Sciences in 1854. Leidy identified the bone as a lower jaw, a mistake that was not corrected until English paleontologist Richard Owen reinterpreted it as an upper jaw in 1876. Leidy erected the new genus and species Bathygnathus borealis, which means "northern deep jaw" in Greek as a reference to the height of the jaw and its discovery in Canada. He identified it as belonging to a dinosaur, although he never called Bathygnathus a dinosaur in the paper (Dawson later described it as "a carnivorous reptile... one of that giant reptile aristocracy which constituted the highest animal type in the middle or secondary period of geologic time"). Leidy compared Bathygnathus with Thecodontosaurus from the Triassic red beds of the United Kingdom, one of the first dinosaurs to have been described scientifically. Dawson inferred that Bathygnathus was a fast-moving carnivore, reasoning that its deep skull was similar to the short skulls of fast-moving snakes and unlike the long skulls of slow-moving crocodilians. Local naturalist Francis Bain popularized the image of Bathygnathus as a dinosaur in the late 1800s, describing it as a "deep jawed monster" that could attack prey "with a bound of sixteen or eighteen feet... bearing it to the ground with its great weight, while the powerful claws prevented its escape, and the sabre-armed jaws completed the sanguinary work of destruction." American paleontologist E. C. Case reclassified Bathygnathus as a pelycosaur (a type of "mammal-like reptile") in 1905, noting its similarities with the genus Dimetrodon, a sail-backed synapsid that was discovered in Texas in the 1870s. In their 1940 overview of pelycosaurs, Alfred Romer and Llewellyn Ivor Price suggested that Bathygnathus might be synonymous with Dimetrodon. References Fossils of Canada Paleontology in Prince Edward Island Sphenacodontidae Cisuralian synapsids of North America Fossil taxa described in 1854 Taxa named by Joseph Leidy Paleozoic life of Prince Edward Island Cisuralian genus first appearances Cisuralian genus extinctions