ATMachine said:

In his 1977 story conferences with Leigh Brackett, GL said something about wanting to create a fantasy film where all the knights rode around on giant lizards.

Then he made Willow and completely failed to pick up on that idea.

(Or maybe he just realized how hard it would be, thanks to all the stop-motion Tauntauns and AT-ATs used in ESB.)

Pity, in my view. I'd really like to see on screen a fantasy world where heroes ride on sauruses in the vasty desert, Lawrence of Arabia style.

Actually he did make this movie, it's just that the final production design really hid the fact that Tauntauns were originally conceived as snow lizards. When I saw that description of them, I thought the writer was on drugs--they were clearly mammals of some sort for goodness sake, but then I saw it elsewhere, so, uhh... vasty ice fields, anyone?