World's Best Preserved Mosasaur Fossil (IMAGE) Natural History Museum of Los Angeles County Caption The Natural History Museum of Los Angeles County's mosasaur fossil contains four slabs, which make up a virtually complete, 20-foot specimen. Pictured here is the skull portion of the specimen. Credit Courtesy of the Dinosaur Institute, NHM 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.