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Scientific Classification
Kingdom: Animalia
Phylum: Chordata
Order: Pterosauria
Family: Eudimorphodontidae
Genus: Eudimorphodon
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The Eudimorphodon was a pterosaur that existed on the earth in the late Triassic period. Pterosaurs were the earliest known flying reptiles. They are many a times referred to as flying dinosaurs but this assertion is incorrect. Pterosaurs have likely evolved from archosaurs and they are closely related to birds. But they are not included in clade Dinosauria and hence cannot be termed as dinosaurs.
The time period of existence of the Eudimorphodon was 212 to 205 million years ago. This phase lies in the Norian and Rhaetian ages, which were the concluding stages of the Triassic period. This time was marked by the Triassic Jurassic extinction event, which exterminated many different forms of reptiles from the earth, allowing dinosaurs their dominance in the Jurassic period. It is unlikely that the Eudimorphodon became extinct due to this catastrophe but it is not impossible either.
The Eudimorphodon is one of the oldest known pterosaurs, yet it did not contain many primitive traits. Due to this, it has not been very useful in determining the origin of pterosaurs. Many hypotheses have been put forth, and dinosaurs, archosaurs and even prolacertiformes have been considered as their predecessors. But archosauriformes seem the most likely candidates.
This reptile was small animal, being 1 meter in length and weighing about 20 pounds.

The name Eudimorphodon is comprised of three parts and has Greek inspirations. The suffix ‘eu’ stands for ‘true’, ‘dimorph’ indicates ‘two physical forms’ and ‘odon’ denotes teeth. The dentition of this pterosaur showed differentiation of teeth and hence such a name was chosen for it.
Two species of this reptile are known today. The type species E. ranzii honors scientist Silvio Ranzi. The subspecies E. cromptonellus was name after Alfred Crompton. A diminutive form is used in the name as this species was very small.
The genus and type species was named by paleontologist Rocco Zambelli in 1973. The subspecies was defined and named by Jenkins in 2001.

Discovery of fossils

  • The holotype of the Eudimorphodon was discovered by Mario Pandolfi near Bergamo in Italy in 1973. He had found it rock formation comprising of shale stone. It was defined in the same year by Zambelli.
  • In the year 1995, two more fossils were recovered from and were assigned a new subspecies E. rosenfeldi by Dalla Vecchia. But Vecchia later realized that this were a separate genus of pterosaur and named it the Carniadactylus in 2009.
  • The early 1990s had yielded a juvenile specimen from Greenland which has been attributed to the Eudimorphodon. It had wingspan of a mere 24 centimeters and has been named the subspecies E. cromptonellus.
  • A few jaw fragments were also discovered from the Dockum Group of Texas in 1986 that contained teeth which were similar to those of the Eudimorphodon. But these fossils have been deemed inadequate to be conclusively linked to the Eudimorphodon.
  • Many more specimens have been recovered from Italy that have been attributed to this reptile, making it the most abundant pterosaur of Italy in terms of numbers of fossils.

The Eudimorphodon is presently classified under order Pterosauria, family Eudimorphodontidae and subfamily Eudimorphodontinae. It is clear that this pterosaur is the type genus for both its family and subfamily.
The family Eudimorphodonontidae contains basal pterosaurs that showed dental differentiation. It was defined by Peter Wellnhofer in 1978. The subfamily Eudimorphodontinae includes those pterosaurs that are more closely related to the Eudimorphodon as compared to the Raeticodactylus.
It lacked primitive features despite of being a very old genus. The only basal features it displayed were the presence of pterygoid teeth and a flexible tail; younger pterosaurs possessed a stiff tail. Due to this, and the scarcity of older pterosaur fossils, its relationship with other retiles remains obscure.

The specialized teeth of the Eudimorphodon set it apart from other pterosaurs. Most of them either lacked dental dimorphism or did not have teeth at all.
The Eudimorphodon had about 55 teeth per jaw and its jaws were only 6 centimeter long. The tips of the jaws possessed long and sharp canine like teeth. These were suddenly continued as smaller teeth that were multi-cusped. The teeth at the base of the jaws aligned with each other when the snout of the reptile was close. This facilitated efficient chewing. They were designed for a piscivorous diet. Some of the teeth also showed severe wear and tear, indicating that the pterosaur ate shelled invertebrates.

Physical features

  • The Eudimorphodon was a small pterosaur. Its length was about 3.3 feet and its weight is estimated to be around 10 kilos. It was a slender built dinosaur.
  • The forelimbs of this pterosaur were lean. They contained four digits. The last of these was elongated and was attached to the wing membrane, along with the entire length of the foreleg.
  • The hind legs of the Eudimorphodon were also slender and were independent of the wing membrane.
  • The tail of this animal was long and thin and also contained a diamond shaped flap like the much younger pterosaur Rhampornychus. This feature is anachronistic for such and old pterosaur and it raises a lot of questions about the evolution of pterosaurs. It was possibly used as rudder while flying.

Habits and habitat
The Eudimorphodon was definitely an aerial reptile. It is likely that it could hobble on all four limbs on land as well. Its diet contained fish; one of the Eudimorphodon fossils had a Parapholidophorus fish fossil inside its ribcage, indicating the exact kind of fish it preferred. Its jaws were specially made for trapping and chewing fish. But it is also possible that it ate insects as well.
The habitat of this animal comprised of the coastal regions of Western Europe.

Related and coexisting species
The Eudimorphodon was related to the Peteinosaurus, Raeticodactylus and the Caviramus.
It possibly coexisted with the Saltriosaurus and the Peteinosaurus.

The final notes
It is possible that the Eudimorphodon and other pterosaurs underwent modular evolution. This means that not all body parts experience change in structure as time passes. This would explain how the Eudimorphodon showed characteristics of both primitive and derived pterosaurs.
Despite of a large number of fossils being ascribed to this genus, its phylogenetic relationships remain unknown, making the above mentioned explanation a conjecture. If and when more primitive pterosaurs may be discovered, the ancestry of the Eudimorphodon may be better understood.

Just for fun we have a soundclip available for you to hear what a Eudimorphodon could've sounded like. Click to the Dinosaur Sounds area to hear it. Please note that the dinosaur sounds are only for entertainment and are not an actual fact.