Allow me to answer this question by quoting a recent post of mine in which I discussed
Troodon's diet:
Anyway, my theory is that the filmmakers used Troodon as the basis for the rainbow faces, but made them less “sharptooth-like” by removing the sickle claws (which weren’t as prominent as those of their relatives, the dromaeosaurs, to begin with) and keeping the teeth non-visible most of the time. (There is at least one shot in which you can see a set of pointed teeth in the female rainbow face’s mouth.) Also, while Troodon is generally thought of as a carnivore, its teeth are serrated in a similar way to those of plant-eating dinosaurs, so it may have included some plant matter in its diet, so it’s not altogether implausible that they could coexist with leafeating dinosaurs in the LBT series.
By the way, there's never any indication given that the hidden runner is a
Troodon. (As I indicated in my post, I believe the rainbow faces to be based on
Troodon.) Although its eyes, nocturnal habits, and overall body shape are similar to, it appears to have no teeth, and only two digits on both its hands and feet. (No non-avian dinosaur is known to have two-toed feet.) Then again, allosaurs, raptors, and even domeheads in LBT have been depicted with two fingers (and, in the domeheads' case, two toes as well), so perhaps we can't rely on the number of digits. It could be based off an alverezsauróa family of fast-running, birdlike dinosaurs whose later members evolved reduced forelimbsóor it could be an entirely made-up dinosaur.
One more thing, JBJB1029: I'm not going to write your fanfiction(s) for you, or give my opinion on every single idea you come up with, but if you had any questions specifically about dinosaurs and other prehistoric life, you can just ask me about it, rather than continually posting new threads in which you ask a single question of the entire forum. (Frankly, I think a lot of people are getting tired of it.)