In Valguero they spawn west of small Islands (starter point for noobs). They got attracted by any dino, and a fleeing phiomias or parasaur will eventually get it into water... Make sure to enclose all you base or you might get D-Day wiped
If you are having a hard time finding spino's in their respective spawn zones (especially Ragnarok), kill all the fish in that area. They share the same spawn capacity and can be out spawned by coles! ( up vote so Rag players know!!!)
As far as I know, only 3 wild carnivores will aggro onto the sight of your spino, other Spinos, Rexes, and Gigas. You can probably outfight other spinos, outrun rexes, or outfight lower level ones, and outrun gigas. Very useful.