Oldest Grass Fossil (IMAGE) Oregon State University Caption This grass spikelet from the middle Cretaceous is about 100 million years old, preserved in amber as the earliest fossil ever found of the evolution of grass, and is covered on its tip by the parasite ergot. Credit (Photo courtesy of Oregon State University) 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.