Great Valley entrance and their number is one of great mysteries for me.

Judging by movies, there're couple huge entrances, and endless amount of small or hidden entrances. Some of them are small so only small leafeaters/eggstealers/sharpteeth or children can pass through, if they will be able to find the path in the first place and bypass various obstacles...

The main question for me is how these passes are guarded from sharpteeth.

I would guess that the smaller passages are difficult to find and generally remain unguarded. This might explain why egg-thieves and other small theropods are able to get in, albeit in small numbers. I have not seen all the movies, and am mostly a LBT1 purist. But nonetheless, I like to think there is a bigger entrance, large enough to fit a longneck, that leads to a winding cave gradually slopping downward through a mountain and widening at the end, opening up into the valley and that is the entrance most dinosaurs use. I also think it’s the one all the carnivores are looking for. I’m thinking that entryway would be located on the side of a mountain with a pathway winding its way down through a small mountain range with the mountains themselves providing total cover from sight. As for protection, I’d say the cave entrance on the mountain is guarded by a series of ankylosaurs working in shifts.