The Enigmatic Sikannisuchus

Sikannisuchus huskyi (Nicholls, Brinkman and Wu 1998) was originally described as a large (est. 4 m long) archosaur from the Upper Triassic of British Columbia. It had a broad, flat skull (posterior only is known), a lateral mandibular fenestra, laterally compressed, serrated teeth, elongate transverse processes, neural spine table, osteoderms and thecodont dentition. The postfrontal was reported to enter the borders of both the orbit and upper temporal fenestra. The large prefrontal contacted both the nasal and postfrontal, excluding the frontal from the orbit margin. The authors were unable to assign the specimen to any taxon within the Archosauria.

Sikannisuchus

Figure 1. Sikannisuchus skull in dorsal view. Present interpretation (colorized bones). As originally interpreted (line drawing). Dorsal view of Postosuchus skull for comparison with bones colorized and not to scale.

Phylogenetic analysis
Adding Sikannosuchus to the present large reptile family tree nests it basal to Revueltosaurus and Postosuchus within the Rauisuchidae. Smok is the outgroup taxon. That nesting makes sense chronologically and size-wise. Contact between the prefrontal and postfrontal remains an autapomorphy, but please note we’re also seeing wide variation in this subclade of four flat-headed taxa.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Nicholls EL, Brinkman DB, and Wu X-C 1998. A new archosaur from the Upper Triassic Pardonet Formation of British Columbia. Canadian Journal of Earth Sciences 35: 1134–1142.

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