Technically, This is midgame elona: All the pets (Catsister, Trex, and the black angel,) are capable of reaching the same ~200 speed level (With the angel being slowest, and only remotely close in a self buffed state that uses a significant chunk of stamina, hence, her struggling to keep up with the brainwashed Trex.)
Mechanically, Nukes are used to farm midgame-unique items, as they usually belong to people who are hard to kill in conventional mechanics.
The T-Rex is just among the best vanilla mounts, regardless (And riding reduces your weight loads effect on your movement, IE, allowing you to carry a nuke with less death.)
This is a plethora of game mechanics in one easy to view image.