Dinosaurs and Pterosaurs

66 million years ago, two closely related groups of reptiles, dinosaurs and pterosaurs, which are scientifically grouped into the clade Ornithodira, are believed to have gone extinct. However, many reports of dinosaur like creatures, Mokele Mbembe, and giant bat like creatures have led some, but not most, cryptozoologists to think dinosaurs and pterosaurs may still be alive.

Pterosaurs

Main article: Pterosaurs and Pterodactyls in Cryptozoology

Dinosaurs

Dinosaurs are prehistoric animals that evolved during The Triassic, and most likely became extinct during the Late Cretaceous, excluding birds. Despite popular belief, no dinosaurs lived in the water or flew, excluding birds, which survive today. (The most well known prehistoric animals that were aquatic are Plesiosaurs, and the most well known prehistoric reptilian flyers are Pterosaurs, which are often mistaken for dinosaurs.) There are two main groups of dinosaurs: Saurichian, or lizard-hipped, and Ornithischian, or bird hipped.  Saurichians include the theropods, which include Tyrannosaurus rex, Velociraptor mongoliensis, and birds; as well as the sauropods, which include Brachiosaurus altithorax and Amargasaurus cazaui. Ornithischian dinosaurs included many types of dinosaur, but no carnivores; only herbivores and omnivores. Some Ornithischians include Corythosaurus casuarius, Triceratops horridus, Pachycephalosaurs wyomingensis, and Stegosaurus armatus. Dinosaurs, excluding birds, are believed to have been driven to extinction during the Late Cretaceous. There are many theories regarding how or why, but the most widely accepted theory is that an asteroid struck the Earth. The extinction may have lasted for thousands of years. The last dinosaurs to have been killed due to this extinction (based on fossil evidence) were the ceratopsians, like Triceratops. However, cryptozoologists have been reporting that dinosaurs may have survived, like large tyrannosaurs, or even sauropods (Mokele Mbembe) which were mostly killed off (in exception to titanosaurs) during the Late Jurassic. Still, the possibility of dinosaurs still living continues, especially in areas where the ecosystem hasn't changed much over the past 66 million years. The remote and dense jungles of the Congo, the world's most unexplored rainforest, are ideal for a living dinosaurs, because its climate is hot and humid and it is lush in vegetation due to its small population of people. This is all very unlikely, however, based on fossil evidence, but one must not rule out the possibility.