New big Shansisuchus – close to Garjainia

Shansisuchus is a small erythrosuchid (Fig. 1) immediately identified by its very large subnarial fenestra between the naris and the antorbital fenestra. It looks like it has two antorbital fenestra, one before the other. The holotype (IVPP V2503,Young 1964) is a little less than 2 m in length.

erythrosuchid

Figure 1. Erythrosuchids. Click to enlarge. Long-legged Vjushkovia was basal to rauischids and the line that led to archosaurs.

A new specimen (Wang et al. 2013) from the Late Middle Triassic is quite a bit larger and more like Garjainia, it’s sister taxon.

Figure 2. The holotype Shansisuchus (below) and the new one (above) both to scale.

Figure 2. The holotype Shansisuchus (below) and the new one (above) both to scale. The 9 cervicals are green. The estimated 19 dorsals are red. The big intercentra are yellow. Those are pretty big cervical ribs. This reptile was big overall, seemingly a new genus nesting close to Shansisuchus.

Wang et al. (2013) note the premaxilla bears 6 teeth, unique among erythrosuchids. The naris is close to the midline and rather small. The skull is very narrow, as in other erythrosuchids.

In my opinion, the two specimens are not conspecific and perhaps not congeneric.

Wang’s phylogenetic analysis includes several taxa that just don’t belong including, Mesosuchus and Dimorphodon (lepidosaurs), Vancleavea (thalattosaur) and Chanaresuchus (pararchosauriform). Otherwise the tree echoes the the large reptile tree (and most every other study) in nesting Shansisuchus with erythrosuchids (Garjainia not included and close to Fugusuchus, Osmolskina and Euparkeria.

These erythrosuchids appear to have been like hippos of the Triassic, but carnivorous. It would be interesting to know if the new specimen bore large running legs or short wading ones. Recently we looked at the resemblance of the basal erythrosuchid Garjainia to Youngina, the phylogenetic ancestor. Youngina belongs at the base of archosauriform analyses, not Mesosuchus.

References
Wang R-F, Xu S-C, Wu X-C, Li C and Wang S-Z 2013. A New Specimen of Shansisuchus shansisuchus Young, 1964 (Diapsida: Archosauriformes) from the Triassic of Shanxi, China. Acta Geologica Sinica (English Ed.) 87(5):1185-1197.
Young C-C 1964. The pseudosuchians in China: Palaeontologia Sinica 151, new series C., 9:1-205.

wiki/Shansisuchus

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