You may ask, how many baby rexs will i need for the entire taming process? Well, its 1 for 100% trust, but your most likely not to complete the entire taming process in one go, so here’s a list: (i still recommend extra rexs incase there is a lack of creatures in your area)

Lvl 1-40: 1 or 2

Lvl 40-80: 2-3

Lvl 80-150: 2-5

It really depends on how many and what creatures are around, but its never guaranteed for a one and done, so good luck and happy taming.