Dimorphodonmacronyx

Overview: While dinosaurs were diversifying on land in the Early Jurassic, pterosaurs were cementing their rulership of the skies. One of these Early Jurassic dragons was Dimorphodon, a medium-sized pterosaur with a big head and unique heterodont (different shaped) teeth. It was discovered in the early 19th Century by Mary Anning on England’s “Jurassic Coast”, making it one of the historically earliest pterosaurs found, as well as one of the geologically oldest pterosaurs known from good material.

Discovery: Dimorphodon was discovered in 1828 in the coastal exposures of the Blue Lias Formation on the “Jurassic Coast” near Lyme Regis, England by the legendary fossil collector Mary Anning. The holotype (original) specimen was acquired by William Buckland who named it as a new species of Pterodactylus, Pterodactylus macronyx, macronyx being derived from Greek “makros”, meaning "large" and “onyx” meaning, "claw", in reference to its large hand claws. In 1858, Richard Owen (who coined the word dinosaur in 1841), after the discovery of additional specimens, correctly recognized that P. macronyx was not actually Pterodactylus, and gave it its own genus, Dimorphodon, a description of which he provided in 1859. Dimorphodon means “two-form tooth” from Greek “di meaning "two", morphe”, meaning "shape", and “odon”, meaning "tooth", referring to its two distinct tooth shapes. The holotype, NHMUK PV R 1034, was officially designated as the holotype by Owen in 1874. Dimorphodon is one of the earliest pterosaurs known from good material. Most Triassic pterosaurs, with the notable exception of Caelestiventus, which is known from a complete skull and wing, are known from highly fragmentary material, sometimes just individual bones. This makes the Early Jurassic Dimorphodon an important animal for understanding the early evolution of pterosaurs.

Evolution and Description: Dimorphodon was a type of pterosaur, flying reptiles closely related to dinosaurs, but not dinosaurs themselves. These creatures had somewhat bat-like membranous wings supported by the arm and a hyper-elongated finger. Dimorphodon appeared in the Early Jurassic and was a rather basal (“primitive”) member of the Pterosauria. Like other early pterosaurs, it had a toothy mouth and a long tail. Dimorphodon was a medium-sized pterosaur, about 1 meter (3.3 ft) long with a wingspan of 1.45 meters (4.6 ft), a far cry from the much larger pterosaurs of the Cretaceous, but a decent size for a Jurassic pterosaur. As implied by its species name, it had proportionally large claws on its hands, which would have helped it climb through the trees. It had a large, boxy skull which measured about 23 centimeters (9.1 in), the snout of which sort of resembled an elongated version of a puffin’s beak, but with teeth. The skull was extremely lightly built, with large openings called fenestrae to reduce weight. Despite this, the skull was still structurally strong. Weight-reducing features like hollow bones, bird-like pneumatic vertebrae, and large skull fenestrae were common throughout the Pterosauria and were adaptations for flight (though the pneumaticity of pterosaur vertebrae, like that seen in dinosaurs, probably evolved originally as part of an avian-style respiratory system). Somewhat uncommon for reptiles, Dimorphodon had distinct heterodont dentition, i.e. it had distinct different kinds of teeth. In the front of the upper jaw were four to five pairs of large fang-like teeth, matched by five pairs of fang-like teeth at the front of the lower jaw, while the teeth in the back of the jaws were small, flat, pointed teeth. Dimorphodon had proportionally short wings for its size, meaning it probably only flew in short bursts.

Ecology: Dimorphodon probably lived in a coastal region and may have had a varied diet. For a long time, it has been portrayed as a fish-eater, but this is not supported by biomechanical studies. William Buckland originally hypothesized it to be an insectivore, and this may indeed be partially correct, though dental microwear analysis suggests that it was primarily eating small vertebrate prey.

Extinction and Legacy: The extinction of Dimorphodon is not documented, but it probably went extinct as newer more derived pterosaurs evolved to take its place. Now Dimorphodon can be seen in various museums, including the Natural History Museum in London, England, the Rainbow Forest Museum in Petrified Forest National Park, Arizona, USA, and the Rocky Mountain Dinosaur Resource Center in Woodland Park, Colorado, USA. Dimorphodon has appeared in various media, including the Jurassic World movies. However, its portrayal in these films, particularly Jurassic World (2015), is inaccurate, overinflating their size and depicting them as far more powerful and aggressive than they would have been in real life.