Thilastikoischia is a large order derived from modern day iguanas. Their name means "Mammal Hipped", because of their similar leg structure to mammals. They are a new group, having appeared in 65 Myf, but have diversified since then. Most are swift, fleet- footed herbivores, filling similar niches to deer and antelopes of the modern era. They are the most numerous herbivores in Borealia, being found all over the supercontinent, in various sizes and forms.
Edit: I apologize if this seems rushed and, well, "not as good", as my other works. I only recently came up with this idea and I will continue on it in the future.