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23.01.2016 17:59 - Encyclopedia Largest prehistoric animals Vol.1 Vertebrates part10 Amphibians ch.2 Reptiliomorphs.Diadectids and Frogs
Автор: valentint Категория: Забавление   
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Anthracosauria
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1. Pteroplax 2. Archeria 3. Pholiderpeton 4. Anthracosaurus 5. Diplovertebron
Anthracosauria is an order of extinct reptile-like amphibians (in the broad sense) that flourished during the Carboniferous and early Permian periods, although precisely which species are included depends on one"s definition of the taxon. "Anthracosauria" is sometimes used to refer to all tetrapods more closely related to amniotes such as reptiles, mammals, and birds, rather than lissamphibians such as frogs and salamanders.
During the Carboniferous and Permian periods, some tetrapods started to evolve towards a reptilian condition. Some of these tetrapods (Archeria, Eogyrinus) were elongate, eel-like aquatic forms with diminutive limbs, while others (Seymouria, Solenodonsaurus, Diadectes, Limnoscelis) were so reptile-like that until quite recently they actually had been considered to be true reptiles, and it is likely that to a modern observer they would have appeared as large to medium-sized, heavy-set lizards. Several groups however remained aquatic or semiaquatic. Some of the chroniosuchians show the build and presumably habits of modern crocodiles and were probably also similar to crocodylians in that they were river-side predators. While some other Chroniosuchians possessed elongated newt- or eel-like bodies. The two most terrestrially adapted groups were the medium-sized insectivorous or carnivorous Seymouriamorpha and the mainly herbivorous Diadectomorpha, with many large forms. The latter group has, in most analysis, the closest relatives of the Amniotes.
Exactly where the border between reptile-like amphibians (non-amniote reptiliomorphs) and amniotes lies will probably never be known, as the reproductive structures involved fossilize poorly, but various small, advanced reptiliomorphs have been suggested as the first true amniotes, including Solenodonsaurus, Casineria and Westlothiana. Such small animals laid small eggs, 1 cm in diameter or less. Small eggs would have a small enough volume to surface ratio to be able to develop on land without the amnion and chorion actively effecting gas exchange, setting the stage for the evolution of true amniotic eggs.Although the first true amniotes probably appeared as early as the Middle Mississippian sub-epoch, non-amniote (or amphibian) reptiliomorph lineages coexisted alongside their amniote descendants for many millions of years. By the middle Permian the non-amniote terrestrial forms had died out, but several aquatic non-amniote groups continued to the end of the Permian, and in the case of the chroniosuchians survived the end Permian mass extinction, only to die out prior to the end of the Triassic.



The largest known anthracosaur was Anthracosaurus, a predator. It could reach up to 12 feet in length.
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Anthracosaurus is an extinct genus of embolomere, a close relative of reptiles that lived during the Late Carboniferous (around 310 million years ago) in what is now Scotland and England. It was a large, aquatic eel-like predator able to grow up to 3 m (10 ft) in length.It has a robust skull about 40 centimetres (1.3 ft) in length with large teeth in the jaws and on the roof of the mouth. Anthracosaurus probably inhabited swamps, rivers and lakes. Its name is Greek for "coal lizard".
Anthracosaurus is believed to have been a member of the Embolomeri, a sub group of the reptilomorphs. So far only elements of the skull are known, but if Anthracosaurus had a body similar in form to it relatives like Archeria, then the body and tail would have been long and slender and up to about three meters long. Long, slender bodies that are termed eel-like are commonly seen in carboniferous vertebrates since they allowed for easier navigation through clogged carboniferous swamps and water systems. Aside from some amphibians and reptilomorphs, xenacanthid sharks also display elongated eel-like body forms.
Anthracosaurus had long sharp teeth in its jaws, and also a second set on the roof of its mouth. These would have been used to spear and trap soft bodied prey such as fish and even other amphibians, which then would probably be swallowed whole.


Eogyrinus commonly reached 4.6 metres (15 ft), however, it was more lightly built.
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Eogyrinus attheyi (from Greek eos, meaning "dawn", and gyrinos, meaning "tadpole") was one of the largest Carboniferoustetrapods, and perhaps one of the largest of its family, Eogyrinidae, at 4.6 metres (15 ft) in length.
Eogyrinus appears to have been a powerful swimmer that moved quickly through the water by swishing its long tail from side to side. It may have been a predator, lying in wait for prey in much the same way as a modern crocodile. It was a lightly built animal, weighing around 560 kilograms (1,230 lb). Although probably better at hunting in the water, Eogyrinus could probably have also made a grab for prey passing close by on land.
Fossils of Eogyrinus are known from northern England.
Recent studies by Jennifer A. Clack suggest that the amphibianPholiderpeton described by Thomas Henry Huxley in 1869 is the same animal as Eogyrinus. If this is so, then Pholiderpeton"s name takes priority.
For the Carboniferous period Eogyrinus was a particularly large predator that had an almost eel-like body that measured out over four meters in length. This body, which featured limbs severely reduced in physical size, was an adaptation to swimming and hunting in Carboniferous swamps which would have been clogged with dense weeds, submerged plants and roots. A body with a very small frontal profile like Eogyrinus had would have had little difficultly in navigating the submerged obstacles, meaning that Eogyrinus could root out hidden prey no matter where they tried to hide.
In more modern times, Eogyrinus has been speculated to be synonymous with the genus Pholiderpeton. If this is correct then fossils attributed to Eogyrinus will have to be renamed and moved to Pholiderpeton since Pholiderpeton was named long before Eogyrinus was.


Diadectidae
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1. Orobates 2. Diadectes 3. Diasparactus 4. Westlothiana 5. Tseajaia

Diadectidae is an extinct family of early tetrapods that lived in what is now North America and Europe during the Late Carboniferous and Early Permian, and in Asia during the Late Permian. They were the first herbivorous tetrapods, and also the first fully terrestrial animals to attain large sizes. Footprints indicate that diadectids walked with an erect posture. They were the first to exploit plant material in terrestrial food chains, making their appearance an important stage in both vertebrate evolution and the development of terrestrial ecosystems.
Diadectids were some of the first tetrapods, or four-legged vertebrates, to attain large sizes. Diadectids first appear in the Late Carboniferous with the genus Desmatodon, although recently described bones from Tennessee suggest that they may have appeared even earlier in the Early Carboniferous.They underwent a small evolutionary radiation in the Late Carboniferous and Early Permian, diversifying into thirteen species and outnumbering other diadectomorphs, such as the limnoscelids. This radiation was likely the result of diadectids" expansion into a new herbivorous ecological niche that was previously unfilled.
Diadectids had a much wider geographic distribution than their relatives; while the distribution of limnoscelids is limited to parts of North America and Tseajaia is restricted to just the southwestern United States, diadectids are present in North America, Europe, and Asia.During the late Carboniferous and Permian these regions formed a single landmass called Laurasia, which comprised the northern portion of the supercontinent Pangea. For most of their evolutionary history, diadectids were likely limited to the western half of Laurasia, which is now North America and Europe. The presence of the late-surviving Alveusdectes in China suggests that diadectids radiated eastward across Laurasia. They could not have reached what is now China until the Middle Permian because, prior to that time, the Tethys Sea separated it from the rest of Laurasia. The group does not seem to have diversified to the same extent in the east as they did in the west given that no diadectids are known from Russia, which has an extensive fossil record of Early and Middle Permian tetrapod assemblages.
Diadectid extinction at the end of the early Permian allowed caseid pelycosaurs to replace them as the large herbivores; they were in turn replaced by herbivousrous therapsids (dinocephalia and anomodonts) later in the Permian.


The largest known Diacectids, Diadectes, was a heavily built animal, 1.5 to 3 meters long, with thick vertebrae and ribs.
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Diadectes (meaning crosswise-biter) is an extinct genus of large, very reptile-like amphibians that lived during the early Permian period (Cisuralian epochs, between 290 and 272 million years ago). Diadectes was one of the very first herbivorous tetrapods, and also one of the first fully terrestrial animals to attain large size.
Diadectes was a heavily built animal, 1.5 to 3 meters long, with a thick-boned skull, heavy vertebrae and ribs, massive limb girdles and short, robust limbs. The nature of the limbs and vertebrae clearly indicate a terrestrial animal.
It possesses some characteristics of reptilians and amphibians, combining a reptile-like skeleton with a more primitive, seymouriamorph-like skull. Diadectes has been classified as belonging to the sister group of the amniotes.
Among its primitive features, Diadectes has a large otic notch (a feature found in all labyrinthodonts, but not in reptiles) with an ossified tympanum. At the same time its teeth show advanced specialisations for an herbivorous diet that are not found in any other type of early Permian animal. The eight front teeth are spatulate and peg-like, and served as incisors that were used to nip off mouthfuls of vegetation. The broad, blunt cheek teeth show extensive wear associated with occlusion, and would have functioned as molars, grinding up the food. It also had a partial secondary palate, which meant it could chew its food and breathe at the same time, something many even more advanced reptiles were unable to do.
These traits are likely adaptations related to the animals" high-fiber herbivorous diet, and evolved independently of similar traits seen in some reptilian groups. Many of the reptile-like details of the post-cranial skeleton are possibly related to carrying the substantial trunk, these may be independently derived traits on Diadectes and their relatives. Though very similar, they would be anaologous rather than homologous to those of early amniotes like pelycosaurs and pareiasaurs, as the first reptiles evolved from small, swamp dwelling animals like Casineria and Westlothiana.The phenomenon of related animals evolving similarly is known as parallelophyly.
Diadectes fossil remains are known from a number of locations across North America, especially the Texas Red Beds (Wichita and Clear Fork).
Numerous species have been assigned to Diadectes, though most of those have proven to be synonyms of one another. Similarly, many supposed separate genera of diadectids have been shown to be junior synonyms of Diadectes. One of these, Nothodon, was actually published by Othniel Charles Marsh five days before the name Diadectes was published by his rival Edward Drinker Cope. Despite this fact, in 1912 Case synonymized the two names and treated Diadectes as the senior synonym, which has been followed by other paleontologists since, despite the fact that it violates the rules of biological nomenclature.


Frogs (Anura)
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1. Callobatrachus 2. Palaeobatrachus 3. Latonia 4. Thaumastosaurus 5. Rhadinosteus
A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura .The oldest fossil "proto-frog" appeared in the early Triassic of Madagascar, but molecular clock dating suggests their origins may extend further back to the Permian, 265 million years ago.
The origins and evolutionary relationships between the three main groups of amphibians are hotly debated. A molecular phylogeny based on rDNA analysis dating from 2005 suggests that salamanders and caecilians are more closely related to each other than they are to frogs and the divergence of the three groups took place in the Paleozoic or early Mesozoic before the breakup of the supercontinent Pangaea and soon after their divergence from the lobe-finned fishes. This would help account for the relative scarcity of amphibian fossils from the period before the groups split.
Another molecular phylogenetic analysis conducted about the same time concluded that lissamphibians first appeared about 330 million years ago and that the temnospondyl-origin hypothesis is more credible than other theories. The neobatrachians seemed to have originated in Africa/India, the salamanders in East Asia and the caecilians in tropical Pangaea.Other researchers, while agreeing with the main thrust of this study, questioned the choice of calibration points used to synchronise the data. They proposed that the date of lissamphibian diversification should be placed in the Permian, rather less than 300 million years ago, a date in better agreement with the palaeontological data.
A further study in 2011 using both extinct and living taxa sampled for morphological, as well as molecular data, came to the conclusion that Lissamphibia is monophyletic and that it should be nested within Lepospondyli rather than within Temnospondyli. The study postulated that Lissamphibia originated no earlier than the late Carboniferous, some 290 to 305 million years ago. The split between Anura and Caudata was estimated as taking place 292 million years ago, rather later than most molecular studies suggest, with the caecilians splitting off 239 million years ago.
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In 2008, Gerobatrachus hottoni, a temnospondyl with many frog- and salamander-like characteristics, was discovered in Texas. It dated back 290 million years and was hailed as a missing link, a stem batrachian close to the common ancestor of frogs and salamanders, consistent with the widely accepted hypothesis that frogs and salamanders are more closely related to each other (forming a clade called Batrachia) than they are to caecilians.However, others have suggested that Gerobatrachus hottoni was only a dissorophoid temnospondyl unrelated to extant amphibians.
Salientia (Latin salere , "to jump") is the name of the total group that includes modern frogs in the order Anura as well as their close fossil relatives, the "proto-frogs" or "stem-frogs". The common features possessed by these proto-frogs include 14 presacral vertebrae (modern frogs have 8 or 9), a long and forward-sloping ilium in the pelvis, the presence of a frontoparietal bone, and a lower jaw without teeth. The earliest known amphibians that were more closely related to frogs than to salamanders are Triadobatrachus massinoti, from the early Triassic period of Madagascar (about 250 million years ago), and Czatkobatrachus polonicus, from the Early Triassic of Poland (about the same age as Triadobatrachus).The skull of Triadobatrachus is frog-like, being broad with large eye sockets, but the fossil has features diverging from modern frogs. These include a longer body with more vertebrae. The tail has separate vertebrae unlike the fused urostyle or coccyx in modern frogs. The tibia and fibula bones are also separate, making it probable that Triadobatrachus was not an efficient leaper.
The earliest known "true frogs" that fall into the anuran lineage proper all lived in the early Jurassic period.One such early frog species, Prosalirus bitis, was discovered in 1995 in the Kayenta Formation of Arizona and dates back to the Early Jurassic epoch (199.6 to 175 million years ago), making Prosalirus somewhat more recent than Triadobatrachus. Like the latter, Prosalirus did not have greatly enlarged legs, but had the typical three-pronged pelvic structure of modern frogs. Unlike Triadobatrachus, Prosalirus had already lost nearly all of its tail and was well adapted for jumping.Another Early Jurassic frog is Vieraella herbsti, which is known only from dorsal and ventral impressions of a single animal and was estimated to be 33 mm (1.3 in) from snout to vent. Notobatrachus degiustoi from the middle Jurassic is slightly younger, about 155–170 million years old. The main evolutionary changes in this species involved the shortening of the body and the loss of the tail. The evolution of modern Anura likely was complete by the Jurassic period. Since then, evolutionary changes in chromosome numbers have taken place about 20 times faster in mammals than in frogs, which means speciation is occurring more rapidly in mammals.
Frog fossils have been found on all continents except Antarctica, but biogeographic evidence suggests they also inhabited Antarctica in an earlier era when the climate was warmer.


The largest known frog ever was the 16-inch-long (41 cm) Beelzebufo ampinga, weighing 10 pounds (4.5 kg)
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Beelzebufo ampinga was a particularly large species of prehistoric frog described in 2008. Common names assigned by the popular media include devil frog, devil toad, and the frog from hell.
Fossils of Beelzebufo have been recovered from strata of the Maevarano Formation in Madagascar, dating to the late Cretaceous period, some 70 million years ago (Mya).
The generic name Beelzebufo is a portmanteau of Beelzebub (a Semitic deity whose name may be translated as "Lord of the Flies", sometimes identified either as one of the chief lieutenants, or alter ego of the Christian Devil) and bufo (Latin for "toad").
The specific name ampinga means "shield" in Malagasy.
The species may have grown to 41 cm (16 in) and 4.5 kg (9.9 lb) — larger than any living frogs,including the largest known species, the goliath frog, which can be up to 32 cm (13 in). The head was big, and bones of the skull roof show a rugous external surface, indicating at least parts of the head may have borne bony scales, called scutes.
The skull sutures are open in even the biggest species of Beelzebufo, showing that it may have grown even bigger.
Although the fossils of Beelzebufo appear in what is now Madagascar, which, still attached to India, had split from the coast of Somalia in the earliest stage of the late Jurassic, it superficially resembles its closest living relatives, the horned toads of South America, of which the largest today grow to 15 cm (6 in) long.
As West Gondwana (South America) rifted away from East Gondwana, opening from the north and spreading southward, open marine conditions in the widening South Atlantic obtained by about 110 Mya, isolating the amphibians on either side; the last common ancestor of Beelzebufo and the South American Ceratophryidae is most likely to have existed before that date and probably before seafloor-spreading demonstrates the earlier isolation of Madagascar-India, a very long time undocumented by fossils.
Alternatively, the history of archaeogeography could be rewritten: Richard Lane, program director in NSF"s Division of Earth Sciences, said, "The occurrence of this frog in Madagascar and its relatives" existence in South America provides strong evidence that the supercontinent Gondwana "disassembled" during the latest part of the Cretaceous."
In comparison with the living Ceratophryidae, Beelzebufo most likely was a predator whose expansive mouth allowed it to eat relatively large prey, perhaps even juvenile dinosaurs.
The first fossil fragments were found in 1993 by David W. Krause of New York"s Stony Brook University, but it took 14 years for scientists Susan E. Evans, Marc E. H. Jones, and Krause to assemble enough data for publication in the Proceedings of the National Academy of Sciences, the journal of the United States National Academy of Sciences.
Some 75 fossil fragments have been found. Researchers have been able to reconstruct parts of the frog"s skeleton, including nearly the entire skull.












Тагове:   Mega,   size,   сова,   paleo,   prehistoric animals,   giant animals,   encyclopedia,   amphibians,   top predators,   frogs,


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