National Geographic Live Speaker Series, Spinosaurus: Lost Giant of the Cretaceous. Paleontologist Nizar Ibrahim will share his exploration and ultimate reconstruction of a full skeletal model of Spinosaurus, the largest predatory dinosaur yet discovered. With dramatic video recreating the lost world of the Cretaceous Era Sahara, Dr. Ibrahim will weave the spellbinding tale of Spinosaurus’ discovery, loss, and rediscovery, and explain what makes this ancient monster unique. Photo: Mark Thiessen