Müller et al. 2018
describe a new dinosaur skeleton they attribute to Buriolestes shultzi (Cabreria et al. 2016, ULBRA-PVT280, Figs. 2, 3). In the large reptile tree (LRT, 2015 taxa; subset Fig. 1) the holotype now nests at the base of the Phytodinosauria. The referred specimen is different enough to nest between the herrerasaurs and all other dinosaurs. This, of course, removes herrerasaurs from the definition of the Dinosauria (Passer + Triceratops, their last common ancestor (= CAPPA/UFSM 0035) and all descendants).
Buriolestes schultzi (Cabreria et al. 2016; Late Triassic, Carnian; 230mya) was originally and later (Müller et al. 2018) considered a carnivorous sauropodomorph, but here two specimens nest as the basalmost dinosaur (CAPPA/UFSM 0035) and the basalmost phytodinosaur (ULBRA-PVT280).
All cladograms agree that Buriolestes
is a very basal dinosaur. Taxon exclusion changes the tree topology of competing cladograms. The broad autapomorphic ‘eyebrow’ of the CAPPA specimen indicates it is a derived trait in this Late Triassic representative of an earlier genesis.
The Müller et al. cladogram
combined both specimens attributed to Buriolestes (never a good idea, but it happens all the time). The Müller et al. cladogram excluded a long list of basal bipedal crocodylomorpha, but did include Lewisuchus. It excluded the archosaur outgroups PVL 4597, Turfanosuchus and Decuriasuchus. The Müller et al. cladogram nested Ornithischia basal to Saurischia (= Herrerasauridae + Agnophitys, Eodromaeus, Daemonosaurus + Theropoda + Sauropodomorpha) with Buriolestes nesting between Eoraptor and Panphagia. The CAPPA specimen of Buriolestes is also a sister to the basalmost theropod, Tawa (Fig. 3)… and not far from the other basal archosaur, Junggarsuchus (Fig. 4).
Cabreira SF et al. (13 co-authors) 2016. A unique Late Triassic dinosauromorph assemblage reveals dinosaur ancestral anatomy and diet. Current Biology (2016), http://dx.doi.org/10.1016/j.cub.2016.09.040
Müller RT et al. (5 co-authors 2018. Early evolution of sauropodomorphs: anatomy and phylogenetic relationships of a remarkably well-preserved dinosaur from the Upper Triassic of southern Brazil. Zoological Journal of the Linnean Society, zly009 (advance online publication) doi: https://doi.org/10.1093/zoolinnean/zly009