Fossil shell (IMAGE) Smithsonian Tropical Research Institute Caption The researchers found preserved bone cells in the carapace, which exhibited structures like the nucleus of a cell, where DNA traces were found. Credit Dr. Edwin Cadena, Universidad del Rosario and STRI Usage Restrictions Credit must be given to the creator. Only noncommercial uses of the work are permitted. License CC BY-NC 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.