I'm looking for a bit of inspiration to help me with a bit of writer's block I've got going on at the moment.
In my novel, "A Tale of Galaxies", every being is bipedal due to various peculiarities of the cultural and religious context of the world Bargon 7. Frogs (which are five times the size of the kind we get on Earth and are extremely muscly) are the apex species, with reasonably advanced technology (Bronze Age equivalent).
Given this backdrop, a class of frog warrior priests has risen to prominence and taken control of the central council of Celirion 9. There are various other creatures which we have on Earth. but everything is bipedal. These are normal size and haven't evolved any differently, but I haven't fancied any of these to be good challengers for the frogs.
Which other animals from real life could I adapt to stand on two feet and be a relatively equal challenge to the frogs?