I figured as much, when a charcter doesn't leave the great valley it's a bit silly to just stop talking about them, expecially when they get involved with such an important character as Mr Threehorn. I mean, what happened with Hyp and the other two guys? I guess since they were older they didn't hang out that much with the gang of five, still the way they just disappeared makes no sence. LBT is made for kid but they're not idiots!
As for the topic itself, I didn't know you guys didn't spot that female threehorn in the background =p
Another charcter that eventhough is in many movies never said anything is Ducky's father. What's up with that?
As for T-Rex's being loners and not keeping their mates, I disagree with that theory, I believe that much like howels and eagles, carnivorous dinosaurs made pacts to mate for life, perhaps not raptors since they developed packs so they could have some sort of hierachy, or some sort of family, with children going away every once in a while. I believe that T-Rex's were caring parents that took care of their children together untill they were old enough to leave the "nest".