How about a stamp set of fossils. It can be two sets, one with dinosaurs and the other with non-dinosaur creatures.
So, dinosaur fossils can be T-Rex, Brachiosaurus, Triceratops, Stegosaurus, Pteranodon and Plesiosaurs, although Pteranodon and Plesiosaurs are not formally categorized as dinosaurs
Non-dinosaur fossils can be Trilobites, Ammonoids, Meganeura, sea scorpions, Charnias and Anomalocaris