The First Dinosaur Fossil Scientifically Described
The first dinosaur to be described scientifically was Megalosaurus. This genus was named in 1824, by William Buckland; Gideon Mantell (not Ferdinand August von Ritgen) assigned the scientific type species name, Megalosaurus bucklandii. Buckland (1784-1856) was a British fossil hunter and clergyman who discovered collected fossils. (Note: the first dinosaur found was Iguanodon, but it was named and described later than Megalodon.)
Megalosaurus was the first dinosaur ever described scientifically and first theropod dinosaur discovered (this is all in hindsight, because the dinosaurs had not yet been recognized as a separate taxonomic group - the word dinosaur hadn't even been invented yet).
The first dinosaur models (life size and made of concrete) were made by Benjamin Waterhouse Hawkins of England in 1854. The first dinosaur used for amusement was a life-size model of an Iguanodon (also made by Hawkins) that was used to house a dinner party for scientists (including Richard Owen) at a major exhibition. The invitations to the party were sent on fake pterodactyl wings. The party took place in London, England, in 1854