DIMORPHODON

genus of extinct flying reptiles found as fossils in European deposits from the Early Jurassic Period (occurring 208 to 187 million years ago). Dimorphodon, among the most primitive of the known pterosaurs (flying reptiles), was about 1 m (3 feet) long. The head was very large and deep, and the skull had several large openings. Two types of teeth are found in the jaws: several large pointed ones in the front and many smaller teeth in the back. The limbs were well developed; it is unclear whether the animal habitually walked on two legs. The wings consisted of thin membranes of skin that stretched from the enormously elongated fourth finger of each hand to the hind limbs. On the ground, the animal probably folded its wings, much as do modern bats. The three remaining fingers of each forelimb were well developed and probably able to support the animal on the ground; these fingers also were used for grasping and were clawed. The eyes were large. Dimorphodon certainly was not as efficient a flier as the modern birds; it lacked the large keel to which the powerful flight muscles of birds are attached; gliding rather than wing beating was probably the normal mode of flight for the animal.