Dinosaur Sizes (image) University of Oxford Caption An Oxford University-led team studied how dinosaurs evolved into a huge range of shapes and sizes over 170 million years. Shrinking their bodies may have helped the group that became birds to continue exploiting new ecological niches throughout their evolution. Credit Julius Csotonyi Usage Restrictions To illustrate this story 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.