A paw is the soft foot-like part of a mammal a quadruped, that has claws. The paw is characterised by thin, keratinised, hairless epidermis covering subcutaneous collagenous and adipose tissue, which make up the pads; these pads act as a cushion for the load-bearing limbs of the animal. The paw consists of the large, heart-shaped metacarpal or palmar pad or metatarsal or plantar pad, four load-bearing digital pads, although there can be five or six toes in the case of domestic cats and bears. A carpal pad is found on the forelimb, used for additional traction when stopping or descending a slope in digitigrade species. Additional dewclaws can be present; the paw includes a horn-like, beak shaped claw on each digit. Though hairless, certain animals do have fur on the soles of their paws. An example is the red panda. Felids, such as cats and tigers. Bears and raccoons Weasels and other mustelids Rodents Claw Digitigrade Maine Coon Polydactyl International
Anatomical terms of motion
Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints and specific sections of the body; the terminology used describes this motion according to its direction relative to the anatomical position of the joints. Anatomists use a unified set of terms to describe most of the movements, although other, more specialized terms are necessary for describing the uniqueness of the movements such as those of the hands and eyes. In general, motion is classified according to the anatomical plane. Flexion and extension are examples of angular motions, in which two axes of a joint are brought closer together or moved further apart. Rotational motion may occur at other joints, for example the shoulder, are described as internal or external. Other terms, such as elevation and depression, describe movement above or below the horizontal plane. Many anatomical terms derive from Latin terms with the same meaning. Motions are classified after the anatomical planes they occur in, although movement is more than not a combination of different motions occurring in several planes.
Motions can be split into categories relating to the nature of the joints involved: Gliding motions occur between flat surfaces, such as in the intervertebral discs or between the carpal and metacarpal bones of the hand. Angular motions occur over synovial joints and causes them to either increase or decrease angles between bones. Rotational motions move a structure in a rotational motion along a longitudinal axis, such as turning the head to look to either side. Apart from this motions can be divided into: Linear motions, which move in a line between two points. Rectilinear motion is motion in a straight line between two points, whereas curvilinear motion is motion following a curved path. Angular motions occur when an object is around another object decreasing the angle; the different parts of the object do not move the same distance. Examples include a movement of the knee, where the lower leg changes angle compared to the femur, or movements of the ankle; the study of movement is known as kinesiology.
A categoric list of movements of the human body and the muscles involved can be found at list of movements of the human body. The prefix hyper- is sometimes added to describe movement beyond the normal limits, such as in hypermobility, hyperflexion or hyperextension; the range of motion describes the total range of motion. For example, if a part of the body such as a joint is overstretched or "bent backwards" because of exaggerated extension motion it can be described as hyperextended. Hyperextension increases the stress on the ligaments of a joint, is not always because of a voluntary movement, it may be other causes of trauma. It may be used in surgery, such as in temporarily dislocating joints for surgical procedures; these are general terms. Most terms have a clear opposite, so are treated in pairs. Flexion and extension describe movements; these terms come from the Latin words with the same meaning. Flexion describes a bending movement that decreases the angle between a segment and its proximal segment.
For example, bending the elbow, or clenching a hand into a fist, are examples of flexion. When sitting down, the knees are flexed; when a joint can move forward and backward, such as the neck and trunk, flexion refers to movement in the anterior direction. When the chin is against the chest, the head is flexed, the trunk is flexed when a person leans forward. Flexion of the shoulder or hip refers to movement of the leg forward. Extension is the opposite of flexion, describing a straightening movement that increases the angle between body parts. For example, when standing up, the knees are extended; when a joint can move forward and backward, such as the neck and trunk, extension refers to movement in the posterior direction. Extension of the hip or shoulder moves the leg backward. Abduction is the motion of a structure away from the midline while adduction refer to motion towards the center of the body; the centre of the body is defined as the midsagittal plane. These terms come from Latin words with similar meanings, ab- being the Latin prefix indicating "away," ad- indicating "toward," and ducere meaning "to draw or pull".
Abduction refers to a motion that pulls a part away from the midline of the body. In the case of fingers and toes, it refers to spreading the digits apart, away from the centerline of the hand or foot. Abduction of the wrist is called radial deviation. For example, raising the arms up, such as when tightrope-walking, is an example of abduction at the shoulder; when the legs are splayed at the hip, such as when doing a star jump or doing a split, the legs are abducted at the hip. Adduction refers to a motion that pulls a structure or part toward the midline of the body, or towards the midline of a limb. In the case of fingers and toes, it refers to bringing the digits together, towards the centerline of the hand or foot. Adduction of the wrist is called ulnar deviation. Dropping the arms to the sides, bringing the knees together, are examples of adduction. Ulnar deviation is the hand moving towards the ulnar styloid. Radial deviation is the hand moving towards the radial styloid; the terms elevation and depression refer to movement below the horizontal.
They derive from the Latin terms with similar meaningsElevation refers to movement in a superior direction. For example
The arthropod leg is a form of jointed appendage of arthropods used for walking. Many of the terms used for arthropod leg segments are of Latin origin, may be confused with terms for bones: coxa, femur, tarsus, metatarsus, dactylus, patella. Homologies of leg segments between groups are difficult to prove and are the source of much argument; some authors posit up to eleven segments per leg for the most recent common ancestor of extant arthropods but modern arthropods have eight or fewer. It has been argued that the ancestral leg need not have been so complex, that other events, such as successive loss of function of a Hox-gene, could result in parallel gains of leg segments; the appendages of arthropods may be either uniramous. A uniramous limb comprises a single series of segments attached end-to-end. A biramous limb, branches into two, each branch consists of a series of segments attached end-to-end; the external branch of the appendages of crustaceans is known as the exopod or exopodite, while the internal branch is known as the endopod or endopodite.
Other structures aside from the latter two are termed endites. Exopodites can be distinguished from exites by the possession of internal musculature; the exopodites can sometimes be missing in some crustacean groups, they are absent in insects. The legs of insects and myriapods are uniramous. In crustaceans, the first antennae are uniramous, but the second antennae are biramous, as are the legs in most species. For a time, possession of uniramous limbs was believed to be a shared, derived character, so uniramous arthropods were grouped into a taxon called Uniramia, it is now believed that several groups of arthropods evolved uniramous limbs independently from ancestors with biramous limbs, so this taxon is no longer used. Arachnid legs differ from those of insects by the addition of two segments on either side of the tibia, the patella between the femur and the tibia, the metatarsus between the tibia and the tarsus, making a total of seven segments; the situation is identical with the addition of a pre-tarsus beyond the tarsus.
The claws of the scorpion are not legs, but are pedipalps, a different kind of appendage, found in spiders and is specialised for predation and mating. In Limulus, there are no pretarsi, leaving six segments per leg; the legs of crustaceans are divided primitively into seven segments, which do not follow the naming system used in the other groups. They are: coxa, ischium, carpus and dactylus. In some groups, some of the limb segments may be fused together; the claw of a lobster or crab is formed by the articulation of the dactylus against an outgrowth of the propodus. Crustacean limbs differ in being biramous, whereas all other extant arthropods have uniramous limbs. Myriapods have seven-segmented walking legs, comprising coxa, prefemur, tibia, a tarsal claw. Myriapod legs show a variety of modifications in different groups. In all centipedes, the first pair of legs is modified into a pair of venomous fangs called forcipules. In most millipedes, one or two pairs of walking legs in adult males are modified into sperm-transferring structures called gonopods.
In some millipedes, the first leg pair in males may be reduced to tiny hooks or stubs, while in others the first pair may be enlarged. Insects and their relatives are hexapods, having six legs, connected to the thorax, each with five components. In order from the body they are the coxa, femur and tarsus; each is a single segment, except the tarsus which can be from three to seven segments, each referred to as a tarsomere. A representative insect leg, such as that of a housefly or cockroach, has the following parts, in sequence from most proximal to most distal: coxa trochanter femur tibia tarsus pretarsus. Associated with the leg itself there are various sclerites around its base, their functions are articular and have to do with how the leg attaches to the main exoskeleton of the insect. Such sclerites differ between unrelated insects; the coxa is the proximal functional base of the leg. It articulates with the pleuron and associated sclerites of its thoracic segment, in some species it articulates with the edge of the sternite as well.
The homologies of the various basal sclerites are open to debate. Some authorities suggest. In many species the coxa has two lobes; the posterior lobe is the meron, the larger part of the coxa. A meron is well developed in Periplaneta, the Isoptera and Lepidoptera; the trochanter articulates with the coxa but is attached rigidly to the femur. In some insects its appearance may be confusing. In parasitic Hymenoptera the base of the femur has the appearance of a second trochanter. In most insects the femur is the largest region of the leg; the tibia is the fourth section of the typical insect leg. As a rule the tibia of an insect is slender in comparison to the femur, but it is at least as long and longer. Near the dis
The boa constrictor called the red-tailed boa or the common boa, is a species of large, non-venomous, heavy-bodied snake, kept and bred in captivity. The boa constrictor is a member of the family Boidae, found in tropical North and South America, as well as some islands in the Caribbean. A staple of private collections and public displays, its color pattern is variable yet distinctive. Nine subspecies are recognized, although some of these are controversial; this article focuses on the species Boa constrictor as a whole, on the nominate subspecies B. c. constrictor. Though all boids are constrictors, only this species is properly referred to as a "boa constrictor" – a rare instance of an animal having the same common English name and scientific binomial name. All subspecies are referred to as "boa constrictors", while the nominate subspecies, B. c. constrictor, is referred to as the "red-tailed boa". Within the exotic pet trade, it is known as a "BCC", an abbreviation of its scientific name, to distinguish it from other boa species such as B. imperator, regularly, erroneously, referred to as a "red-tailed boa" or "common boa".
Other common names include chij-chan and macajuel. The boa constrictor is a large snake, although it is only modestly sized in comparison to other large snakes, such as the reticulated python and Burmese python, can reach lengths from 3–13 ft depending on the locality and the availability of suitable prey. Clear sexual dimorphism is seen in the species, with females being larger in both length and girth than males; the usual size of mature female boas is between 7 and 10 ft whereas males are 6 and 8 ft. Females exceed 10 ft in captivity, where lengths up to 12 ft or 14 ft can be seen; the largest documented non-stretched dry skin is deposited at Zoologische Staatssammlung München and measures 14.6 ft without head. A report of a boa constrictor growing up to 18.5 ft was found to be a misidentified green anaconda. The boa constrictor is a heavy-bodied snake, large specimens can weigh up to 27 kg. Females, the larger sex, more weigh 10 to 15 kg; some specimens of this species can reach or exceed 45 kg, although this is not usual.
The size and weight of a boa constrictor depends on subspecies and the availability of suitable prey. B. c. constrictor reaches, tops, the averages given above, as it is one of the large subspecies of Boa constrictor. Other examples of sexual dimorphism in the species include males having longer tails to contain the hemipenes and longer pelvic spurs, which are used to grip and stimulate the female during copulation. Pelvic spurs are the only external sign of the rudimentary hind legs and pelvis, seen in all boas and pythons; the coloring of boa constrictors can vary depending on the locality. However, they are a brown, grey, or cream base color, patterned with brown or reddish-brown "saddles" that become more pronounced towards the tail; this coloring gives B. c. constrictor the common name of "red-tailed boa", as it has more red saddles than other B. constrictor subspecies. The coloring works as effective camouflage in the jungles and forests of its natural range; some individuals exhibit pigmentary disorders, such as albinism.
Although these individuals are rare in the wild, they are common in captivity, where they are selectively bred to make a variety of different color "morphs". Boa constrictors have an arrow-shaped head with distinctive stripes on it: One runs dorsally from the snout to the back of the head. Boa constrictors can sense heat via cells in their lips, though they lack the labial pits surrounding these receptors seen in many members of the family Boidae. Boa constrictors have two lungs, a smaller left and an enlarged right lung to better fit their elongated shape, unlike many colubrid snakes, which have lost the left lung. Boa imperator has 81–95 dorsal scales, 231–250 ventral scales, 43–62 subcaudal scales, 21–25 supralabial scales and 2–3 anal scales. Depending on the subspecies, Boa constrictor can be found through South America north of 35°S, in the Lesser Antilles, many other islands along the coasts of South America. An introduced population exists in extreme southern Florida, a small population on St. Croix in the US Virgin Islands now appears to be reproducing in the wild.
The type locality given is "Indiis" -- a mistake, according to Orejas-Miranda. B. Constrictor flourishes in a wide variety of environmental conditions, from tropical rainforests to arid semidesert country. However, it prefers to live in rainforest due to the humidity and temperature, natural cover from predators, vast amount of potential prey, it is found in or along rivers and streams, as it is a capable swimmer. Boa constrictors occupy the burrows of medium-sized mammals, where they can hide from potential predators. Boa constrictors live on their own, do not interact with any other snakes unless they want to mate, they are nocturnal. As semi-arboreal snakes, young boa constrictors may climb into shrubs to forage.
Cassowaries, genus Casuarius, are ratites that are native to the tropical forests of New Guinea, East Nusa Tenggara, the Maluku Islands, northeastern Australia. There are three extant species; the most common of these, the southern cassowary, is the third-tallest and second-heaviest living bird, smaller only than the ostrich and emu. Cassowaries feed on fruit, although all species are omnivorous and will take a range of other plant food, including shoots and grass seeds, in addition to fungi and small vertebrates. Cassowaries are wary of humans, but if provoked they are capable of inflicting serious injuries fatal, to dogs and people; the genus Casuarius was erected by the French scientist Mathurin Jacques Brisson in his Ornithologie published in 1760. The type species is the southern cassowary; the Swedish naturalist Carl Linnaeus had introduced the genus Casuarius in the 6th edition of his Systema Naturae published in 1748, but Linnaeus dropped the genus in the important tenth edition of 1758 and put the southern cassowary together with the common ostrich and the greater rhea in the genus Struthio.
As the publication date of Linnaeus's sixth edition was before the 1758 starting point of the International Commission on Zoological Nomenclature and not Linnaeus is considered as the authority for the genus. Cassowaries are part of the ratite group, which includes the emu, rheas and kiwi, the extinct moas and elephant birds. Three extant species are recognized, one extinct: Pygmy cassowary Casuarius lydekkeri a small cassowary from the Pleistocene of New South Wales and Papua New Guinea. Most authorities consider the taxonomic classification above to be monotypic; the taxonomic name C. papuanus may be in need of revision to Casuarius westermanni. Validation of these subspecies has proven difficult due to individual variations, age-related variations, the scarcity of specimens, the stability of specimens, the practice of trading live cassowaries for thousands of years, some of which are to have escaped or been deliberately introduced to regions away from their origin; the evolutionary history of cassowaries, as of all ratites, is not well known.
A fossil species was reported from Australia, but for reasons of biogeography this assignment is not certain and it might belong to the prehistoric Emuarius, which were cassowary-like primitive emus. All cassowaries are shy birds, found in the deep forest, they are adept at disappearing. The southern cassowary of the far north Queensland rain forests is not well studied, the northern and dwarf cassowaries less so. Females are more brightly coloured. Adult southern cassowaries are 1.5 to 1.8 m tall, although some females may reach 2 m, weigh 58.5 kg. All cassowaries have feathers that consist of loose barbules, they do not have a preen gland. Cassowaries have small wings with 5–6 large remeges; these are reduced like porcupine quills, with no barbs. A claw is on each second finger; the furcula and coracoid are degenerate, their palatal bones and sphenoid bones touch each other. These, along with their wedge-shaped body, are thought to be adaptations to ward off vines and saw-edged leaves, allowing them to run through the rainforest.
Cassowaries have three-toed feet with sharp claws. The second toe, the inner one in the medial position, sports a dagger-like claw that can be 125 mm long; this claw is fearsome since cassowaries sometimes kick humans and animals with their enormously powerful legs. Cassowaries can jump up to 1.5 m. They are good swimmers, swimming in the sea. All three species have a keratinous skin-covered casque on their heads; the casque's shape and size, up to 18 cm, is species-dependent. Casuarius casuarius has the largest and Casuarius bennetti the smallest, with Casuarius unappendiculatus having variations in between. Contrary to earlier findings, the hollow inside of the casque is spanned with fine fibres which are believed to have an acoustic function. Several functions for the casque have been proposed. One is. Other suggested functions include being used to batter through underbrush, as a weapon in dominance disputes, or for pushing aside leaf litter during foraging; the latter three are disputed by biologist Andrew Mack, whose personal observation suggests that the casque amplifies deep sounds.
Earlier research indicates the birds lower their heads when running "full tilt through the vegetation, brushing saplings aside and careening into small trees. The casque would help protect the skull from such collisions". Cassowaries eat fallen fruit and spend much time under trees where seeds the size of golfballs or larger fall from heights of up to 30 m, it has been speculated that the casques play a role in either sound reception or acoustic communication. This is related to their discovery that at least the dwarf cassowary and southern cassowary produce very-low frequency sounds, which may aid in communication in dense rainforest; the "bo
Felidae is a family of mammals in the order Carnivora, colloquially referred to as cats. A member of this family is called a felid; the term "cat" refers both to felids in general and to the domestic cat. The Felidae species exhibit the most diverse fur pattern of all terrestrial carnivores. Cats have slender muscular bodies and strong flexible forelimbs, their teeth and facial muscles allow for a powerful bite. They are all obligate carnivores, most are solitary predators ambushing or stalking their prey. Wild cats occur in Africa, Europe and the Americas; some wild cat species are adapted to forest habitats, some to arid environments, a few to wetlands and mountainous terrain. Their activity patterns range from nocturnal and crepuscular to diurnal, depending on their preferred prey species. Reginald Innes Pocock divided the extant Felidae into three subfamilies: the Pantherinae, the Felinae and the Acinonychinae, differing from each other by the ossification of the hyoid apparatus and by the cutaneous sheaths which protect their claws.
This concept has been revised following developments in molecular biology and techniques for analysis of morphological data. Today, the living Felidae are divided in two subfamilies, with the Pantherinae including seven Panthera and two Neofelis species; the Felinae include all the non-pantherine cats with 34 species. The first cats emerged during the Oligocene about 25 million years ago, with the appearance of Proailurus and Pseudaelurus; the latter species complex was ancestral to two main lines of felids: the cats in the extant subfamilies and a group of extinct cats of the subfamily Machairodontinae, which include the saber-toothed cats such as the Smilodon. The "false sabre toothed cats", the Barbourofelidae and Nimravidae, are not true cats, but are related. Together with the Felidae, Viverridae and mongooses, they constitute the Feliformia. All members of the cat family have the following characteristics in common: They are digitigrade, have five toes on their forefeet and four on their hind feet.
Their curved claws are protractile and attached to the terminal bones of the toe with ligaments and tendons. The claws are guarded except in the Acinonyx, they protract the claws by contracting muscles in the toe, they passively retract them. The dewclaws do not protract, they have 30 teeth with a dental formula of 22.214.171.124.1.2.1. The upper third premolar and lower molar are adapted as carnassial teeth, suited to tearing and cutting flesh; the canine teeth are large. The lower carnassial is smaller than the upper carnassial and has a crown with two compressed blade-like pointed cusps, their nose projects beyond the lower jaw. They have well developed and sensitive whiskers above the eyes, on the cheeks, on the muzzle, but not below the chin. Whiskers help to capture and hold prey, their skull is foreshortened with large orbits. Their tongue is covered with horny papillae, which rasp meat from aid in grooming, their eyes are large, situated to provide binocular vision. Their night vision is good due to the presence of a tapetum lucidum, which reflects light back inside the eyeball, gives felid eyes their distinctive shine.
As a result, the eyes of felids are about six times more light sensitive than those of humans, many species are at least nocturnal. The retina of felids contains a high proportion of rod cells, adapted for distinguishing moving objects in conditions of dim light, which are complemented by the presence of cone cells for sensing colour during the day, their external ears are large, sensitive to high-frequency sounds in the smaller cat species. This sensitivity allows them to locate small rodent prey, they have flexible bodies with muscular limbs. The plantar pads of both fore and hind feet form compact three-lobed cushions; the penis is boneless. Relative to body size, they have shorter bacula than canids, they can not detect the sweetness of sugar. Felids have a vomeronasal organ in the roof of the mouth; the use of this organ is associated with the Flehmen response. The standard sounds made by all felids include meowing, hissing and growling. Meowing is the main contact sound, they can purr during both phases of respiration, though pantherine cats seem to purr only during oestrus and copulation, as cubs when suckling.
Purring is a low pitch sound of less than 2 kHz and mixed with other vocalization types during the expiratory phase. Most felids are able to land on their feet after a fall due to the cat righting reflex; the colour and density of their fur is diverse. Fur colour varies from light brown to golden and reddish brown, fur pattern from distinctive small spots, stripes to small blotches and rosettes. Most cat species are born except the jaguarundi, Asian golden cat and caracal; the spotted fur of lion and cougar cubs change to a uniform fur during their ontogeny. Those living in cold environments have thick fur with long hair, like the snow leopard and the Pallas's cat; those living in tropical and hot climate zones have short fur. Several species exhibit melanism with all-black individuals. In the great majority of cat species, the tail is between a third and a half of the body length, although with some exceptions, like the Ly
Amphibians are ectothermic, tetrapod vertebrates of the class Amphibia. Modern amphibians are all Lissamphibia, they inhabit a wide variety of habitats, with most species living within terrestrial, arboreal or freshwater aquatic ecosystems. Thus amphibians start out as larvae living in water, but some species have developed behavioural adaptations to bypass this; the young undergo metamorphosis from larva with gills to an adult air-breathing form with lungs. Amphibians use their skin as a secondary respiratory surface and some small terrestrial salamanders and frogs lack lungs and rely on their skin, they are superficially similar to lizards but, along with mammals and birds, reptiles are amniotes and do not require water bodies in which to breed. With their complex reproductive needs and permeable skins, amphibians are ecological indicators; the earliest amphibians evolved in the Devonian period from sarcopterygian fish with lungs and bony-limbed fins, features that were helpful in adapting to dry land.
They diversified and became dominant during the Carboniferous and Permian periods, but were displaced by reptiles and other vertebrates. Over time, amphibians shrank in size and decreased in diversity, leaving only the modern subclass Lissamphibia; the three modern orders of amphibians are Anura and Apoda. The number of known amphibian species is 8,000, of which nearly 90% are frogs; the smallest amphibian in the world is a frog from New Guinea with a length of just 7.7 mm. The largest living amphibian is the 1.8 m Chinese giant salamander, but this is dwarfed by the extinct 9 m Prionosuchus from the middle Permian of Brazil. The study of amphibians is called batrachology, while the study of both reptiles and amphibians is called herpetology; the word "amphibian" is derived from the Ancient Greek term ἀμφίβιος, which means "both kinds of life", ἀμφί meaning "of both kinds" and βιος meaning "life". The term was used as a general adjective for animals that could live on land or in water, including seals and otters.
Traditionally, the class Amphibia includes all tetrapod vertebrates. Amphibia in its widest sense was divided into three subclasses, two of which are extinct: Subclass Lepospondyli† Subclass Temnospondyli† Subclass Lissamphibia Salientia: Jurassic to present—6,200 current species in 53 families Caudata: Jurassic to present—652 current species in 9 families Gymnophiona: Jurassic to present—192 current species in 10 families The actual number of species in each group depends on the taxonomic classification followed; the two most common systems are the classification adopted by the website AmphibiaWeb, University of California and the classification by herpetologist Darrel Frost and the American Museum of Natural History, available as the online reference database "Amphibian Species of the World". The numbers of species cited above follows Frost and the total number of known amphibian species as of March 31, 2019 is 8,000, of which nearly 90% are frogs. With the phylogenetic classification, the taxon Labyrinthodontia has been discarded as it is a polyparaphyletic group without unique defining features apart from shared primitive characteristics.
Classification varies according to the preferred phylogeny of the author and whether they use a stem-based or a node-based classification. Traditionally, amphibians as a class are defined as all tetrapods with a larval stage, while the group that includes the common ancestors of all living amphibians and all their descendants is called Lissamphibia; the phylogeny of Paleozoic amphibians is uncertain, Lissamphibia may fall within extinct groups, like the Temnospondyli or the Lepospondyli, in some analyses in the amniotes. This means that advocates of phylogenetic nomenclature have removed a large number of basal Devonian and Carboniferous amphibian-type tetrapod groups that were placed in Amphibia in Linnaean taxonomy, included them elsewhere under cladistic taxonomy. If the common ancestor of amphibians and amniotes is included in Amphibia, it becomes a paraphyletic group. All modern amphibians are included in the subclass Lissamphibia, considered a clade, a group of species that have evolved from a common ancestor.
The three modern orders are Anura and Gymnophiona. It has been suggested that salamanders arose separately from a Temnospondyl-like ancestor, that caecilians are the sister group of the advanced reptiliomorph amphibians, thus of amniotes. Although the fossils of several older proto-frogs with primitive characteristics are known, the oldest "true frog" is Prosalirus bitis, from the Early Jurassic Kayenta Formation of Arizona, it is anatomically similar to modern frogs. The oldest known caecilian is another Early Jurassic species, Eocaecilia micropodia from Arizona; the earliest salamander is Beiyanerpeton jianpingensis from the Late Jurassic of northeastern China. Authorities disagree as to whether Salientia is a superorder that includes the order Anura, or whether