Imho perfect casting on lonesome Dove, both Duvall and Jones can actually ride a horse. They were well mounted but the grey horse they called the hell bitch was actually a gelding. I thought Diane Lane done a good job.
The story is that Duvall did not know head from tail on a horse when he went to Hollywood.
But, as the majority of films in those days were westerns, Duvall figured that more roles would become available if he could ride a horse. So he got professional training.
And the rest is history, as the saying goes.
