The Two-Form Tooth

Dimorphodon (meaning “Two-Form Tooth”) was not technically a dinosaur, but a pterosaur — a flying reptile that lived alongside the dinosaurs. It lived long before its movie costars, back in the Early Jurassic period, approximately 195 million years ago. It is instantly recognizable by its oversized, boxy head, which makes up a surprisingly huge portion of its total body length and gives it one of the most distinctive silhouettes of any prehistoric creature.

Despite its small size — only about 1 meter (3.3 feet) long with a wingspan of 1.45 meters (4.75 feet) — Dimorphodon was a fascinating and unusual animal that tells us a great deal about the early evolution of pterosaurs.

Physical Characteristics

Two Types of Teeth

Its name comes from its rare dental arrangement, which was highly unusual among reptiles. Most reptiles have uniform teeth (a condition called homodonty), but Dimorphodon had two distinctly different types (heterodonty):

1. Front Teeth: Long, fang-like teeth at the front of the jaw for grasping prey — likely fish or large insects. These were the largest teeth and were spaced apart, perfect for snatching small, slippery animals.
2. Back Teeth: Rows of smaller, flatter teeth behind the fangs for processing food before swallowing. These are unusual for pterosaurs and suggest a more complex diet than simple fish-eating.

This two-tooth system is remarkably similar to what we see in some modern mammals — think of how you have different types of teeth for different functions. For a reptile living 195 million years ago, this was a remarkably sophisticated dental arrangement.

The Enormous Head

Dimorphodon’s head was disproportionately large — about 23 cm (9 inches) long on a body of only about 1 meter. This gave it a somewhat comical, top-heavy appearance that has puzzled scientists for generations.

However, the skull was remarkably lightweight. Large openings (fenestrae) in the skull reduced its weight dramatically while maintaining structural strength — like an architectural truss bridge. The skull was essentially a framework of thin bone struts surrounding large, weight-saving openings. Despite its size, the skull may have weighed only a few hundred grams.

A Clumsy Flyer?

Scientists have long debated Dimorphodon’s flying ability. Its wings were relatively short compared to later pterosaurs like Pteranodon, and its large head would have affected its aerodynamics. The current scientific consensus is that Dimorphodon was not a graceful, soaring flyer. Instead, it was likely a “clutter flyer” — adapted for:

• Short, rapid flights between trees, cliffs, or other perches
• Maneuvering through dense vegetation rather than soaring over open water
• Powered, flapping flight rather than gliding on thermals
• Quick takeoffs to escape ground predators

Think of it as the pterosaur equivalent of a modern pheasant or quail — capable of flight but preferring to stay close to cover and making short, explosive flights when needed.

Walking on Land

Unlike many later pterosaurs that were awkward on the ground, Dimorphodon appears to have been a capable terrestrial animal:

• Strong hind legs with sharp claws, suggesting it could walk and run effectively
• Possible bipedal locomotion — some scientists believe it could run on two legs like a small dinosaur
• Climbing ability — its clawed hands and feet suggest it may have been an excellent climber, scaling cliffs and trees
• A long, stiffened tail that may have helped with balance during ground movement

This ground capability would have been important for an animal that hunted insects and small vertebrates in coastal and forest environments.

Habitat and Behavior

Coastal Cliff Dweller

Dimorphodon fossils have been found primarily in the Lias formation of Dorset, England — rocks that formed along a tropical coastline during the Early Jurassic. The environment would have been:

• Warm and tropical — southern England was near the equator during the Jurassic
• Coastal cliffs overlooking shallow seas
• Rich in marine life — fish, ammonites, and marine reptiles like Ichthyosaurus swam offshore
• Abundant insects — the warm climate supported large insect populations

Dimorphodon likely nested on coastal cliffs (like modern puffins and gannets) and hunted both along the shoreline and inland. Its clawed feet suggest it roosted on cliff faces and in trees, launching into short flights to catch prey.

Diet

Based on its tooth structure and habitat, Dimorphodon likely ate:

• Large insects — beetles, dragonflies, and other invertebrates
• Small fish — caught during low, swooping flights over shallow water
• Small vertebrates — lizards, frogs, and possibly small mammals
• Possibly carrion — scavenging on washed-up marine animals along the shoreline

Social Behavior

Multiple Dimorphodon specimens have been found together, suggesting they may have lived in colonies — similar to modern seabirds. Colonial living would have provided protection from predators and easy access to shared nesting sites on clifftops.

Discovery and History

Mary Anning’s Find

The first Dimorphodon specimen was discovered in 1828 by Mary Anning, one of the most important fossil hunters in history. Anning found the specimen in the coastal cliffs of Lyme Regis, Dorset, England — the same stretch of coast where she had previously discovered the first Ichthyosaurus and Plesiosaurus specimens.

The famous paleontologist Richard Owen formally described and named the animal in 1859, recognizing the significance of its unusual two-type tooth arrangement.

In Popular Culture

The “Piranhas of the Air”

In Jurassic World (2015), flocks of Dimorphodon were depicted as aggressive, swarming pests that attacked tourists alongside Pteranodons. This scene cemented their reputation as “flying piranhas,” although the real animal was likely much more timid and would have been terrified of large animals like humans.

The movie also dramatically increased Dimorphodon’s size — the film versions are much larger and more aggressive than the real 1-meter, 2 kg animal. In reality, a Dimorphodon would have been about the size and weight of a pigeon, though with a much larger head.

Frequently Asked Questions

Q: Was it a dinosaur? A: No, it was a pterosaur — a flying reptile. Pterosaurs are closely related to dinosaurs but belong to a separate group. Dinosaurs generally didn’t fly (until they evolved into birds).

Q: Could it walk on land? A: Yes, and probably very well! Its strong legs and clawed feet suggest it was a capable climber and runner. It may have spent significant time on the ground hunting insects.

Q: Why was its head so big? A: The large skull housed strong jaw muscles for its varied diet, but the bone was very thin and full of weight-saving openings. Despite looking heavy, the skull was remarkably lightweight.

Q: How does it compare to Pteranodon? A: Dimorphodon was much smaller (1 m vs 6 m wingspan), had teeth (Pteranodon was toothless), and was a less capable flyer. They lived about 100 million years apart — Dimorphodon in the Early Jurassic, Pteranodon in the Late Cretaceous.

Q: Could it really attack humans like in Jurassic World? A: No. At only 2 kg, Dimorphodon was far too small to pose any threat to a human. It would have been more likely to flee from people than attack them.