Acanthotelson stimpsoni (Shrimp) - Mazon Creek FossilMarine Estuarine Shrimp: Fossil shrimp were first reported from the Mazon Creek area around 1860, but prior to the opening of Pit 11 in the mid 1950s, the diversity was remarkably small. Now, they are divided into robust non marine and marine estuarine groups. These fossil arthropods are preserved in full body detail or as exoskeleton molts.