Barta and Norell 2021
give us a detailed look at every bone in the basal ornithischian, Haya griva (Fig. 1). We looked at Haya earlier here and nested it close to Pisanosaurus in the large reptile tree (LRT, 1810+ taxa).
Figure 1. Haya in lateral view.
For reasons unknown
Barta and Norell did not include Chilesaurus and Daemonosaurus (Fig. 2) in their text or phylogenetic analysis.
Figure 1. Skulls of Daemonosaurus, Haya and Jeholosaurus to scale.
The hypothesis of interrelationships
that nested Chilesaurus and Daemonosaurus as phytodinosaurs basal to Ornithischia (Fig. 2) has been online since 2011.
Figure 2. Subset of the LRT focusing on the Phytodinosauria with Buriolestes at its base.
No matter how much detail you put into your study of a taxon
it is all for naught if you decide to exclude pertinent taxa. You will not understand the phylogeny of that taxon, how it relates to others. Haya is a basalmost ornithischian in the LRT, an hypothesis of interrelationships not confirmed by Barta and Norell due to taxon exclusion. They had a chance to deliver big news and muffed it.
The Barta and Norell cladogram suffered from massive loss of resolution
at many nodes. Never a good sign. If you can tell two taxa apart generically, as fossils, you should be able to lump and separate them in a cladogram.
Perhaps too many incomplete taxa were tested.
Don’t include incomplete taxa until you have your tree topology all worked out first.
References
Barta DE and Norell MA 2021. The osteology of Haya griva (Dinosauria: Ornithischia) from the Late Cretaceous of Mongolia. Bulletin of the American Museum of Natural History 445: 1-111.
