Foramen Magnum Evolution (IMAGE) University of Texas at Austin Caption Comparison of the positioning of the foramen magnum in a bipedal springhare (left) and its closest quadrupedal relative, the scaly-tailed squirrel (right). Credit Image from Russo and Kirk, Journal of Human Evolution Usage Restrictions Please contact Russo and Kirk for image permissions. 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.