The Enigmatic Teraterpeton

Updated November 16, 2014 with new illustrations and text reflected a relationship with Diandongosuchus, which was published after this blog post was originally presented.

Teraterpeton hrynewichorum (Sues 2003) Late Triassic, ~215 mya, Figs. 1, 2), was described as euryapsid (lacking a lateral temporal fenestra) and possibly related to the rhynchocephalian, Trilophosaurus, on that basis. Here Teraterpeton nests as a sister to Diandongosuchus (Fig. 2), not far from parasuchians, with a stretched out rostrum and far fewer, smaller teeth. The lateral temporal fenestra was largely blocked by the large quadrate. The antorbital fenestra was much larger here than in sister taxa due to the confluence of the naris.

Figure 2. Teraterpeton skull. Note the confluent naris/antorbital fenestra.

Figure 2. Teraterpeton skull. Note the confluent naris/antorbital fenestra.

Distinct from Diandongosuchus, the skull had a narrower configuration in dorsal view. The pedal(?) unguals were robust, but note the disparate sizes, perhaps used for digging.

Figure 1. Diandongosuchus (above) compared to Teraterpeton (below). Note the similar scapula shapes and the way the posterior dorsal ribs terminate in a line. Both lack the flaring cheeks of parasuchians and Youngina. Teraterpeton, with so few teeth, could well have been a plant eater or anything but a carnivore. Hopefully we'll find more of this genus someday.

Figure 1. Diandongosuchus (above) compared to Teraterpeton (below). Note the similar scapula shapes and the way the posterior dorsal ribs terminate in a line. Both lack the flaring cheeks of parasuchians and Youngina. Teraterpeton, with so few teeth, could well have been a plant eater or anything but a carnivore. Hopefully we’ll find more of this genus someday.

There is not much to go on with this specimen, but the few clues we do have indicate that Teraterpeton was a strange sort of quasi-parasuchid and with so few teeth, likely an herbivore.

References
Sues H-D 2003. 
An unusual new archosauromorph reptile from the Upper Triassic Wolfville Formation of Nova Scotia. Canadian. Journal of Earth Science 40(4): 635-649.

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