Dimorphodon is a medium-sized species of pterosaur that first originated in the early-to-mid-Jurassic Period, 195 to 190 million years ago. The name Dimorphodon translates to “two-form tooth.” This refers to the animal’s two different varieties of teeth, a trait that is rare among reptiles. Its specific epithet macronyx means “large claw,” referring to the size of the claws on its hands. Discovered at Lyme Regis in the United Kingdom (now a World Heritage Site, known as the “Jurassic Coast”) in 1828 by fossil collector Mary Anning, Dimorphodon was originally classified under the genus Pterodactylus. It would later be reclassified by Richard Owen in 1858 after discovering its skull. Remains of this genus are rare, but some have been identified from Aust Cliff in southwestern England.
A second, larger species of Dimorphodon was discovered in 1998 in Huizachal Canyon at La Boca Formation, northeastern Mexico. It was named Dimorphodon weintraubi by its discoverer James Clark; the specific epithet here is intended to honor Dr. Robert L. Weintraub.
International Genetic Technologies succeeded in obtaining DNA from Dimorphodon prior to 1993, but the viability rate of the species was at 36% at the time of the incident due to the genome’s incomplete status. Over a decade later, InGen’s new parent company Masrani Global Corporation completed the genome and was able to clone the animal. The species cloned by InGen is presumed to be D. macronyx because it is slightly more common and better-known, and more tentatively because D. weintraubi was not discovered until after InGen identified its Dimorphodon DNA. The Jurassic World website does mention Dimorphodon as being found in both England and Mexico, however, and there are instances of InGen referring to species such as Suchomimus that, in real life, had not yet been discovered at the time the documents were written. It is also possible that, like InGen’s Velociraptor, gene splicing techniques and poor record-keeping have resulted in today’s Dimorphodons potentially containing DNA from both fossil species.
Compared to InGen’s other pterosaur species, Pteranodon, the Dimorphodon is comparatively small. It grows to 2.3 meters (8ft) long including the tail, weighing around three pounds. When standing on its hind legs, it is about 3.2 feet tall; despite being winged, it walks with a quadruped gait, as its legs are not built for running. Its wingspan is about 4.6 feet. Dimorphodon‘s wings are not as powerful as those of more advanced pterosaurs; rather than lengthy bouts of powered flight or gliding, this creature is suited to short, frantic flights. It is also known to ride in the wakes of larger pterosaurs and aircraft to conserve energy.
Dimorphodon‘s most striking feature is its large head, which appears disproportionate for its body size and is unusually boxy in shape. The skull shape of the genetically-engineered specimens created by Masrani Global Corporation is more rectangular than fossil specimens, which were still quite bulky but with a rounded snout. In fossil specimens, there are five fang-like teeth in the front of each jaw, which are absent in those cloned by InGen, followed by thirty to forty small, narrow sharp teeth. The de-extinct specimens have mouths entirely full of long, needle-like teeth, a marked difference from the unique dentition of the original animal.
The skull is lightened by large apertures in the bone, which are plainly visible on InGen’s Dimorphodons due to the “shrink-wrapped” appearance of their skin (a feature which is almost certainly the result of genetic engineering, rather than the animal’s natural appearance). Another feature present on InGen’s specimens, but not those known from fossils, is the presence of large supraorbital ridges like those seen on some theropod dinosaurs. These can be observed over the eyes, which are relatively large and possess round pupils and yellow sclerae. The musculature of the jaws is quite advanced, allowing the Dimorphodon to execute rapid snapping bites. However, its bite force is weak, and the teeth do not penetrate very deep. It has a relatively long, thin, pointed tongue, which cannot extend out of the mouth.
Like all pterosaurs, the wings of Dimorphodon are supported by the fourth finger of the hand, which is greatly elongated. The membrane of the wing, called the patagium, is divided into two parts: the propatagium, which extends from the shoulder to the wrist, and the brachiopatagium, which extends from the fourth finger to the leg.
Dimorphodon possesses quite powerful limbs and large curved claws on its wings and feet, which enable it to climb excellently. It is depicted doing so in the mobile game Jurassic World: The Game, which shows the pterosaur as able to climb trees with a saltatorial gait rather like a squirrel. It is also shown to be capable of brief bipedal running, using its wings for stability; however, it walks on all fours virtually all the time. It is built with a low center of gravity, which further enhances its climbing ability.
Unlike the pterodactyloid pterosaurs, Dimorphodon possesses a lengthy tail which may be longer than the rest of the body. Its tail consists of thirty vertebrae, and terminates in a rudder-like structure which is presumably used for steering during its brief moments of flight. Its tail is left free, rather than being connected to the wings or legs by patagia.
Coloration of this species is variable but generally dark. Most are gray, but may have tints of blue; others appear pale green, while some are closer to black. The wings, generally, are lighter-colored than the body, and it is common for the face to have pink tints. Darker stripes may be present on the back, and the snout may have a dark pinkish-gray stripe as well as reddish skin around the eyes.
On the dorsal side, Dimorphodon has a coating of pycnofibers (a type of structure analogous to hair or feathers) which presumably assist with retaining heat.
Individuals of varying sizes have been observed, but the animal’s growth rate is not known. Smaller, and thus presumably younger, Dimorphodons have generally narrower jaws and lighter build, but appear proportionally similar to the older animals. Pterosaurs in general are believed to have been fully capable of flight shortly after hatching, and so would not have undergone a great many physical changes during maturation.
As of now, there is no way to accurately sex a Dimorphodon. The sexes of individuals observed so far have not been identified, though the Jurassic World: The Game and Jurassic World Facts mobile applications describes the animals featured there as females. The animals in these applications more or less resemble those seen on Isla Nublar in 2015, so it can be inferred that at least some of those present at the time were definitively female.
Jurassic World’s staff housed Dimorphodon in an aviary with numerous cliffs, trees, and shallow rivers. The structure had an area of 430,000 square feet. However, personnel cited by the Dinosaur Protection Group after the 2015 Isla Nublar incident suggested that these conditions were inadequate for the animals, and that they would need a larger body of water in their habitat as well as more living space. During the incident, they instinctively flocked to the nearest large body of water, the Jurassic World Lagoon, suggesting that they tolerate salt water.
Sometime between 2005 and 2014, Masrani Global Corporation cloned Dimorphodon macronyx, housing the species in the Jurassic World Aviary. On December 18, 2015, at least 43 Dimorphodon were observed on the island.
During the incident of December 18, 2015, the pterosaurs were frightened out of the aviary due to a combination of a break-in by the escaped Indominus rex and subsequent vehicular accident. They followed the larger Pteranodons westward, then turning to the southeast to approach Sector 3. Upon arriving there, they established Main Street and the Boardwalk as hunting and nesting territory. During the incident, multiple animals were tranquilized in mid-flight; at least seven died due to internal injury or drowning in the Lagoon after being sedated. An eighth presumably died due to an overdose of tranquilizers delivered by Senior Assets Manager Claire Dearing during the incident.
At least one individual reached the island’s eastern coast, but was gunned down by InGen Security while flying alongside a helicopter.
No Dimorphodons were encountered during either the June 2016 retrieval mission to that same area (presumably due to the inclement weather) or the June 23, 2018 mission. However, a poster released in February 2017 by the Dinosaur Protection Group implied that Dimorphodon was extant at the time, presumably in regions of the island not extensively surveyed during either incident. It is not known how many, if any, Dimorphodon survived the eruption of Mount Sibo on June 23.
While InGen’s operations originally took place on Isla Sorna, the viability of Dimorphodon was insufficient to clone any at the time. It is not known whether any migrated to this island following their release from the Jurassic World Aviary.
Dimorphodon has been shown to have the instinct to flock toward large saltwater bodies, and at least one attempted to leave Isla Nublar on December 18, 2015. It is not known if any others have attempted to leave the island since, or if they have succeeded. If any did leave the island and survive the overseas journey, they would most likely have settled in Central America.
Behavior and Ecology
While this reptile has been observed as active during the day, the Jurassic World website’s advertisement for the Romance Package describes them as being vocal at night. This suggests that the animals are normally crepuscular or nocturnal, which their large eyes also suggest; they may socialize in the evening or at night. Interference from their artificial environment may have encouraged cathermal behavior patterns; visitors and staff likely caused the Dimorphodons to be active intermittently throughout the day.
Diet and Feeding Behavior
As a carnivore, the Dimorphodon feeds mainly on small animals. Insects and fish constitute a large amount of its diet; this suggests that it feeds low to the ground. Its jaws are not designed for puncturing flesh, but rather for entrapping prey; it uses its excellent eyesight to locate a food item, then quickly closes its jaws around the victim. The long claws of the toes may also be used to help capture prey. Its quick, biting attacks have led to it being characterized as a “snap-feeder.”
However, these animals can also act in large swarms to overwhelm groups of prey that they could not take down on their own. They have been observed engaging in feeding frenzies alongside Pteranodon; both genera of pterosaur will frighten and disorient groups of prey by dive-bombing, making loud vocalizations, and knocking debris around. While the prey items are panicked and confused, the pterosaurs will pick off the most vulnerable prey. Dimorphodons may tackle larger prey feet-first to knock them over, pull them off of ledges if they try to escape by climbing, and bite vulnerable areas. Because of the weak jaws of the Dimorphodon, it relies on a preliminary physical attack to incapacitate larger prey before biting. Its snout is surprisingly resilient, and it is capable of delivering a moderate headbutt in flight without injuring itself. When pinning down larger prey, it may beat its wings to maintain balance and disorient the prey.
Such feeding frenzies are presumed to be rare events, though. Typically, Dimorphodon cannot kill prey larger than itself. In fact, a feeding frenzy of this type has only been observed once, and is believed to have been caused by stress and understimulation in both species.
While Dimorphodon are moderately aggressive toward most other species, they are actually quite gregarious among themselves. Even after leaving the confines of the Jurassic World Aviary, the Isla Nublar flock remained mostly close together as it journeyed across the island. Feeding and nesting appear to be done communally, and the pterosaurs are highly vocal with one another. Despite this, they are not known to interact with each other physically, maintaining a sense of personal space.
On occasion, Dimorphodon may venture away from the flock, and appear to have no discomfort about being on their own in unfamiliar territory.
As with all pterosaurs, Dimorphodon lay eggs, and most likely have cloacae which are used to mate. Other better-studied pterosaurs are not known to show a large degree of parental care; Pteranodon will feed and protect flaplings in its neighborhood, but it may also abandon the young at a fairly early age if they are not its own offspring. The exact behaviors of Dimorphodon in particular with regards to reproduction are not known, but it appears that multiple age groups coexist within the same flock.
While medium to small dinosaur eggs incubate for a period of several months (as do the eggs of larger pterosaurs like Pteranodon), the incubation period of Dimorphodon is unknown.
As a social animal, it should come as no surprise that the Dimorphodon is highly vocal. It makes a variety of chirping and gibbering sounds to communicate with others of its own kind, though the nature of these communications (i.e. to identify food sources, advertise to mates, or establish dominance) have not been studied. In particular, the chirping sounds are said to be made during the night. When frightened or aggressive, Dimorphodon makes clicking or chittering noises, and can sometimes be heard screeching when agitated. When faced with a threat, it will usually make such noises before taking flight, suggesting that this sound is meant to signal to the others to follow that individual along a possible route to safety.
Non-vocal communications are also known from this species; when angered, it will rear onto its hind legs and spread its wings in an intimidation display. This serves a dual purpose: it can be used to intimidate predators or territorial rivals, and also signals to other Dimorphodon that there is a threat being addressed.
Prey of the Dimorphodon includes mainly small animals such as insects, fish, and reptiles. It would, therefore, be low on the food chain; it can mostly only eat prey that fits in its mouth, only attacking larger prey when it is in a frenzied state. Because its jaws are not designed for biting off pieces of meat, it is unlikely that it could feed properly from larger carcasses.
As with most de-extinct species, Dimorphodon would have been affected by hematophagous (blood-drinking) parasites in its native time period. Mosquitoes are a common example of hematophagous creatures. It is not known if any modern parasites affect Dimorphodon this way.
Because of its smaller size and weak bite, Dimorphodon tends to be less aggressive and more cautious around other animals. It is shy and easily spooked, though, which can provoke it to attack.
This species appears to associate willingly with Pteranodon longiceps masranii, though the latter is not always seen alongside Dimorphodon. The nature of this relationship is likely commensal, though it may possibly be parasitic. Competition between the two for food sources appears to be nonviolent, and the Pteranodon tolerate the Dimorphodon nearby; they have not been observed to attack or threaten their smaller neighbors in any way. The Dimorphodon, on the other hand, benefit from the presence of Pteranodon in several ways. Most of these are commensal, in that they benefit the Dimorphodon without harming the Pteranodon. This may include protection from some predators, as the aggressive Pteranodon will drive away most animals. For example, when the pterosaurs’ territory was perceived as threatened by the helicopter JW001, the Pteranodon confronted the threat while the Dimorphodon remained within the aviary walls. The Pteranodon are also much more powerful fliers; the Dimorphodon are weak fliers, but can be seen riding along in the wake of the Pteranodon even when safer or more comfortable routes are available. This suggests that they use the drafts created by Pteranodon to cover distance more quickly.
There is another element to the relationship that is possibly parasitic; during the December 18, 2015 incident, Pteranodon were attacked by both Indominus rex and Mosasaurus maximus. In both cases, Dimorphodon were also present, but the predators ignored them in favor of the larger pterosaurs. This pattern suggests that Dimorphodon may use the larger size of their neighbors to evade notice by large predatory animals.
It is not known if any Dimorphodon still inhabited the area surrounding the Jurassic World Lagoon by 2018, as the Pteranodon had mostly migrated north. If any remained, they would have shared territory with Dilophosaurus, Compsognathus, Brachiosaurus, and (at times) Tyrannosaurus. It is unlikely that these larger dinosaurs would interact with the comparatively minute Dimorphodon, but Compsognathus would probably compete with it for food, and the nocturnal Dilophosaurus may have preyed upon it.
Relationship to Humans
After they were cloned sometime in the mid-2000s or early 2010s, Dimorphodon were put on display in the Jurassic World Aviary alongside the much larger Pteranodon. Prior to this, InGen had identified ancient DNA as belonging to this genus, but was unable to clone the animal.
Advertisements for the aviary heavily focused on Pteranodon, with Dimorphodon being mostly ignored in marketing. It was, however, referenced in the Romance Package, with Masrani Global describing the chirping sounds of the animals as a part of the nighttime ambiance for couples sleeping in tents under the stars.
Following their accidental escape from the aviary, the Dimorphodon of Isla Nublar participated in a feeding frenzy on Main Street in which the human guests were, unfortunately, the prey. The frenzy resulted in numerous injuries, though the larger Pteranodon were primarily responsible. There are no confirmed deaths as a direct result of Dimorphodon attacks, but their already low popularity did them no favors as the incident became a symbol of de-extinct animals being somehow more dangerous than naturally extant animals. Though Pteranodon remained much more prominent in pro-extinction symbolism, Dimorphodon has also retained a reputation for being dangerous, menacing, and undesirable.
However, the stereotype of Dimorphodon as a bloodthirsty monster is far from deserved. Following the incident, experts cited by the Dinosaur Protection Group stated that the Jurassic World Aviary’s conditions were insufficient for the pterosaurs’ needs; for example, the area was too small, lacking a significant body of water beyond the small rivers present in the enclosure. Furthermore, they were unable to find the stimulation provided by active hunting as they would in the wild; despite their presumed low intelligence, this led them to become stressed. The resultant attack, these experts suggest, was the result of subpar care provided by Jurassic World staff rather than the inherent nature of the pterosaurs.