Originally Gulosaurus was thought to be either Grippia longirostris or Parvinatator wapitiensis, but as the fossil was incomplete it was uncertain which. In 2013, the other half of the fossil, including its skull, was discovered and this proved it to be a new species entirely, closely related to Grippia and very similar.
Features
Overall, Gulosaurus was similar to Grippia. It was the same size, around 1.5 meters long, and much of the skeleton was the same, namely the ribs and centrum discovered. Also like Grippia, it had pentadactyl limbs rather than exhibiting polyphalangy, as many later ichthyopterygians did. Most of the flipper structure was very similar apart from the first metacarpal, which had a notched peripheral shaft in Gulosaurus but was lunate in Grippia. The skull of Gulosaurus was also very different to that of Grippia - it had cylindrical anterior teeth, although as no Grippia snouts have been discovered, it remains unknown if this was different. The skull also exhibited postfrontal-frontal contact at the rostral limit of the anterior margin of the supratemporal terrace.[2]
Phylogeny
Below is a cladogram modified from Cuthbertson et al., 2013.[2]
^ abcCuthbertson, R. S.; Russell, A. P.; Anderson, J. S. (2013). "Cranial morphology and relationships of a new grippidian (Ichthyopterygia) from the Vega-Phroso Siltstone Member (Lower Triassic) of British Columbia, Canada". Journal of Vertebrate Paleontology. 33 (4): 831–847. doi:10.1080/02724634.2013.755989. S2CID131501541.
