Ceratopsian at K-T Boundary (IMAGE) Yale University Caption Yale graduate student Stephen Chester discovered the last known dinosaur before the catastrophic meteor impact 65 million years ago. Credit Tim Webster Usage Restrictions With credit. 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.