Neither primeval nor weretouched master received any options, improvements, or extensions in any supplements beyond those in which they were originally printed. Their particular forms of shape-shifting are unique and not expanded upon by other classes or feats. They do not even qualify for master of many forms, the usual go-to solution to wanting to turn into something you usually can’t.
Weretouched master can only turn into the six animals listed. They never published additional animals for that list, much less added dinosaurs to it (not even when they published saurian shifters). The weretouched master is what you see in Eberron Campaign Setting and nothing more.
Primeval gets marginally closer, since primeval form “functions similarly to the druid’s wild shape,” but similar is probably not good enough to actually count as wild shape for prerequisites. That means options that would improve wild shape, and might work here, won’t work for the primeval. Moreover, the primeval’s inability to select new forms ever means that even if it did count as wild shape, you wouldn’t be able to pick a larger dinosaur because in order to qualify you have to actually have the class feature, but once you have it you’re locked in to your initial choice.
Master of many forms from Complete Adventurer is still your closest bet. Maybe your DM lets you use it on primeval form, and lets you use new forms as if primeval form was wild shape. But primeval form is still badly limited in uses per day, and requires taking most of your feats and setting them on fire (all three of those feats are awful).
You would be vastly better served by just being a druid, and taking master of many forms. It, too, requires a couple of terrible feats, but you get much more out of it. You will have more uses per day, far more options, and so on. If you really want to avoid druid spellcasting (even though it’s excellent), you can get wild shape as a monk (Dragon 324) or ranger, too. Or if you want to have a greater emphasis on being a shifter, shifter druids can use the quite-good moonspeaker prestige class from Races of Eberron (though honestly I think straight druid is probably better, but then, straight druid is better than most things). Also, kind of random, but the bloodclaw master from Tome of Battle has special features for shifters (though honestly they’re not really that good).