Müller and Garcia 2020 cast doubt
on all prior hypotheses of origin for the herbivorous dinosaur clade, Ornithischia.
From the abstract:
“Whereas ornithischian dinosaurs are well known from Jurassic and Cretaceous deposits, deciphering the origin and early evolution of the group remains one of the hardest challenges for paleontologists.”
No, it’s not. That problem was solved nine years ago. In the large reptile tree (LRT, 1729+ taxa; subset Fig. 1) Ornithischia + Sauropodomorpha arise from primitive phytodinosaurs like Eodromaeus, Barberenasuchus and Buriolestes. Tell Müller and Garcia to keep adding taxa. They have too few.
The cladogram in Müller and Garcia 2020
suffers from massive taxon exclusion. Incredibly, the basal ornithischians, Chilesaurus and Jeholosaurus (Figs. 1, 2) are not mentioned in the text. Surprising how anyone can discuss the origin of a clade without including its basalmost members?
To their credit, the authors do not mention pterosaurs.
To their discredit, the authors are still trying to push the invalidated relationship between the poposaur dino-mimic, Silesaurus, and the clade Ornithischia.
To their discredit, the authors omit all of the basal bipedal crocodylomorph sisters to Lagosuchus.
Due to taxon exclusion, the authors recover a traditional and invalid Saurischia / Ornithischia dichotomy. Add taxa to solve that problem.
A few reconstructions would have helped the authors identify several taxonomic mismatches.
You can access the Müller and Garcia 2020 paper
and get a free PDF here.
Müller RT and Garcia MS 2020. A paraphyletic ‘Silesauridae’ as an alternative hypothesis for the initial radiation of ornithischian dinosaurs. Biology Letters 16(8): 20200417. doi: 10.1098/rsbl.2020.0417