Final Fantasy IX has some of the best dungeons in the series. However, Fossil Roo isn't one of them.
Fossil Roo is tied with the battle system for being the biggest piece of proof that Squaresoft had no respect for the time of the player. This is a dungeon that consists of
the party being ferried around by giant monsters, which requires you to watch the same cutscenes over and over again.
It is also a dungeon that has a lot of back-tracking, especially if you are playing the game for the first time.
It's possible to complete Fossil Roo relatively quickly if you know exactly what you are doing, but most players will be stuck watching the same cutscenes over and over again in an attempt to solve the puzzles.