How high can dinosaurs lift their feet

I am currently trying to create a fenced area to keep dinosaurs in. I've noticed that brontosaurus and t-rex' seem to be capable of going over my one stone wall heigh fence.

I've also noticed that due to the irregular landscape, my wall is easier to traverse at some locations.

How high does a fence have to be to prevent all dinosaurs from passing?
Which dinosaurs are capable of traversing a one unit high wall?

I've been testing this myself, and have come to the following rough estimate.
This is based on the sizes of creatures as defined by the size of their feces.

1. Small class dinosaurs are incapable of traversing one height walls
2. Medium class dinosaurs are incapable of traversing two height walls
3. Large class dinosaurs are incapable of traversing three height walls

It would seem however that the surrounding ground is important when trying to keep your base from being walked into.
Small hills near your base might enable medium size dinosaurs such as a t-rex to step over walls of two units high.

While I've seen a wild t-rex traverse a two height wall from an adjacent hill (to feast on our philo farm), I was unable to reproduce it on a tamed t-rex, so this might not be wholly conclusive and more in the realms of glitched pathing.