- countless rattlesnakes, some light-colored, some darker; most slither off the trail, but occasionally they coil up and stand their ground, and you must go around them
- a gopher snake
- a couple dark snakes that move extremely fast
- a thin green snake
- mule deer
- rabbits or hares, squirrels, gophers, chipmunks
- dozens of horned lizards
- myriad other lizards, some of them quite exotic
- possibly, the side of a mountain lion -- it was a large tan shape that moved out of sight quickly and silently, and I could have been seeing things
- tarantulas; one had been stung by a wasp and was immobile, the other was lurking in its den 1 foot from my groundcloth waiting for insects (I fed it some)
- a dead bobcat (roadkill)
- coyotes; did not see them, but heard their wailing
- countless bird species from hummingbirds to hawks
Riled-up rattlesnake; had to go around it: http://www.youtube.com/watch?v=gp2YDNnqitk
Rattlesnake moving off trail: http://www.youtube.com/watch?v=ovEDftFqmHg
Photos
Horned lizard. The coloring of these things varies widely.
Is this lizard surveying his dominion or merely sunbathing? Either way, he appears highly self-content.
Rattler poised for a strike. Nature's way of posting a "Detour" sign.
Tarantulas usually lurk in their holes and rarely come outside.
Male lizards overcome by the "mentality of scarcity." 
Is this a gecko?
Probably a gopher snake.
Chickens huddling together to preserve warmth.
Homo sapiens after some successful hunting and gathering.
