovered as a much more early-diverging member of Pterodactyloidea in then-preexisting analyses ... . ‘Neopterodactyloidea’ is not an acceptable name for this clade under the PhyloCode."

But that's not technically correct, right? Pterodactylus is not the eponym of Neopterodactyloidea, the non-existent 'Neopterodactylus' would be. Just like the eponym of Eustreptospondylidae is not Streptospondylus and the eponym of Proceratosauridae is not Ceratosaurus. It doesn't even make sense etymologically, because the new radiation of pterodactyloids shouldn't logically need to include Pterodactylus itself. 

And before somebody objects to Neopterodactyloidea existing because a family-level name needs to be based on a genus, it was specifically erected as "(new clade name)" not superfam. nov..

Mickey Mortimer

[Ethan Schoales]

Are non-family level clades allowed to end in family-level suffixes like -oidea?

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[Tim Williams]

I would say _Pterodactylus_ is indeed the eponym of Neopterodactyloidea, albeit indirectly.  Pterodactyloidea takes its name from _Pterodactylus_, and Neopterodactyloidea takes its name from Pterodactyloidea.  So I agree with the authors.

Besides, Concilazhia is a much better clade name than Neopterodactyloidea in my opinion.

While on the topic of clade names, I really like the name Serpennata - well-thought-out and very apt: "Portmanteau of the Latin _serpens_ meaning ‘snake’ and ‘pennata’ (fem.) meaning ‘feathered’ (Gaffiot, 1934). ‘Feathered serpents’, in allusion to the extremely long cervical series of azhdarchids in this clade, and to the internal specifier _Quetzalcoatlus_, named for the Aztec deity Quetzalcoatl, depicted as a flying feathered serpent."

Finally (and unrelated to clade names) - am I correct in interpreting that _‘Palaeornis’ cliftii_ is now regarded as a valid species of pterosaur?  I mean in a diagnostic sense.  The genus name is obviously preoccupied.  I had wondered if 'Paleornithis' is available - Mantell mentions the name after he realized that his _Palaeornis_ was preoccupied, but before he accepted _P. cliftii_ was a pterosaur and not a bird.  But after reading Witton et al. (2009), the status of the name 'Palaeornithis_ appears to be too ambiguous. 

[Tim Williams]

Ethan Schoales <ethan.s...@gmail.com> wrote:
 
> Are non-family level clades allowed to end in family-level suffixes like -oidea? 

I guess so.  It happens quite often.  There's echinoderm classes that end in -oidea, with names that are entirely descriptive, e.g., Asteroidea ("star-like"), Crinoidea ("lily-like").

For mammals there is the order Hyracoidea for hyraxes (there is no family Hyracidae).  There is also Anthropoidea as a clade of 'higher' Primates - but I believe nowadays Simiiformes is preferred.

Having the suffix -oidea invites the potential for a clade to be treated as a superfamily when it's not intended to belong to a family group of taxa.  I understand it's for this reason that many orders of insects end in -odea rather than -oidea (Blattodea, Mantodea, Grylloblattdea, Psocodea, etc).

[Ethan Schoales]

Yeah, using a family-group suffix for a non-family group name might just be confusing. If you use ranks at all, that is…

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[Mickey Mortimer]

Well technically, the Phylocode doesn't use the word eponym. It says "name derived from the stem of a typified name", which would be the entire first part before the inflected ending. It's like Crocodylotarsi, where Crocodylus is the inspiration for the word, but is not the stem because -tarsi is not an inflection any more than Neo- is. For Neopterodactyloidea-style examples accepted officially by PhyloCode-

"Euiguanodontia Coria & Salgado, 1996 minimum-clade min ∇ (Camptosaurus dispar (Marsh, 1879) & Dryosaurus altus (Marsh, 1878) & Gasparinisaura cincosaltensis Coria & Salgado, 1996 | ~ Tenontosaurus tilletti Ostrom, 1970)"

"Neoceratopsia Sereno, 1986 maximum-clade max ∇ (Triceratops horridus Marsh, 1889 ~ Chaoyangsaurus youngi Zhao, Cheng & Xu, 1999 & Psittacosaurus mongoliensis Osborn, 1923)"

Mickey Mortimer

[R. Pêgas]

I don't think the stem is a "hypothethical Neopterodacylus". The stem is pterodactyl-. Neo is a prefix, and oidea is a suffix. Given the name is obviously inspired by the name Pterodactyloidea, then neo is just a prefix. I guess the logic of Thomas and McDavid makes sense.

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[Skye McDavid]

I'm a bit late to respond, but here are our thoughts on "Palaeornis" cliftii:

First, just because something has sufficient features to place it phylogenetically does not necessarily mean that is a valid or diagnostic taxon. 

The holotype of "Palaeornis" cliftii is a partial humerus (proximal and distal ends with the midshaft missing) which is enough to place it as the sister taxon to Tapejaridae. 

Whether this is enough to satisfactorily diagnose a species remains to be seen. We chose not to comment on the potential validity of this species (as we did for Bennettazhia) since we hadn't seen the holotype in person yet. We did actually look at the holotype last week along with lots of other British pterosaur material... results pending while we crunch all our new data.

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Skye McDavid

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