These must be relatively new trails. I believe that park of the park was only acquired a few years ago. Looks like some great additions to the park's trails!
Thanks for looking and voting,
I only started looking at maps of Palo Duro about 6 months ago. Rock Garden and Rylander Trails appear on the map (the Rim Trail that I followed does not). Rock Garden was well signed and even had mile markers every 0.1 miles.