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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 Dorygnathus ("spear jaw") was a genus of pterosaur that lived in Europe during the Early Jurassic period, 180 million years ago when shallow seas flooded much of the continent. It had a short 1.5 meter (five feet) wingspan, and a relatively small triangular sternum, which is where its flight muscles attached. Its skull was long and its eye sockets were the largest opening therein. Large curved fangs that "intermeshed" when the jaws closed featured prominently at the front of the snout while smaller, straighter teeth lined the back. Having variable teeth, a condition called heterodonty, is rare in modern reptiles but more common in primitive pterosaurs. The heterodont dentition in Dorygnathus is consistent with a piscivorous (fish-eating) diet. The fifth digit on the hindlimbs of Dorygnathus was unusually long and oriented to the side. Its function is not certain, but the toe may have supported a membrane like those supported by its wing-fingers and pteroids. Dorygnathus was according to David Unwin related to the Late Jurassic pterosaur, Rhamphorhynchus and was a contemporary of Campylognathoides in Holzmaden and Ohmden.

 Dorygnathus in general has the build of a basal, i.e. non-pterodactyloid pterosaur: a short neck, a long tail and short metacarpals — although for a basal pterosaur the neck and metacarpals of Dorygnathus are again relatively long. The skull is elongated and pointed. The largest known cranium, that of specimen MBR 1920.16 prepared by Bernard Hauff in 1915 and eventually acquired by the Humboldt Museum in Berlin, has a length of sixteen centimetres. In the skull the eye socket forms the largest opening, larger than the fenestra antorbitalis that is clearly separated from the slit-like bony naris. No bony crest is visible on the rather straight top of the skull or snout. The lower jaws are thin at the back but deeper toward the front where they fuse into the symphysis ending in a toothless point after which the genus has been named. In MBR 1920.16, the mandibula as a whole has a length of 147 millimetres.

 In the lower jaws the first three pairs of teeth are very long, sharp and pointing outwards and forwards. They contrast with a row of eight or more upright-standing much smaller teeth that gradually diminish in size towards the back of the lower jaw. No such extreme contrast exists in the upper jaws, but the four teeth in the premaxilla are longer than the seven in the maxilla that again become smaller posteriorly. The total number of teeth is thus at least 44. The long upper and lower front teeth interlaced when the beak was closed; due to their extreme length they then projected considerably beyond the upper and lower margins of the head.

 According to Padian, eight cervical, fourteen dorsal, three or four sacral and twenty-seven or twenty-eight caudal vertebrae are present. The exceptional fourth sacral is the first of the normal caudal series. The number of caudals is not certain because their limits are obscured by long thread-like extensions, stiffening the tail. The cervical vertebrae are rather long and strongly built, their upper surface having a roughly square cross-section. They carry double-headed thin cervical ribs. The dorsal vertebrae are more rounded with flat spines; the first three or four carry ribs that contact the sternal ribs; the more posterior ribs contact the gastralia. The first five or six, rather short, caudal vertebrae form a flexible tail base. To the back the caudals grow longer and are immobilised by their intertwining extensions with a length of up to five vertebrae which together surround the caudals with a bony network, allowing the tail to function as a rudder.

 The breastbone is triangular and relatively small; Padian has suggested it may have been extended at its back with a cartilaginous tissue. It is connected to the coracoid which in older individuals is fused to the longer scapula forming a saddle-shaped shoulder joint. The humerus has a triangular deltopectoral crest and is pneumatised. The lower arm is 60% longer than the upper arm. From the five carpal bones in the wrist a short but robust pteroid points towards the neck, in the living animal a support for a flight membrane, the propatagium. The first three metacarpals are connected to three small fingers, equipped with short but strongly curved claws; the fourth to the wing finger, in which the second or third phalanx is the longest; the first or fourth the shortest. The wing finger supports the main flight membrane.

 In the pelvis, the ilium, ischium and pubis are fused. The ilium is elongated with a length of six vertebrae. The lower leg, in which the lower two thirds of the tibia and fibula of adult specimens are fused, is a third shorter than the thighbone, the head of which makes an angle of 45° with its shaft. The proximal tarsals are never fused in a separate astragalocalcaneum; a tibiotarsus is formed. The third metatarsal is the longest; the fifth is connected to a toe of which the second phalanx shows a 45° bend and has a blunt and broad end; it perhaps supported a membrane between the legs, a cruropatagium.

 In some specimens, soft parts have been preserved but these are rare and limited, providing little information. It is unknown whether the tail featured a vane on its end, as with Rhamphorhynchus.   However, Ferdinand Broili reported the presence of hairs in specimen BSP 1938 I 49, an indication that Dorygnathus also had fur and an elevated metabolism, as is presently assumed for all pterosaurs.

 In 1971 Rupert Wild described and named a second species: Dorygnathus mistelgauensis, based on a specimen collected in a brick pit near the railway station of Mistelgau, to which the specific name refers, by teacher H. Herppich, who donated it to the private collection of Günther Eicken, a local amateur paleontologist at Bayreuth, where it still resides. As a result the exemplar has no official inventory number. The fossil comprises a shoulder-blade with wing, a partial leg, a rib and a caudal vertebra. Wild justified the creation of a new species name by referring to the great size, with an about 50% larger wingspan than with a typical specimen; the short lower leg and the long wing.

 Padian in 2008 pointed out that D. banthensis specimen MBR 1977.21, the largest then known, has with a wingspan of 169 centimetres an even larger size; that wing and lower leg proportions are rather variable in D. banthensis and that the geological age is comparable. He concluded that D. mistelgauensis is a subjective junior synonym of D. banthensis.

 Dorygnathus is commonly thought to have had a piscivorous way of living, catching fish or other slippery sea-creatures with its long teeth. This is confirmed by the fact that the fossils have been found in marine sediments, deposited in the seas of the European Archipelago. In these it is present together with the pterosaur Campylognathoides that however is much more rare. Very young juveniles of Dorygnathus are unknown, the smallest discovered specimen having a wingspan of sixty centimetres; perhaps they were unable to venture far over open sea. Padian concluded that Dorygnathus after a relatively fast growth in its early years, faster than any modern reptile of the same size, kept slowly growing after having reached sexual maturity, which would have resulted in exceptionally large individuals with a 1.7 metres wingspan.

 On land, Dorygnathus was probably not a good climber; its claws show no special adaptations for this type of locomotion. According to Padian, Dorygnathus, as a small pterosaur with a long tail, was well capable of bipedal movement, though its long metacarpals would make him better suited for a quadrupedal walk than most basal pterosaurs. Most researchers however, today assume quadrupedality for all pterosaurs.

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

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