Dimorphodon was a small pterosaur that lived during the Early Jurassic, about 195 to 190 million years ago. Although it is often grouped with dinosaurs in popular displays, it was not a dinosaur, but a flying reptile closely related to them. Its large head, long tail, and leathery wings make it an important example of early pterosaur body design.
Studying Dimorphodon helps paleontologists understand how vertebrate flight evolved before birds appeared.
Dimorphodon is named for its two different kinds of teeth, with long pointed teeth near the front of the jaws and shorter teeth farther back. Its wings were formed by skin membranes stretched mainly along an extremely long fourth finger, not by feathers. Fossils from places such as Lyme Regis in England show that it lived near coastal environments where it may have eaten fish, insects, or small animals.
Its body plan suggests a capable but probably not highly specialized flyer compared with later pterosaurs.
Key Facts
- Dimorphodon lived in the Early Jurassic Period, about 195 to 190 million years ago.
- Dimorphodon was a pterosaur, not a dinosaur, because pterosaurs belong to a separate flying reptile group.
- Its name means two-form tooth, referring to two distinct tooth types in its jaws.
- Wingspan was about 1.4 m, while body length was roughly 1 m including the long tail.
- Pterosaur wings were supported by an elongated fourth finger and a membrane of skin.
- Speed = distance/time can be used to estimate flight speed from fossil-inspired motion models.
Vocabulary
- Pterosaur
- A flying reptile from the Mesozoic Era with wings made of skin membranes supported by an elongated finger.
- Dimorphism
- The presence of two different forms of a structure, such as the two tooth types seen in Dimorphodon.
- Wing membrane
- A sheet of skin and connective tissue that formed the flight surface of a pterosaur wing.
- Fossil
- Preserved evidence of ancient life, such as bones, teeth, footprints, or impressions in rock.
- Jurassic Period
- A period of the Mesozoic Era from about 201 to 145 million years ago when dinosaurs and pterosaurs were widespread.
Common Mistakes to Avoid
- Calling Dimorphodon a dinosaur is wrong because it was a pterosaur, a different branch of reptiles that evolved powered flight.
- Drawing its wings like bird wings is wrong because Dimorphodon had skin membranes supported by a long fourth finger rather than feathered arms.
- Assuming the large skull made it too heavy to fly is wrong because fossil anatomy suggests its bones were lightweight and adapted for flight.
- Treating all pterosaurs as the same is wrong because early forms like Dimorphodon had long tails and different proportions from many later short-tailed pterosaurs.
Practice Questions
- 1 A Dimorphodon model has a wingspan of 1.4 m. If a museum builds a model at 2 times life size, what is the model's wingspan?
- 2 A pterosaur glides 36 m in 4 s during a simulation. Using speed = distance/time, what is its average speed?
- 3 Dimorphodon had a large skull, two tooth types, a long tail, and membranous wings. Explain how at least two of these traits can give clues about its diet, movement, or evolutionary relationships.