Stegosaurus (IMAGE) Princeton University Caption The discovery of a single anatomical difference between males and females in the species <i>Stegosaurus mjosi</i> provides some of the most conclusive evidence that some dinosaurs looked different based on sex, according to new Princeton University research. The species had two varieties of plates -- short and wide, and tall and narrow. Lacking fossil evidence of which sex had which plate type, Saitta supposed that males (top) had the wide plates, which likely served as Credit Photo by Evan Saitta, University of Bristol Usage Restrictions None 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.