From the Wallace et al. 2019 abstract:
“We describe a new probainognathian cynodont, Pseudotherium argentinus, from the early Late Triassic Ischigualasto Formation of Argentina.”
In the large reptile tree (LRT, 1559 taxa) Pseudotherium (Fig. 1) nests between Haldanodon and Pachygenelus, pretty close to where Wallace et al. nest their new taxon (Fig. 2). Haldanodon is not mentioned in their text. All are descendants of probainognathian cynodonts, so they nailed it! As noted by the authors, the 3D skull of Pseudotherium adds greatly to the dataset of a typically crushed bunch of sister taxa.
Wallace et al. report,
“Our analysis found weak support for Pseudotherium as the sister taxon of Tritylodontidae.”
Not true according to the LRT. More basal in the LRT.
Wallace et al. also report,
“Thus, Pseudotherium may lie just inside or just outside of Mammaliamorpha, and there is also weak character support for its sister taxon relationship with Brasilitherium.”
Not true according to the LRT where Brasilitherium lies in the ancestry of the platypus, Ornithorhynchus, within the Prototheria, within the Mammalia. Pseudotherium nests basal to Pachygenelus in the LRT.
This was an excellent paper, with lots of details.
Adding a few more taxa would have helped, but just a little.
Wallace RVS, Martinez R and Rowe T 2019. First record of a basal mammailiamorph form the early Late Triassic ischigualasto Formation of Argentina. PLoS ONE 14(8): e0218791. https://doi.org/10.1371/journal.pone.0218791