Сообщество, посвящённое ра - October 4th, 2011
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07:50 pm [industrialterro]
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Eryops
Эриопс (Eryops megacephalus) – представитель темноспондилов позднекаменноугольной - раннепермской эпохи. Типовой род семейства Eryopidae, один из самых известных темноспондилов. Крупное животное, с длиной черепа до 50 см, общая длина до 2 метров. Череп массивный, по очертаниям напоминает череп аллигатора, сильно скульптирован. Верхняя поверхность черепа несет продольные гребни позади глаз и ноздрей. Зубы крупные, развиты небные «клыки». Скелет массивный, конечности короткие, но мощные. Ребра расширены для укрепления грудной клетки. Тело боченковидное, остистые отростки спинных позвонков довольно высокие, лопатка мощная. На спине присутствуют единичные кожные чешуи. Таз массивный. Хвост средней длины. Вероятно, полуводный хищник. Род описан Э.Д. Коупом из ранней перми (вольфкамп) Техаса в 1877 году. Типовой вид - E. megacephalus. Примерно 5 – 6 видов из позднего карбона – ранней перми Северной Америки.
К семейству Eryopidae относятся также:
- Clamorosaurus – из поздней перми (уфимская эпоха) Северной России. Длина черепа около 23 см. 2 вида.
- Onchiodon – поздний карбон -ранняя пермь Западной Европы (Франция и Германия). Длина черепа более 15 см. Примерно 4 вида. Типовой вид - O. labyrinthicus. Branchiosaurus amblystomus и Pelosaurus laticeps – мелкие «стегоцефалы» из ранней перми Западной Европы – могут быть личинками типового вида онхиодона, хотя не исключено, что это личинки Sclerocephalus.
- К семейству могут принадлежать также Euchirosaurus и Osteophorus из ранней перми Западной Европы.
Род Sclerocephalus может также относиться к эриопидам, хотя иногда его выделяют в особое семейство и сближают с архегозаврами.
The skull of Eryops is proportionately large, being broad and flat and reaching lengths of 60 centimeters (2 ft). The skull resembled that of a salamander. It had an enormous mouth with many sharp teeth in strong jaws. Its teeth had enamel with a folded pattern, hence its classification with the labyrinthodonts ("maze toothed"). Within the wide, gaping jaw, the fang-like palatal teeth, when coupled with the gape, suggest an inertial feeding habit. This is when the amphibian would grasp its prey and, lacking any chewing mechanism, toss its head up and backwards, throwing the prey farther back into its mouth. Such feeding is seen today in the crocodile and alligator. It is taken that Eryops was not very active, thus a predatory lifestyle, while possible, was probably not the norm. It is more likely that it fed on fish either in the water or on those that became stranded at the margins of lakes and swamps. A large supply of terrestrial invertebrates were also abundant at the time, and this may have provided a fairly adequate food supply in itself.
Eryops’ eye sockets were large and directed upward. The body was low to the ground and supported by short, massive limbs. The tail was short, suggesting the animal was not a fast or powerful swimmer. The flat skull with the large eyes and nostrils placed on the top of the head are suggestive that Eryops used stealth for hunting, much like a modern crocodile, and sat quietly in the water waiting for prey with only its eyes and nostrils visible above the water.
The pectoral girdle of Eryops was highly developed, with a larger size for both increased muscle attachment to both it and the limbs. Most notably, the shoulder girdle was disconnected from the skull, resulting in improved terrestrial locomotion. The crossopterygian cleithrum was retained as the clavicle, and the interclavicle was well-developed, lying on the underside of the chest. In primitive forms, the two clavicles and the interclavicle could have grown ventrally in such a way as to form a broad chest plate, although such was not the case in Eryops. The upper portion of the girdle had a flat scapular blade, with the glenoid cavity situated below performing as the articulation surface for the humerus, while ventrally there was a large flat coracoid plate turning in toward the midline.
The pelvic girdle also was much larger than the simple plate found in fishes, accommodating more muscles. It extended far dorsally and was joined to the backbone by one or more specialized sacral ribs. The hind legs were somewhat specialized in that they not only supported weight, but also provided propulsion. The dorsal extension of the pelvis was the ilium, while the broad ventral plate was composed of the pubis in front and the ischium behind. The three bones met at a single point in the center of the pelvic triangle, called the acetabulum, providing a surface of articulation for the femur.
The main strength of the ilio-sacral attachment of Eryops was by ligaments, a condition structurally, but not phylogenetically, intermediate between that of the most primitive embolomerous amphibians and early reptiles. The condition that is more usually found in later vertebrates is that cartilage and fusion of the sacral ribs to the blade of the ilium are utilized in addition to ligamentous attachments.
Like most modern amphibians, Eryops breathed by inhaling air into lungs, where oxygen was absorbed and CO2 released. However, unlike modern amphibians, Eryops probably could not respire effectively through its skin, as its large size would have resulted in a low surface area to volume ratio. Unlike modern amphibians, its ribs were well-developed, but were immobile, preventing ventilation by expanding the body cavity. Thus, Eryops probably breathed via buccal pumping, in which the hyoid apparatus raises and lowers the floor of the mouth in order to pump air into the lungs.
Eryops had typical amphibian posture exhibited by the upper arm and upper leg extending nearly straight out from its body, while the forearm and the lower leg extended downward from the upper segment at a near right angle. The body weight was not centered over the limbs, but was rather transferred 90 degrees outward and down through the lower limbs, which contacted the ground. Most of the animal's strength was used to just elevate its body off the ground for walking, which was probably slow and difficult. With this sort of posture, only short, broad strides could be achieved. This has been confirmed by fossilized footprints found in Carboniferous rocks.
Ligamentous attachments within the limbs were present in Eryops, being important because they were the precursor to bony and cartilagenous variations seen in modern terrestrial animals that use their limbs for locomotion.
The primary species of Eryops has been named Eryops megacephalus (“big head”).
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Tags: Вымершие амфибии, Карбон, Лабиринтодонты, Темноспондилы
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08:18 pm [industrialterro]
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Fedexia
Fedexia is an extinct genus of carnivorous temnospondyl within the family Trematopidae. It lived 300 million years ago during the late Carboniferous period. It is estimated to have been two feet long, and likely resembled a salamander. Fedexia is known from a single skull found in Pittsburgh, Pennsylvania. It is named after the shipping service FedEx, which owned the land where the holotype specimen was first found.
The holotype skull (CM 76867) was discovered on land owned by the FedEx Corporation near Pittsburgh International Airport in 2004. Adam Striegel, a student at the University of Pittsburgh, found the skull on a field trip to the area, but he mistook the teeth for a fern frond. It was later recognized as a skull by class lecturer Charles Jones, and was taken to the Carnegie Museum of Natural History for further study. The specific name of the type species honors Adam Striegel.
The holotype skull is 11.5 centimetres (4.5 in) long and is uncrushed and well preserved. Remarkably, the stapes, or middle ear bone, remains intact. Also preserved are both mandibles and the atlas-axis complex, which connects to the base of the skull.
Fedexia possesses several characteristics that identify it as a trematopid. One of the most noticeable is a greatly elongated and subdivided external naris. The posterior portion of the naris may have held a salt gland. Another characteristic is the presence of large palatal tusks. Based on small bony elements present in the related trematopid Anconastes, Fedexia likely had a granular skin texture formed by bony protuberances. These protuberances would have served as protection from predators and would have lessened water loss through the skin.
Unlike other trematopids, Fedexia has a tall, arching lateral profile to the skull. The margin forms a broad arc from the tip of the snout to the occipital region. Other trematopids have a lower, straighter profile to the skull. Another distinguishing feature is that the postorbital length, from the eyes to the back of the skull, is greater than the preorbital length, from the eyes to the tip of the snout. The orbits, or eye sockets, are vertically elongated, extending dorsally to the skull table. There is also a small notch on the premaxilla that separates the premaxillary teeth from the maxillary teeth.
Like all trematopids, Fedexia was well adapted to a terrestrial lifestyle. Trematopids are the earliest examples of vertebrate life in North America that lived mostly on land, although they likely returned to the water to mate and lay eggs. Fedexia is one of the oldest known vertebrates to have been primarily terrestrial rather than aquatic. Even older are the trematopids Actiobates and Anconastes, which are Missourian (Kasimovian) and early Virgilian in age, respectively. The shift toward a terrestrial lifestyle may have been a response the warmer and drier global climate that existed during the late Carboniferous. During this time, glaciation caused the climate to rapidly fluctuate and sea levels to drop. This resulted in a loss of coal swamps that were once common at higher latitudes. Fedexia was an early example of adaptation to the changing climate. It is possible that terrestrial trematopids existed for a few million years prior to Fedexia, Actiobates, and Anconastes. Earlier trematopids may have inhabited upland regions, and would have later immigrated to lowland and coastal regions as the climate continued to change. Some 20 million years after the appearance of Fedexia, during the Permian period, trematopids and other terrestrial vertebrates experienced rapid diversification.
Американские палеонтологи сообщили об обнаружении нового вида амфибий, живших 300 миллионов лет назад, в самом конце каменноугольного периода. Амфибию назвали Fedexia striegeli. Родовое название - Fedexia – она получила в честь американской фирмы FedEx, на землях которой был найден окаменевший череп животного. А видовое название – striegeli – амфибии дали в честь автора находки – студента Питтсбургского университета (University of Pittsburgh) Адама Стрейгеля (Adam Striegel).
В 2004 году студенты Питтсбургского университета проходили геологическую практику – они собрали окаменевшие растения в окрестностях местного аэропорта. Открытие могло и не состоятся, так как студент, обнаруживший череп древнего животного, принял выступавшие из камня зубы за фрагмент листа папоротника и уже хотел выбросить – лист показался ему мелким и неинтересным. Но в последний момент он передумал и показал находку своему преподавателю, Чарльзу Джонсу (Charles Jones) который сразу понял, что перед ним вовсе не растение, а череп древнего животного. Он передал находку палеонтологу Дэвиду Берману (David S. Berman) из Музея естественной истории Карнеги (Carnegie Museum of Natural History). Палеонтологи освободили череп от породы, изучили и недавно опубликовали статью, посвященную открытию новой амфибии, в издании Annals of Carnegie Museum.
Амфибия Fedexia striegeli относилась к семейству трематопид (Trematopidae) из отряда темноспондилов (Temnospondyli). Трематопиды были небольшими сухопутными амфибиями, которые вели хищный образ жизни и в воду, скорее всего, возвращались только для откладывания икры, а большую часть жизни проводили на суше. Они появились в конце каменноугольного периода, когда климат стал более засушливым и широко распространились в следующем, пермском периоде. Fedexia striegeli по образу жизни не отличалась от других трематопид. Она охотилась на насекомых или мелких амфибий в лесах по берегам рек и озер. Длина ее черепа была чуть больше 11 сантиметров. Другие кости скелета найти не удалось, но по аналогии с ее ближайшими родственниками палеонтологи предполагают, что общая длина федексии составляла 50-60 сантиметров. Она жила 300 миллионов лет назад, в гжельском веке поздней пенсильванской эпохи, в самом конце каменноугольного периода.
Череп федексии сохранился очень хорошо. Он не был раздавлен или разбит на куски, как это часто бывает с черепами древних животных, а сохранился целиком, позволив ученым исследовать мельчайшие детали его строения.
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Tags: Вымершие амфибии, Карбон, Лабиринтодонты, Темноспондилы
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08:29 pm [industrialterro]
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Greererpeton
Greererpeton is an extinct genus of tetrapods from the Early Carboniferous period (late Visean) of North America.
Greererpeton had an elongated body adapted for swimming, reaching up to 1.5 metres (4.9 ft) in length, including the tail. Its body had 40 vertebrae, twice the usual amount, and a flattened skull about 18 centimetres (7.1 in) long. The limbs were short, and mainly used for steering, with the long tail providing the main propulsive force while swimming.
Some marks on the side of the skull indicate that Greererpeton had a lateral line, a sensory organ commonly found only in fish. Its ears were also poorly developed. Taken together, these are indications that Greererpeton was a primitive amphibian that had returned to an almost wholly aquatic existence, rarely, if ever, venturing onto dry land.
Greererpeton was a carnivore and probably lived in rivers and swamps.
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Tags: Вымершие амфибии, Ихтиостегалии, Карбон, Лабиринтодонты
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08:39 pm [industrialterro]
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Microbrachis
Microbrachis ('small arm') is an extinct genus of lepospondyl amphibian from the Carboniferous period of what is now the Czech Republic.
Microbrachis was an elongated, salamander-like creature, about 15 centimetres (6 in) long, with over 40 vertebrae instead of the average 15-26 in its living relatives. It had minute limbs, and probably swam using fish-like lateral body movements. Microbrachis probably fed on fresh water plankton such as shrimp. Microbrachis was pedomorphic, retaining its larval gills in adulthood. Similar traits are found in the extant axolotl.
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Tags: Вымершие амфибии, Карбон, Лабиринтодонты, Лепоспондилы
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08:50 pm [industrialterro]
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Oestocephalus
Oestocephalus is an extinct genus of aïstopod lepospondyl that lived during the Carboniferous period. Fossils have been found from the Czech Republic as well as Ohio and Illinois in the United States. It is the type genus of the family Oestocephalidae, although it was previously assigned to the family Ophiderpetontidae, which is now considered paraphyletic. It was first named by Edward Drinker Cope in 1868 and now contains two species, O. amphiuminus and O. nanum.
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Tags: Вымершие амфибии, Карбон, Лабиринтодонты, Лепоспондилы
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08:54 pm [industrialterro]
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Ophiderpeton
Ophiderpeton is an extinct genus of lepospondyl amphibian from the Carboniferous period. Remains of this genus are widespread and were found in Ohio, USA and the Czech Republic (Central Europe).
An aïstopod, Ophiderpeton was snake-like, without any trace of limbs. Its body was about 70 centimetres (28 in) long, with 230 vertebrae. The skull measured 15 centimetres (5.9 in), and large, forward-facing eyes. It probably lived in burrows, feeding on insects, worms, millipedes, and snails.
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Tags: Вымершие амфибии, Карбон, Лабиринтодонты, Лепоспондилы
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09:05 pm [industrialterro]
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Proterogyrinus
Протерогиринус (лат. Proterogyrinus) — примитивный рептилиеморф (антракозавр-эмболомер) каменноугольной эпохи. Полуводный хищник, с короткими, но мощными пятипалыми конечностями. Крупная, слегка сжатая с боков голова, относительно короткое тело, мощный плоский хвост. В целом животное напоминало небольшого крокодила или крупную ящерицу. Череп кинетический, как у кистеперых рыб (подвижность частей черепа друг относительно друга позволяла шире открывать пасть). Крупные «клыки» на небе. Барабанной перепонки, по-видимому, нет (стремя очень массивное), хотя на крыше черепа сзади есть вырезки, в которых могли быть брызгальца. Сохранены каналы боковой линии на черепе. Длина тела доходила до 1,5-2 метров. Описан А. Ромером в 1970 г. Два вида — P. scheelei (типовой вид) из Грира в Западной Виргинии и P. pancheni из Лота в Шотландии. Возраст — ранний карбон (серпуховская эпоха).
Протерогиринус выделяется в особое семейство антракозавров — Proterogyrinidae, к которому может относиться и верхнедевонский тулерпетон.
During the Late Carboniferous period (326 - 318 million years ago), the amphibians were an exciting and diverse group of animals that had come to dominate the waterlogged forest world. They also were evolving into reptiles, which produced the unique and interesting reptiliomorphs.
Proterogyrinus was one of the largest of its region, and was perfectly adapted for life in the swamps. It was a top predator that hunted both on land and in the water. Its powerful jaws had sharp teeth that could handle animals that were quite large, such as fish, large arthropods, and other reptiles and amphibians.
Proterogyrinus was similar in shape to other prehistoric amphibians, and reptiliomorphs, such as Crassigyrinus and Eryops. It was about two and a half meters (7–8 feet) long, similar in size to the biggest modern lizards.
Most Carboniferous amphibians were good swimmers and could move fast through the rivers, lakes, and bogs surrounding the lowland forests, but also could walk on land like some amphibians today. Many species either stayed in the water at all times or could only wriggle through the mud on the banks; reptiliomorphs (including Proterogyrinus) ventured further into the forest. Being able to hunt away from the water's edge meant that Proterogyrinus could catch food in places where its rivals could not go. It also meant that it could escape water-borne enemies, such as predatory fish, by clambering on shore, or over the logs and other obstacles that frequently choked the swamps' river channels.
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Tags: Антракозавры, Вымершие амфибии, Карбон, Лабиринтодонты
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