Thanks for the opinions on the vegetation. That stood out as being different from the rest of that steep slope. I think maybe they blew down from the flat area above. Not sure if "tumbleweed" grows on steep slopes or changes color when it's ready to roll. The telephoto viewpoint takes away depth perception, making everything look more flat/2D-ish.
It is a daunting task considering that Mr. Miller may not have worn any colors that contrast with the landscape. The north part of the western plateau has a lot of visibility of the ground and is fast travel, but when I was in the southern part of that area yesterday I was thinking how the vegetation made it difficult to see anything on the ground beyond 25 or 50 feet away. There's also a lot of unsearched rocks in the hills west of the parking lot. It seems that nobody has hiked up to whatever the helicopter pilot may have seen on the southern plateau, and the western ridge hasn't been searched in the upper areas.
People may be underestimating his speed, and he may have had a little more time than originally reported, according to Neil's account. Even Neil may have underestimated his speed. Back in May when I went up the SE drainage, I left the trail near the oasis at about 23 minutes after jogging with a heavy load of water. I think a fast hiker could reach the oasis in a little over half-hour, and maybe he started jogging after catching his breath on the downhill and passing Neil.
The skull was smaller than an adult's fist, larger than a kid's fist I think.
The brown and black stuff seemed like more quantity than what could come out of a 70-lb. mountain lion in a single event, but maybe such an animal is capable of amazing things. I did notice mud underneath other boulders but not the black stuff. So maybe mud + scat/vomit?
Yesterday I found my 3rd decent-sized cave in 4 search trips, not counting the usual spaces between boulders. I think there's a possibility that he took shelter in a cave. In a state of heat exhaustion and near heat-stroke he might not have been thinking about how people would find him. Or he may have thought that if he just recovers for a bit inside the cave, he could walk back and not need any help. A cave certainly helps with heat exposure but doesn't solve the issue of dehydration and risk of kidney failure (not sure how long that takes but read it's more likely with exertion). A cave also muffles sound. A fall in a crevice as mentioned by rosesfromangels is I believe another likely scenario, probably more likely. Muscle cramps from dehydration or low sodium could contribute to a fall.
Look up from under the boulders.
When people say look up from under the boulders, what does that mean? I know there is a risk of hitting your head if you don't look up, especially if wearing a hat with a brim or visor. Or maybe you mean crouching and looking up into a small cave?