Kodai Ouja Kyouryuu King

Max is obsessed with dinosaurs. He knows his Tapejara from his Pteranodon and can find fossils better than a trained paleontologist. When he discovers a stone tablet that transports him to the age of dinosaurs, it's a dream come true--until it becomes a nightmare. An evil genius named Dr. Z has enslaved the dinosaurs so he can use their hidden powers to take over the world! Now Max has to defeat Dr. Z and his Alpha Gang to save the ancient beasts and life as we know it.

(Source: Viz Media)