Ophtahalmosaurus was a species that lived in late Jurrasic roughly between 165 and 150 million years ago but vanished at the beginning of the cretaceous. The species was definitely not around in the Triassic! Apart from the BBC documentary there are many webpages and books which will confirm this.
The same goes for Stegosaurus (which also lived at the end of Jurrasic and vanished roughly 145 million years ago). Apatosaurus and Diplodocus both fall in a similar period of time. I will not argue the possibility that a few representatives of this species probably lived at the beginning of cretaceous (they didn't vanish from one day to the other, so I have no problem giving them some thousand or even a million years more). Triceratops however is a late cretaceous species (about 70 to 65 million years ago) and so are almost all hadrosaurs (all these Duckbills). There is no realistic chance of the species in the land before time to have met in reality. Yet as I said, LBT is a story, of a genre in which scientific accuracy is not really required.
As for the Triassic species, I mentioned them in an earlier post. Mussauruses and Thecodontosauruses are both Triassic species which may well represent the "Tinysaurs".
Whatever your friend Kyle may have called that species in the original movie, it WAS a Dimetrodon. If he called it something with "s" he may have thought it to be a Spinosaurus (a cretaceous species which had a "sail" on it's back similar to that of Dimetrodon). However, apart from the sail there is no similarity between the two species and you can tell the creature in the movie is a Dimetrodon from the limited size and its being a Quadruped.
