During the Paleozoic era, which lasted from 541 to 252 million years ago, there were a variety of animals that existed, including:

• Trilobites
• Brachiopods
• Eurypterids
• Ammonoids
• Crinoids
• Blastoids
• Graptolites
• Jawless Fish
• Cartilaginous Fish
• Bony Fish
• Amphibians (early tetrapods)
• Reptiles (toward the end of the era)