Skull face (IMAGE) University of Texas at Austin Caption Shown is a close-up CT scan of the skull of a Zygaspis quadrifron specimen. Credit Photo courtesy of the Jackson School of Geosciences CT lab Usage Restrictions Include photo credit License Original 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.