Initial analysis clearly indicated the specimen was a plesiosauroid—a family of long-necked marine reptiles that swam Earth’s ancient oceans. Researchers soon transferred it to the Stuttgart State Museum of Natural History, but the creature never received a thorough examination. After nearly 50 years of storage, paleontologists were finally able to carve out time for a thorough evaluation of the mystery. The remarkable skeleton measures nearly 10.5 feet long with a 4.1 feet neck composed of at least 43 vertebrae. P. longicollum is now the sixth plesiosaur species discovered at the Posidonia Shale in Holzmaden—including representatives from all three major plesiosaur lineages.