Taxon exclusion and lack of simple oversight
has once again produced a cladogram (Fig. 1) of untenable relationships. And it got published (Ezcurra and Butler 2018). So many taxa are missing… so many untested assumptions are present… so many ‘by default’ nestings… so many impossible sisters.
This paper basically repeats errors
from earlier works (Nesbitt 2011, Ezcurra 2016).
The Archosauromorpha is defined as
taxa closer to archosaurs than to lepidosaurs. In the large reptile tree (LRT, 1236 taxa) that split follows the basalmost amniote/reptiles, Gephyrostegus and Silvanerpeton. The latter is from the Viséan (Early Carboniferous). A series of amphibian-like reptiles nest at the base of the new Archosauromorpha. This hypothesis of relationships is completely lost on Ezcurra and Butler due to taxon exclusion on a massive scale, following their traditional untested hypotheses of relationships.
When you add more relevant taxa
you will find that the white taxa in figure 1 nest on the lepidosauromorph branch of your greatly expanded tree, while the yellow taxa nest on the archosauromorph branch. And many taxa will fill the gaping morphological gaps present here.
many clades, including the Lepidosauromorpha and the Archosauromorpha, recovered from the devastating Permo-Triassic mass extinction event. No argument there.
016.The phylogenetic relationships of basal archosauromorphs, with an emphasis on the systematics of proterosuchian archosauriforms. PeerJ 4:e1778https://doi.org/10.7717/peerj.1778
Excurra MD and Butler RJ 2018.The rise of the ruling reptiles and ecosystem recovery from the Permo-Triassic mass extinction. Proceedings of the Royal Society B Biological Sciences. DOI: 10.1098/rspb.2018.0361
Nesbitt SJ 2011. The early evolution of archosaurs: relationships and the origin of major clades. Bulletin of the American Museum of Natural History 352:1–292 DOI 10.1206/352.1.