Kyouryuu Densetsu (恐竜伝説 - "Dinosaur Legend") is a NES/Famicom game that was being developed by HAL Laboratory but ended up cancelled/unreleased.
It would have been an RPG set in a world populated by dinosaurs, that the hero should save, having his own dinosaur who would evolve and become more powerful.
There is very little information regarding this cancelled title otherwise. A small blurry screenshot is the only visual evidence left of it.
http://beraboman.fc2web.com/mihatubai.htm A list of cancelled games in Japanese.