Edaphosaurus (IMAGE) Field Museum Caption Edaphosaurus, an early mammal relative that lived around 300 million years ago, which had a more primitive backbone with just three different regions. Credit Field Museum Usage Restrictions Please include credit to Field Museum License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.