Sanxiasaurus calls into question ornithischian interrelations 

The announcement of the discovery
of the ornithischian, Sanxiasaurus (Ning et al. 2019; Fig. 1) calls into question the topology of the Ornithischia. What are the outgroup taxa and clades? Which are the basalmost taxa?

Figure 1. Ornithischia from Ning et al. Overlay lists missing taxa and outgroups from the LRT (see Fig. 2).

Figure 1. Ornithischia from Ning et al. Overlay lists missing taxa and outgroups from the LRT (see Fig. 2). Evidently the name Sanxiaosaurus above is a typo from the original graphic.

The trouble is
Ning et al. failed to include a long list of outgroup and basal taxa (Figs. 1, 2). So, what are the ramifications?

Figure 2. Subset of the LRT focusing on the Phytodinosauria.

Figure 2. Subset of the LRT focusing on the Phytodinosauria. Take a look at the outgroup for the Ornithischia and basalmost taxa, then see how many are included in figure 1.

As usual,
topologies can change when you add pertinent taxa and delete irrelevant taxa. You can only know which is which when you start with a wide enough gamut cladogram. Only then can you have confidence that your subsets are indeed monophyletic.


References
Ning Li, et al. (11 co-authors) 2019.
 A neornithischian dinosaur from the Middle Jurassic Xintiangou Formation of Yunyang, Chongqing, China: the earliest record in Asia. Historical Biology (advance online publication)
doi: https://doi.org/10.1080/08912963.2019.1679129
https://www.tandfonline.com/doi/full/10.1080/08912963.2019.1679129

wiki/Sanxiasaurus

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