We're dealing with larger than mountain lion scale beasties here. Fun fact about hippos: they can't jump. Like at all, unless they're submerged and can use the buoyancy of the water. The same is true of just about any modern tetrapod within that size range. If you're a tetrapod the size of a mountain lion or even a bengal tiger, you can still have speed, agility, and the ability to spring, pounce, and grapple with the forepaws. At T. rex scales, the square-cube law has something to say about that.