I have this memory of a TV cartoon show with a bunch of dinosaurs (5, I guess), each with different colors and from different species. One was a triceratops, another was a diplodocus, but they were all the same size. They were really cartoonish.
There were no humans, and the stories happened way before our time, hence they were discovering many things.
I remember seeing that show as a child in France, so between 1995 and 2005.
One of the episodes I remember is when they see a rainbow for the first time and they decide to build a raft to see its beginning. The whole episode was them rowing, imagining what it could be and giving it a name. They argue between "Rainbow" ("Arc-en-ciel" in French) and "Color Acre" ("Arpent à couleurs" in French, not sure at all for English). Finally, they understand that they'll never get the rainbow and go back where they came from.
Of course, this is NOT The Land Before Time, neither Denver.