Skull of Sphenacodon (IMAGE) University of Bristol Caption This is a skull of a Sphenacodon from New Mexico, one of the fossils used in the current study. Credit Spencer Lucas, New Mexico Museum of Natural History Usage Restrictions This image is for single use only to illustrate this press release and is not to be archived. Please credit Spencer Lucas, New Mexico Museum of Natural History 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.