Two scientists in the jungle find a baby brontosaurus. They have to climb up a cliff and negotiate with Tintin-quality "savages" who might even put them in a big pot of water, although it's also possible that I'm thinking of one of those Romancing the Stone movies. Presumably the dinosaur is eventually reunited with its mother, and the bad guy (a scientist who wants to dissect the dinosaur? a poacher?) has a change of heart or falls in mud.