Spinos aren’t necessarily actually better than a rex for a few reasons, and theres some stuff i’ve been reading here that is just flat out wrong. Rexes and spinos are almost equals, with rexes being a bit more combat focused and spinos being better at everything else

Spinos do outdamage a rex IF they stand on 2 legs, tamed unridded spinos will NOT do this. Meaning unless it is being ridden a rex will outdamage a spino in dps

A spino does have greater knockback than a rex, good enough to juggle alot of enemies die to the fast attack speed, rexes can do the same thing but it’s harder and it will not work against creatures too fast.

Spinos get the hydration buff which increases health regen slightly (barely noticeable) damage, and speed. It gets this buff if it touches even a tiny puddle of water. It does not have to go into deep water to get the buff

Rexes do have better health than spinos (and better dps if the spino is on all fours or unridden). Rexes are usually better for bossfights unless theres water in the arena.

Rexes are in general much easier to tame. Spinos are annoyingly hard to trap unless it is a pre built trap. Even then spinos havea much easier time climbing over walls than rexes, the also move much faster and have even less attention span

NOTE: Rexes do not have short attention spans UNLESS you are on a flyer. If you are on a flyer that is landed or on a land mount or even on foot it will follow you just fine. Spinos however would much rather target fish than you, and due to their preference of water leading them away may be difficult as it might lose interest if taken too far from the water, or focus on fish if any are nearby

Standing on a rock can work however once they start running they are fast with the hydration buff, and it is possible to knock them out in the water, meaning they will drown. I highly recommend using a pre built large box trap at least 3 walls high. Alternatively if you dont want to pre build a trap you can use a large beartrap, and a few stone gateways. Place down the beartrap, lead the spino to the trap, and place the gates around him and tranq at your leisure. I recommend the first option however

Another thing is that once knocked out they prefer fish to meat, they also prefer raw prime fish meat to raw mutton or prime meat. This may may it harder or easier depending on your location and environment. On valguero and ragnarok it is easy to get mutton if you have a flyer to quickly bring it back to a tame before it spoils. I usually do this with any large carnivores to save on kibble. But if you already have a capable water mount or have nearby sabertooth salmon available then this will be rather easy as long as you keep its torpor up. Kibble of course also works as always if you have access to it.

Thats about it just a few more side notes

Tamed rexes will not i initiate a roar when entering combat. Only wild rexes do.

Spinos arent nearly as maneuverable as other aquatic creatures in the water, and you may find yourself getting outmaneuvered and bitten in the back alot. Spinos are much better for rivers and lakes than open ocean.

Theres very good reason why rexes are so often used in boss fights rather than spinos. Unless theres water in the arena rexes are almost always a better choice, if not therizinos.

I am not a rex fanboy, i much prefer spinos myself. But i cant stand blatantly wrong information being posted here. Dont get me wrong a spino will absolutely body a rex if it stands up, but because tamed spinos dont do that unless ridden rexes will out damage them, ontop of that rexes absolutely have more health.

Spinos suit a much different role in my opinion, very equal as a battle mount, worse as an army. Far superior as a travel mount. A good high level spino will kill everything outside an alpha rex, or a giga. You may have a hard time against alpha wyverns or high level alpha carnos.

It should also be noted that alpha mosas and alpha squids will, obviously prove to you that they are the kings of the deep by ripping amd tearing your spino a new a**hole.

I’m going to start breeding spinos soon to create a really good traveling tame to take me anywhere. And in my opinion thats what they’re for, traveling while being good protection against anything a same level rex can kill.