Dimorphodon, an early pterosaur from the Early Jurassic period (201 to 191 million years ago), presents an intriguing case due to its distinctive anatomy. This flying reptile was notable for having an oversized, bulky skull relative to its body, setting it apart from many of its contemporaries. Determining what Dimorphodon consumed involves examining its fossilized remains to understand the function of its unique biological structures.
Anatomical Evidence from the Skull and Teeth
The most compelling evidence for the diet of Dimorphodon is preserved within its skull, a structure that is both large and surprisingly lightweight. This lightness was achieved through numerous large openings (fenestrae) separated by thin bony partitions, providing structural strength without excessive mass. The sheer size of the skull, which could reach about 23 centimeters, suggested a powerful feeding apparatus, yet the mechanics of its jaws revealed a more nuanced function.
The name Dimorphodon itself, meaning “two-form tooth,” points directly to its unique dentition, a feature known as heterodonty that is rare among reptiles. The front of the upper jaw was armed with four or five pairs of long, sharp, fang-like teeth, ideally suited for piercing and securing prey. These anterior teeth were much larger and more widely spaced than the teeth further back in the jaw.
Following these prominent front teeth, the rear sections of the jaws contained numerous smaller, flattened, and bladelike teeth. This dual dentition suggests Dimorphodon required both an initial gripping mechanism and a subsequent, though limited, means of processing food. Biomechanical analyses indicate a “snap and hold” feeding method: the jaws closed quickly but with a relatively low bite force. This low force would have been insufficient for crushing bones or piercing the tough scales of large fish, challenging earlier assumptions that it was a specialized fish-eater (piscivore).
Habitat and Locomotion Clues
The environment in which Dimorphodon fossils were discovered offers further clues about its lifestyle and, by extension, its diet. The most significant specimens were found in the coastal deposits of the Jurassic Coast in southern England, particularly near Lyme Regis. While a coastal location might initially suggest a marine-based diet, a closer look at the animal’s body plan suggests a strong connection to the land.
Dimorphodon possessed relatively short and robust wings compared to later pterosaurs that were built for long-distance soaring over open water. This morphology implies that it was not an especially graceful or efficient flier, likely restricted to short bursts of flight. Furthermore, its hind limbs were well-developed, and its feet were large, indicating a greater proficiency for terrestrial locomotion than many of its aerial relatives.
The short wings and strong limbs suggest that Dimorphodon spent substantial time on the ground or climbing the trees and cliffs of the coastal landscape. This ability to move efficiently on land points toward a hunting strategy focused on prey found near the ground or within the coastal forest ecosystem. Its association with the shore may have been a matter of convenience, using the cliffs as roosting sites and the adjacent land as its primary foraging ground.
Scientific Consensus on Prey
Synthesizing the evidence from its anatomy and habitat leads most paleontologists to conclude that Dimorphodon was a generalized, opportunistic carnivore. The combination of a large, rapid-closing jaw and heterodont teeth suggests a diet composed of small animals that could be quickly snatched and immobilized. The low bite force, however, indicates that it likely avoided prey that required extensive crushing or struggled forcefully.
Scientists believe that small terrestrial vertebrates, such as lizards and early mammals, would have been common targets, as they are easily grasped by the fang-like front teeth. Large insects also constituted a significant part of its diet, fitting the “snap and hold” method perfectly. The sheer size of Dimorphodon suggests it was too large to rely solely on small invertebrates, necessitating the inclusion of larger prey items.
While not a specialized piscivore, Dimorphodon likely did not ignore the abundance of food at the coast. It may have occasionally caught small fish or crustaceans near the shore, or more likely, scavenged carrion that washed up from the sea. Overall, the evidence paints a picture of a versatile feeder that exploited the readily available resources of its coastal ecosystem, balancing its diet between the land and the nearby marine margin.