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40-522: Micrixalus borealis Annandale, 1912 Occidozyga borealis (Annandale, 1912) The northern frog ( Ingerana borealis ), or the Rotung oriental frog is a species of frog in the family Dicroglossidae . It is found in Bangladesh , Bhutan , northeastern India , Tibet , Nepal , and western Myanmar . Its natural habitats are small, still waters and slow-moving waters in tropical moist forests. It

80-469: A few feed on plant matter. Frog skin has a rich microbiome which is important to their health. Frogs are extremely efficient at converting what they eat into body mass. They are an important food source for predators and part of the food web dynamics of many of the world's ecosystems . The skin is semi-permeable , making them susceptible to dehydration, so they either live in moist places or have special adaptations to deal with dry habitats. Frogs produce

120-736: A point of common ancestry. It is based on Frost et al. (2006), Heinicke et al. (2009) and Pyron and Wiens (2011). Leiopelmatidae Ascaphidae Bombinatoridae Alytidae Discoglossidae Pipidae Rhinophrynidae Scaphiopodidae Pelodytidae Pelobatidae Megophryidae Heleophrynidae Sooglossidae Nasikabatrachidae Calyptocephalellidae Myobatrachidae Limnodynastidae Ceuthomantidae Brachycephalidae Eleutherodactylidae Craugastoridae Hemiphractidae Hylidae Bufonidae Aromobatidae Dendrobatidae Leptodactylidae Allophrynidae Breeding season Seasonal breeders are distinct from opportunistic breeders , that mate whenever

160-469: A prefrontal bone, presence of a hyoid plate , a lower jaw without teeth (with the exception of Gastrotheca guentheri ) consisting of three pairs of bones (angulosplenial, dentary, and mentomeckelian, with the last pair being absent in Pipoidea ), an unsupported tongue, lymph spaces underneath the skin, and a muscle, the protractor lentis, attached to the lens of the eye . The anuran larva or tadpole has

200-466: A single central respiratory spiracle and mouthparts consisting of keratinous beaks and denticles . Frogs and toads are broadly classified into three suborders: Archaeobatrachia , which includes four families of primitive frogs; Mesobatrachia , which includes five families of more evolutionary intermediate frogs; and Neobatrachia , by far the largest group, which contains the remaining families of modern frogs, including most common species throughout

240-524: A slightly warty skin and prefers a watery habitat whereas the Panamanian golden frog ( Atelopus zeteki ) is in the toad family Bufonidae and has a smooth skin. The origin of the order name Anura —and its original spelling Anoures —is the Ancient Greek alpha privative prefix ἀν- ( an- from ἀ- before a vowel) 'without', and οὐρά ( ourá ) 'animal tail'. meaning "tailless". It refers to

280-502: A wide range of vocalisations , particularly in their breeding season , and exhibit many different kinds of complex behaviors to attract mates, to fend off predators and to generally survive. Frogs are valued as food by humans and also have many cultural roles in literature, symbolism and religion. They are also seen as environmental bellwethers , with declines in frog populations often viewed as early warning signs of environmental damage. Frog populations have declined significantly since

320-576: Is known from the Early Triassic of Madagascar (250   million years ago ), but molecular clock dating suggests their split from other amphibians may extend further back to the Permian , 265   million years ago. Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforest . Frogs account for around 88% of extant amphibian species. They are also one of

360-414: Is not always true, however, both because of the importance of other factors and the invalidation of this generalization. For example, in species reproducing at high latitudes, food availability before breeding is more important than availability during reproduction itself. Other factors can also be responsible. For example, species that are preyed upon frequently may time reproduction to occur out of sync with

400-524: 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 eight 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

440-478: Is threatened by pollution due to agrochemicals but also by habitat loss and degradation. This Dicroglossidae -related article is a stub . You can help Misplaced Pages by expanding it . Frog See text A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (coming from the Ancient Greek ἀνούρα , literally 'without tail'). The oldest fossil "proto-frog" Triadobatrachus

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480-647: Is uncertain, but agrees with arguments that it could plausibly derive from a Proto-Indo-European base along the lines of * preu , meaning 'jump'. How Old English frosc gave rise to frogga is, however, uncertain, as the development does not involve a regular sound-change . Instead, it seems that there was a trend in Old English to coin nicknames for animals ending in - g , with examples—themselves all of uncertain etymology—including dog , hog , pig, stag , and (ear)wig . Frog appears to have been adapted from frosc as part of this trend. Meanwhile,

520-530: The Antarctic Peninsula , indicating that this region was once home to frogs related to those now living in South American Nothofagus forest . A cladogram showing the relationships of the different families of frogs in the clade Anura can be seen in the table below. This diagram, in the form of a tree , shows how each frog family is related to other families, with each node representing

560-719: The Cretaceous–Paleogene extinction event associated with the Chicxulub impactor . All origins of arboreality (e.g. in Hyloidea and Natatanura) follow from that time and the resurgence of forest that occurred afterwards. Frog fossils have been found on all of the Earth's continents. In 2020, it was announced that 40 million year old helmeted frog fossils had been discovered by a team of vertebrate palaeontologists in Seymour Island on

600-548: 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

640-519: The divergence of the three groups took place in the Paleozoic or early Mesozoic before the break-up 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

680-623: The edible frog ( Pelophylax esculentus ) is a hybrid between the pool frog ( P. lessonae ) and the marsh frog ( P. ridibundus ). The fire-bellied toads Bombina bombina and B. variegata are similar in forming hybrids. These are less fertile than their parents, giving rise to a hybrid zone where the hybrids are prevalent. 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

720-403: The gonadotropins LH and FSH , both pituitary hormones critical for reproductive function and behavior, into the bloodstream. Changes in gonadotropin secretion initiate the end of anestrus in females. Seasonal breeding readiness is strongly regulated by length of day ( photoperiod ) and thus season. Photoperiod likely affects the seasonal breeder through changes in melatonin secretion by

760-425: 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. Tadpoles of N. degiustoi constitute the oldest tadpoles found as of 2024, dating back to 168-161 million years ago. These tadpoles also showed adaptations for filter-feeding , implying residence in temporary pools by filter-feeding larvae

800-402: The pineal gland that ultimately alter GnRH release by the hypothalamus. Hence, seasonal breeders can be divided into groups based on fertility period. "Long day" breeders cycle when days get longer (spring) and are in anestrus in fall and winter. Some animals that are long day breeders include ring-tailed lemurs , horses , hamsters , groundhogs , and mink . "Short day" breeders cycle when

840-429: The richest in species . The Anura include all modern frogs and any fossil species that fit within the anuran definition. The characteristics of anuran adults include: 9 or fewer presacral vertebrae, the presence of a urostyle formed of fused vertebrae, no tail, a long and forward-sloping ilium, shorter fore limbs than hind limbs, radius and ulna fused, tibia and fibula fused, elongated ankle bones , absence of

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880-540: 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

920-412: The 1950s. More than one third of species are considered to be threatened with extinction and over 120 are believed to have become extinct since the 1980s. The number of malformations among frogs is on the rise and an emerging fungal disease, chytridiomycosis , has spread around the world. Conservation biologists are working to understand the causes of these problems and to resolve them. The use of

960-519: 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

1000-540: The common names frog and toad has no taxonomic justification. From a classification perspective, all members of the order Anura are frogs, but only members of the family Bufonidae are considered "true toads". The use of the term frog in common names usually refers to species that are aquatic or semi-aquatic and have smooth, moist skins; the term toad generally refers to species that are terrestrial with dry, warty skins. There are numerous exceptions to this rule. The European fire-bellied toad ( Bombina bombina ) has

1040-406: The conditions of their environment become favorable, and continuous breeders that mate year-round. The breeding season is when seasonal breeders reproduce. Various variables can affect when it occurs. A primary influence on the timing of reproduction is food availability. Organisms generally time especially stressing events of reproduction to occur in sync with increases in food availability. This

1080-474: 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

1120-782: The five most diverse vertebrate orders. Warty frog species tend to be called toads , but the distinction between frogs and toads is informal, not from taxonomy or evolutionary history. An adult frog has a stout body, protruding eyes , anteriorly-attached tongue , limbs folded underneath, and no tail (the tail of tailed frogs is an extension of the male cloaca). Frogs have glandular skin, with secretions ranging from distasteful to toxic. Their skin varies in colour from well- camouflaged dappled brown, grey and green to vivid patterns of bright red or yellow and black to show toxicity and ward off predators . Adult frogs live in fresh water and on dry land; some species are adapted for living underground or in trees. Frogs typically lay their eggs in

1160-518: 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. A 2019 study has noted the presence of Salientia from the Chinle Formation , and suggested that anurans might have first appeared during the Late Triassic . On the basis of fossil evidence, the earliest known "true frogs" that fall into

1200-477: 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. In 2008, Gerobatrachus hottoni , a temnospondyl with many frog- and salamander-like characteristics, was discovered in Texas . It dated back 290 million years and

1240-474: The length of daylight shortens (fall) and are in anestrus in spring and summer. The decreased light during the fall decreases the firing of the retinal nerves, in turn decreasing the excitation of the superior cervical ganglion, which then decreases the inhibition of the pineal gland, finally resulting in an increase in melatonin . This increase in melatonin results in an increase in GnRH and subsequently an increase in

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1280-478: The nineteenth century, and is paralleled widely in other Germanic languages , with examples in the modern languages including German Frosch , Norwegian frosk , Icelandic froskur , and Dutch (kik)vors . These words allow reconstruction of a Common Germanic ancestor * froskaz . The third edition of the Oxford English Dictionary finds that the etymology of * froskaz

1320-414: The peak in density of predators. The hypothalamus is considered to be the central control for reproduction due to its role in hormone regulation. Hence, factors that determine when a seasonal breeder will be ready for mating affect this tissue. This is achieved specifically through changes in the production of the hormone GnRH . GnRH in turn transits to the pituitary where it promotes the secretion of

1360-533: The tailless character of these amphibians. The origins of the word frog are uncertain and debated. The word is first attested in Old English as frogga , but the usual Old English word for the frog was frosc (with variants such as frox and forsc ), and it is agreed that the word frog is somehow related to this. Old English frosc remained in dialectal use in English as frosh and frosk into

1400-428: 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 + 1 ⁄ 4  in) from snout to vent. Notobatrachus degiustoi from

1440-467: The water. The eggs hatch into aquatic larvae called tadpoles that have tails and internal gills . They have highly specialised rasping mouth parts suitable for herbivorous , omnivorous or planktivorous diets. The life cycle is completed when they metamorphose into adults. A few species deposit eggs on land or bypass the tadpole stage. Adult frogs generally have a carnivorous diet consisting of small invertebrates , but omnivorous species exist and

1480-543: The word toad , first attested as Old English tādige , is unique to English and is likewise of uncertain etymology. It is the basis for the word tadpole , first attested as Middle English taddepol , apparently meaning 'toad-head'. About 88% of amphibian species are classified in the order Anura. These include over 7,700 species in 59 families , of which the Hylidae (1062 spp.), Strabomantidae (807 spp.), Microhylidae (758 spp.), and Bufonidae (657 spp.) are

1520-438: The world. The suborder Neobatrachia is further divided into the two superfamilies Hyloidea and Ranoidea . This classification is based on such morphological features as the number of vertebrae, the structure of the pectoral girdle , and the morphology of tadpoles. While this classification is largely accepted, relationships among families of frogs are still debated. Some species of anurans hybridise readily. For instance,

1560-540: Was already commonplace. 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. According to genetic studies, the families Hyloidea , Microhylidae , and the clade Natatanura (comprising about 88% of living frogs) diversified simultaneously some 66 million years ago, soon after

1600-473: 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 salire ( salio ), "to jump")

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