Prehistoric Dinosauriform <i>Asilisaurus</i> (IMAGE) University of Washington Caption Ten million years after the mass extinction, members of the archosaur reptiles -- such as the 10-foot (3 meter) long Asilisaurus pictured -- had more restricted geographic ranges compared to the communities of four-legged animals that existed before the extinction. Credit Marlene Donnelly/Field Museum of Natural History Usage Restrictions Credit required 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.