A new silesaurid from Carnian beds of Brazil does NOT fill a gap in the radiation of avian line archosaurs

Müller and Garcia 2023 report,
“Comprising the oldest unequivocal dinosauromorphs in the fossil record, silesaurs play an important role in the Triassic radiation of dinosaurs. These reptiles provide the main source of information regarding the ancestral body plan of dinosaurs, as well as the basis for biogeographic models.”

Figure 1. Poposaurs in the LRT to scale. Silesaurus nests here with similar taxa.

This is incorrect.
By adding traditionally omitted taxa Silesaurus (Fig 1) moves into the Poposauria (Figs 1, 2), a clade outside the definition of the Archosauria. In Müller and Garcia 2023, the poposaurs Turfanosuchus, Poposaurus, Lotosaurus, Shuvosaurus and Effigia are not mentioned in the text. Likewise not mentioned are basal bipedal members of the Crocoylomorpha: Saltoposuchus, Trialestes, Junggarsuchus, Pseudhesperosuchus and Carnufex. These, by definition, are sisters to the Herrerasauridae, the basalmost dinosaurs. They should not be omitted. The authors mention ‘pterosauromorphs’, but adding pertinent taxa moves pterosaurs into the Lepidosauria. Only academically sanctioned taxon omission keeps mythical traditions like this alive.

When Müller and Garcia refer to silesaurids as, “the oldest unequivocal dinosauromorphs” this should mean this hypothesis of interrelationships has been verified by all competing phylogenetic analysis, moving into the realm of theory and fact. In counterpoint, by simply adding omitted taxa, the LRT invalidates the Müller and Garcia hypothesis of interrelationships. As scientists Müller and Garcia should welcome this challenge and attempt to replicate results with a similar, more inclusive taxon list so they don’t make this mistake again.

Figure 2. Subset of the LRT focusing on Crocodylomorpha with the addition of Alligatorellus. Unlabeled Poposauria (Turfanosuchus to Effigia) is the outgroup clade to the Archosauria.

The only “avian-line archosaurs”
are members of the Theropoda in the large reptile tree (LRT, 2250 taxa, subset Fig 2). The LRT minimizes taxon exclusion by including traditionally omitted taxa. The LRT recognizes no clade “Dinosauromorpha” because only Dinosauria + Crocodylomorpha = Archosauria in the LRT.

If you want to test the LRT
build your own wide gamut cladogram with a similar taxon list and whatever 200+ traits you want to use. Then you’ll be able to confirm, refute or modify this hypothesis of interrelationships (subset Fig 1).

References
Müller RT and Garcia M 2023. A new silesaurid from Carnian beds of Brazil fills a gap in the radiation of avian line archosaurs. Scienctific Reports 13:4981. https://doi.org/10.1038/s41598-023-32057-x