Диморфодон (двуформозуб) — вымершее летающее пресмыкающееся, жившее от 200 до 180 миллионов лет назад. Размах крыльев до 2 м, длина от кончика головы до кончика хвоста — 120 см, размер головы — до 30 см.

 Диморфодон – один из древнейших летающих динозавров (птерозавров), обитавший в юрском периоде. Этот ящер имел мощные крылья, размах которых составлял около 2 метров. Длина его тела с учётом хвоста составляла 1,2 метра, а размер головы около 30 сантиметров.

 Вытянутая передняя часть головы напоминала клюв, но, в отличие от аналогичной части тела современных птиц, он был усажен огромным количеством острых, загнутых назад зубов. Как на задних конечностях, так и на концах крыльев располагались острые когти. Всё это говорит о том, что диморфодон был хищником, но, судя по небольшим размерам, питался он в основном рыбой и насекомыми. Вероятно, диморфодоны могли не только летать, но и лазать по деревьям и даже несколько неуклюже передвигаться по суше, используя при этом все 4 конечности.

 Вид этот изучен довольно слабо, так как на данный момент были найдены останки лишь одного экземпляра на территории Англии. Вполне возможно, что диморфодоны обитали не только в Европе.

 Dimorphodon had a large, bulky skull approximately 22 centimetres in length, whose weight was reduced by large openings separated from each other by thin bony partitions. Its structure, reminiscent of the supporting arches of a bridge, prompted Richard Owen to declare that, in far as achieving great strength from light-weight materials was concerned, no vertebra was more economically constructed; Owen saw the vertebrate skull as a combination of four vertebrae modified from the ideal type of the vertebra. The front of the upper jaw had four or five fang-like teeth followed by an indeterminate number of smaller teeth; the maxilla of all exemplars is damaged at the back. The lower jaw had five longer teeth and thirty to forty tiny, flattened pointed teeth, shaped like a lancet. Many depictions give it a speculative puffin-like 'beak' because of similarities between the two animals' skulls.

 The body structure of Dimorphodon displays many "primitive" characters, such as, according to Owen, a very small brain-pan and proportionally short wings. The first phalanx in its flight finger is only slightly longer than its lower arm. The neck was short but strong and flexible and may have had a membraneous pouch on the underside. The vertebrae had pneumatic foramina, openings through which the air sacks could reach the hollow interior. Dimorphodon had an adult body length of 1 metre (3.3 ft) long, with a 1.45 meter (4.6 ft) wingspan.

 The tail of Dimorphodon was long and consisted of thirty vertebrae. The first five or six were short and flexible but the remainder gradually increased in length and were stiffened by elongated vertebral processes. The terminal end of the tail may have borne a Rhamphorhynchus-like tail vane, although no soft tissues have yet been found of Dimorphodon to confirm this speculation

 Owen saw Dimorphodon as a quadruped. He speculated that the fifth toe supported a membrane between the tail and the legs and that the animal was therefore very ungainly on the ground. His rival Harry Govier Seeley however, propagating the view that pterosaurs were warm-blooded and active, argued that Dimorphodon was either an agile quadruped or even a running biped due to its relatively well developed hindlimbs and characteristics of its pelvis. This hypothesis was revived by Kevin Padian in the nineteen eighties. However, fossilised track remains of other pterosaurs (ichnites) show a quadrupedal gait while on the ground and these traces are all attributed to derived pterosaurs with a short fifth toe. Dimorphodon's was elongated, clawless, and oriented to the side. David Unwin has therefore argued that even Dimorphodon was a quadruped, a view confirmed by computer modelling by Sarah Sangster.

 Our knowledge of how Dimorphodon lived is limited. It perhaps mainly inhabited coastal regions and might have had a very varied diet. Buckland suggested it ate insects. Later it became common to depict it as a piscivore (fish eater), though Buckland's original idea is more well supported by biomechanical studies. Dimorphodon had an advanced jaw musculature specialized for a "snap and hold" method of feeding. The jaw could close extremely quickly but with relatively little force or tooth penetration. This, along with the short and high skull and longer, pointed front teeth suggest Dimorphodon was an insectivore, though it may have occasionally eaten small vertebrates and carrion as well.

 In 1870 Seeley assigned Dimorphodon its own family, the Dimorphodontidae, with Dimorphodon as the only member. It was suggested in 1991 by German paleontologist Peter Wellnhofer that Dimorphodon might be descended from the earlier European pterosaur Peteinosaurus. Later exact cladistic analyses are not in agreement. According to Unwin, Dimorphodon was related to, though probably not a descendant of, Peteinosaurus, both forming the clade Dimorphodontidae, the most basal group of the Macronychoptera and within it the sister group of the Caelidracones. This would mean that both dimorphodontid species would be the most basal pterosaurs known with the exception of Preondactylus. According to Alexander Kellner however, Dimorphodon is far less basal and not a close relative of Peteinosaurus.

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Tags: Вымершие рептилии, Юра, авеметатарзалии, архозавроморфы, архозавры, диапсиды, диморфодонтиды, птерозавры, рамфоринхоидеи

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 Peteinosaurus (pronounced /pɛˌtaɪnəˈsɔrəs/ or /pɛˌtinəˈsɔrəs/) was a prehistoric reptile genus belonging to the Pterosauria. It lived in the late Triassic period in the middle Norian (about 221-210 million years ago).

 Three fossils have been found near Cene, Italy. The first fossil, the holotype MCSNB 2886, is fragmentary and disarticulated. The second, the articulated paratype MCSNB 3359, lacks any diagnostic features of Peteinosaurus and thus might be a different species. This paratype has a long tail (20 cm) made more stiff by long extensions of the vertebrae; this feature is common among pterosaurs of the Triassic. The third exemplar is MCSNB 3496, another fragmentary skeleton. All specimina are those of subadults and of none has the skull been preserved.

 Like most pterosaurs, Peteinosaurus had bones that were strong but very light. Peteinosaurus is trimorphodontic, with three types of conical teeth. An insectivorous lifestyle has been attributed to Peteinosaurus. The fifth toe of Peteinosaurus was long and clawless. Its joint allowed it to flex in a different plane than the other phalanges, an adaptation whose function is unknown.

 Peteinosaurus is one of the oldest-known pterosaurs, and at a mere sixty centimetres, had a tiny wingspan when compared to some later genera, such as Pteranodon whose wingspan exceeded twenty feet. Its wings were also proportionally smaller than those of later pterosaurs, as its wing length was only twice the length of the hindlimb. All other known pterosaurs have wingspans at least three times the length of their hindlimbs. It also had single cusped teeth that lacked the specialized heterodonty present in the other Italian Triassic pterosaur genus, Eudimorphodon.

 All these factors converge to hint that Peteinosaurus belongs to a group that possibly represents the most basal known pterosaurs: the Dimorphodontidae, to which it was assigned in 1988 by Robert L. Carroll. The only other known member of that group is the later genus Dimorphodon, which lent its name to the family including both genera. Later cladistic analyses however, have not shown a close connection between the two forms. Nevertheless the possible basal position of Peteinosaurus has been affirmed by Fabio Marco Dalla Vecchia who suggested that Preondactylus, according to David Unwin the most basal pterosaur, might be a subjective junior synonym of Peteinosaurus. A 2010 cladistic analysis by Brian Andres and colleagues placed Peteinosaurus in Lonchognatha which includes Eudimorphodon and Austriadactylus as more basal.

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Tags: Вымершие рептилии, Триас, авеметатарзалии, архозавроморфы, архозавры, диапсиды, диморфодонтиды, птерозавры, рамфоринхоидеи

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