Prehistoric animale ~ Their actions

While some prehistoric animals died out completely, becoming extinct, the descendants of others are still living on Earth. The best-known extinct animals are dinosaurs, huge animals that disappeared about 65 million years ago. Sponges, corals, sea stars (starfish), snails, and clams—all familiar creatures today—can be traced back 500 million years or more. Spiders originated almost 400 million years ago. Insects and sharks also have long histories.