<I>Cronopio dentiacutus</I> Fossil Photos (IMAGE) University of Louisville Caption Paleontologist Guillermo Rougier, Ph.D., professor of anatomical sciences and neurobiology at the University of Louisville, and his team have reported their discovery of two skulls from the first known mammal of the early Late Cretaceous period of South America. The new critter, named Cronopio dentiacutus by the paleontologists, is a dryolestoid, an extinct group distantly related to today's marsupials and placentals. Credit University of Louisville Usage Restrictions EMBARGOED to 2 p.m., Wednesday, Nov. 2, 2011 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.