You heard it here first: Faxinalipterus was not a Triassic pterosaur

Kellner et al. 2022 reassess a taxon known
from only a few scattered bones, Faxinalipterus (Bonaparte 2010) originally described as a basal pterosaur. Some bones were more extensively exposed for this study. Others were µCT scanned for the first time. Kellner et al no longer consider Faxinalipterus a pterosaur (contra Bonaparte 2010). Readers heard that here first online in 2013, about nine years ago.

Faxinalipterus matched to Scleromochlus. The former is more primitive, like Gracilisuchus, in having shorter hind limbs and more robust fore limbs. The maxilla with fenestra and fossa, plus the teeth, are a good match.
Figure 1. Faxinalipterus matched to Scleromochlus in 2013. The former is more primitive, like Gracilisuchus, in having shorter hind limbs and more robust fore limbs. The maxilla with fenestra and fossa, plus the teeth, are a good match. In 2022 Faxinalipterus was split into two genera.

Back in 2013, with too few bones for testing in the LRT,
Faxinalipterus was matched to the basal bipedal crocodylomorph, Scleromochlus (Fig 1), a taxon omitted from both papers (Bonaparte 2010, Kellner et al. 2022). Virtually every aspect of Faxinalipterus seems to be a good match, including chronological age and overall size. Faxinalipterus is more primitive in having shorter hind limbs and more robust front limbs, as in the Scleromochlus relative, Gracilisuchus (Fig 1 upper right).

The biggest problem with Faxinalipterus studies continues to be taxon exclusion.
Kellner et al. follow other authors in excluding Scleromochlus (Fig. 1) and bipedal basal crocodylomorphs from their analyses. The authors also omit bipedal members of the Fenestrasauria (Peters 2000), Langobardisaurus, Cosesaurus, Sharovipteryx and Longisquama. These taxa are known from complete skeletons and they nest with pterosaurs in several analysis (Peters 2000). These, in turn, nest with lepidosaurs (Peters 2007, LRT), far from archosaurs. With these determined taxonomic exclusions Kellner et al. 2022 ignominiously enters the professionally embarrassing timeline of pterosaur origin studies.

Kellner et al. discuss a humerus and scapulocoracoid
(MCZ 10152) McCabe and Nesbitt 2021 assigned to Lagerpeton. Earlier the possibility of a connection with Procompsognathus (Fig 2) was considered. It’s an excellent match. Even so, always beware of chimaeras. Previous authors omitted Procompsognathus from their studies.

Figure 4. Procompsognathus has proportions that precisely fit the MCZ 101542 material.
Figure 2. Procompsognathus had proportions that precisely fit the MCZ 101542 material shown here as a color photo.

From the Kellner et al. abstract:
“Our interpretations on the identity of several bones differ from those of the original description, and we found no support favoring pterosaur affinities for the taxon.

Confirmation of the 2013 hypothesis. Good to hear.

The maxilla previously referred to Faxinalipterus minimus is disassociated from this taxon and referred to a new putative pterosauromorph described here from a partial skull and fragmentary postcranial elements. Maehary bonapartei gen. et sp. nov. comes from the same fossiliferous site that yielded Faxinalipterus minimus, but the lack of overlapping bones hampers comparisons between the two taxa.

At times like this, a third, more complete taxon, with parts that overlap both enigma taxa, can resolve such issues. Unfortunately, Kellner et al. 2022 omitted a suitable third taxon, Scleromochlus (Fig 1) despite this solution appearing online for the last 9 years.

As longtime readers realize, and the pterosaur origin timeline documents, this is how pterosaur workers operate. They omit without testing and thereby keep their blinders on. Each one seeks their own hopeful headlines while ignoring competing citations.

Our phylogenetic analysis places Faxinalipterus minimus within Lagerpetidae and Maehary bonapartei gen. et sp. nov. as the earliest-diverging member of Pterosauromorpha.”

Their phylogenetic analysis cherry-picks taxa and omits actual pterosaur ancestors, which Peters 2000 labeled Fenestrasauria. ‘Pterosauromorpha’ is a junior synonym for Reptilia in the LRT which tests all competing candidates. Faxinalipterus is related to the crocodylomorph archosaur, Scleromochlus, not to the pterosaur lepidosaurs.

Figure 3. Skull elements from Faxinalipterus transferred to Maehary by Kellner et al. 2022. The authors did not realize the palate bone was a taphonomically jumbled collection (bottom grayscale image) here digiitally segregated (middle colored image). Compare this reconstructed palate to the one in Scleromochlus.

Have you noticed the emerging geographic patterns
in pterosaur origin studies? The English prefer their own Scleromochlus to the exclusion of lagerpetids. South Americans prefer their own lagerpetids to the exclusion of Scleromochlus.

Colleagues. please stop wasting your time
trying to re-discover the ancestry of pterosaurs by cobbling together bits and pieces of unrelated taxa. Please stop omitting the complete skeletons that have already been shown to be ancestral to pterosaurs (Peters 2000) just because you can, and your editor David Hone, will let you. Please stop hoping/pretending that Lagerpeton and kin are close to pterosaurs and dinosaurs. Adding taxa moves Lagerpeton close to the proterochampsid Tropidosuchus (Novas and Agnolin 2016) as confirmed by South American workers here.

Every one of these silly attempts at finding pterosaur ancestors
where you want them, instead of where they are, just makes the paleo profession look less scientific and more desperate for attention while maintaining a smokescreen of elitism. No matter how you feel about ‘the messenger’ don’t omit the taxa. Go study them. They exist.

Bonaparte JF, Schultz CL and Soares MB 2010. Pterosauria from the Late Triassic of southern Brazil. In S. Bandyopadhyay (ed.), New Aspects of Mesozoic Biodiversity, Lecture Notes in Earth Sciences 132:63-71.
Kellner AWA, Holgado B, Grillo O, Pretto FA, Kerber L, Pinheiro FL, Soares MB, Schultz CL, Lopes RT, Araújo O, Müller RT 2022. Reassessment of Faxinalipterus minimus, a purported Triassic pterosaur from southern Brazil with the description of a
new taxon. PeerJ 10:e13276
McCabe MB and Nesbitt SJ 2021. The first pectoral and forelimb material assigned to the lagerpetid Lagerpeton chanarensis (Archosauria: Dinosauromorpha) from the upper portion of the Chañares Formation, Late Triassic. Palaeodiversity, 14(1) : 121-131.
Novas FE and Agnolin FL 2016 Lagerpeton chanarensis Romer (Archosauriformes): A derived proterochampsian from the middle Triassic of NW Argentina. Simposio. From Eventos del Mesozoico temprano en la evolución de los dinosaurios”. Programa VCLAPV. Conferencia plenaria: Hidrodinámica y modo de vida de los primeros vertebrados. Héctor Botella (Universitat de València, España) 2016
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany p 27.


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