WWD: "Sphenodont"
Added 2023-07-12 06:53:58 +0000 UTCBecause I assume they were trying to save money in this episode, one of the animals is just stock footage of a tuatara hunting a giant weta. Neither animal is actually known from the region, their presence is inferred through their fossil record and modern geographical distribution. This is therefore the most speculative member of the cast in the episode considering it technically does not exist. For this reason I was reluctant to add it, but for the sake of completion I've included one here, because even if it's made-up, it's still plausible enough.
Rather than just being a one-to-one modern tuatara, this depiction is based on the South American sphenodont genera, Priosphenodon and Kaikaifilusaurus (not to be confused with the mosasaur genus Kaikaifilu), which would have existed at around the same time the episode is set. South America was connected to Australia via Antarctica at the time, so it's reasonable for them to be present there too. Far from being a clone of the modern tuatara, these were quite large, at over a meter in length, more than twice the size of modern tuataras, had a beak-like projection, and were herbivorous, possibly filling a niche now occupied by iguanas. Rather than showing tuataras as an archaic living fossil, it would show how the group had once been highly diverse and successful (including once having marine species).
I've given it quite a fat and chubby tail as an adaptation for the highly seasonal climate; gorging itself on tender vegetation and insects in the summer, it retreats into a burrow in the winter and survives for months on its fat reserves in a state of hibernation. Modern tuataras can survive quite cold conditions, particularly for an ectothermic reptile, but it's unclear if this was the case back during the Mesozoic, when the Earth was overall much warmer.
