Overthinking "Dinosaur Train," part 1

A staple of Una's television viewing, the PBS cartoon Dinosaur Train (by the Jim Henson Co) annoyed me at first, but it has grown on me and now I rather like it. It won me over partly with little things, like the fact that many of the dinosaur species have accents and other personality quirks based on where they were discovered (the Iguanadon likes to do Monty Python silly walks), partly with enjoyable songs, and partly with good character development. But there are still a few nagging questions, from a world-building perspective, that I can't help wondering about.

Most obvious is the question: whence the time-travel technology? The Troodons like to brag about how smart they are, but I don't see that they've come up with many non-train-related inventions. One suspects that someone else supplied them with time-travel capability. "Aliens" might be the obvious answer, although the question then becomes "why would the aliens bother doing that?" I have another theory, though. Whom do we know of who (a) knows of time travel, (b) has a family that includes two young children, who very commonly love anything to do with dinosaurs, (c) might do any nutty-seeming thing on a whim, and (d) was last seen operating a time machine in the shape of a (flying) train?

Doc Brown, of course.

Arguing against this hypothesis is Doc Brown's usually scrupulous concern about messing up the space-time continuum. Giving dinosaurs technology would seem to be a rather large disruption. But this actually dovetails with another nagging question: why does the Dinosaur Train only travel within the Mesozoic Era (the age of dinosaurs)? Perhaps Doc Brown rationalized that as long as the dinosaurs could only travel within their own era, and not use the train to escape their ultimate fate, all would be well. Presumably he made sure to keep his explanations to the Troodons limited to practical operating instructions, without getting into actual time-travel theory. As far as we can tell, this seems to have worked.