1.
Black mamba
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The black mamba is a venomous snake endemic to parts of sub-Saharan Africa. Skin colour varies from grey to dark brown, juvenile black mambas tend to be lighter in color than adults and darken with age. It is the longest species of venomous snake indigenous to the African continent, mature specimens generally exceed 2 meters, specimens of 4.3 to 4.5 meters have been reported. Although most mamba species are tree-dwelling snakes, the black mamba is not generally arboreal and these include savannah, woodlands, rocky slopes and in some regions dense forest. It is diurnal and chiefly an ambush predator, known to prey on hyrax, bushbabies and it is also a pursuit predator, in this it resembles some other long, speedy, highly-venomous species with well-developed vision. Over suitable surfaces it is possibly the speediest species of snake, adult mambas have few natural predators. In a threat display, the mamba usually opens its inky black mouth, spreads its narrow neck-flap and it is capable of striking at considerable range and occasionally may deliver a series of bites in rapid succession. Its venom is composed of potent neurotoxins that may cause fast onset of symptoms. Despite its reputation for being formidable and highly aggressive, like most snakes, not being proximal to humans, bites from the black mamba are not frequent. The black mamba, Dendroaspis polylepis, is an elapid within the genus Dendroaspis, although it had been known to missionaries and residents, prior to 1860, by the name mamba, which was already established in the vernacular and taken from the Zulu word imamba. The first formal description was made by Albert Günther in 1864, in 1873, Wilhelm Peters described two subspecies, the nominotypical D. polylepis polylepis and also D. polylepis antinorii. However, these are no longer held to be distinct, in 1896, Boulenger combined the species as a whole with the eastern green mamba, a lumping diagnosis that remained in force until 1946, when FitzSimons split them again into separate species. The generic name, Dendroaspis, derives from Ancient Greek dendro, meaning tree, and aspis, which is understood to mean shield, via Latin aspis, it is the source of the English word asp. In ancient texts, aspis or asp often referred to the Egyptian cobra, thus, Dendroaspis literally means tree asp, reflecting the arboreal nature of most of the species within the genus. The genus was first described by the German ornithologist and herpetologist Hermann Schlegel in 1848, slowinski et al. pointed out that the relationships of the African genus Dendroaspis are problematical. However, evidence suggests that Dendroaspis, Ophiophagus, Bungarus, the specific epithet polylepis is derived from the Ancient Greek poly meaning many and lepis meaning scale. It apparently refers to the count of this species, which is higher than some other species in the genus. Dendroaspis polylepis is a large, round-bodied, slender, but powerful snake and it tapers smoothly towards the tail, and is of markedly more robust build than its distinctly gracile congeners Dendroaspis angusticeps and Dendroaspis viridis
2.
Taxonomy (biology)
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Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. The exact definition of taxonomy varies from source to source, but the core of the remains, the conception, naming. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, the broadest meaning of taxonomy is used here. The word taxonomy was introduced in 1813 by Candolle, in his Théorie élémentaire de la botanique, the term alpha taxonomy is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, ideals can, it may be said, never be completely realized. They have, however, a value of acting as permanent stimulants. Some of us please ourselves by thinking we are now groping in a beta taxonomy, turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy, thus, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is also referred to as beta taxonomy. How species should be defined in a group of organisms gives rise to practical and theoretical problems that are referred to as the species problem. The scientific work of deciding how to define species has been called microtaxonomy, by extension, macrotaxonomy is the study of groups at higher taxonomic ranks, from subgenus and above only, than species. While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, earlier works were primarily descriptive, and focused on plants that were useful in agriculture or medicine. There are a number of stages in scientific thinking. Early taxonomy was based on criteria, the so-called artificial systems. Later came systems based on a complete consideration of the characteristics of taxa, referred to as natural systems, such as those of de Jussieu, de Candolle and Bentham. The publication of Charles Darwins Origin of Species led to new ways of thinking about classification based on evolutionary relationships and this was the concept of phyletic systems, from 1883 onwards. This approach was typified by those of Eichler and Engler, the advent of molecular genetics and statistical methodology allowed the creation of the modern era of phylogenetic systems based on cladistics, rather than morphology alone. Taxonomy has been called the worlds oldest profession, and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate
3.
Animal
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Animals are multicellular, eukaryotic organisms of the kingdom Animalia. The animal kingdom emerged as a clade within Apoikozoa as the group to the choanoflagellates. Animals are motile, meaning they can move spontaneously and independently at some point in their lives and their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later in their lives. All animals are heterotrophs, they must ingest other organisms or their products for sustenance, most known animal phyla appeared in the fossil record as marine species during the Cambrian explosion, about 542 million years ago. Animals can be divided broadly into vertebrates and invertebrates, vertebrates have a backbone or spine, and amount to less than five percent of all described animal species. They include fish, amphibians, reptiles, birds and mammals, the remaining animals are the invertebrates, which lack a backbone. These include molluscs, arthropods, annelids, nematodes, flatworms, cnidarians, ctenophores, the study of animals is called zoology. The word animal comes from the Latin animalis, meaning having breath, the biological definition of the word refers to all members of the kingdom Animalia, encompassing creatures as diverse as sponges, jellyfish, insects, and humans. Aristotle divided the world between animals and plants, and this was followed by Carl Linnaeus, in the first hierarchical classification. In Linnaeuss original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then the last four have all been subsumed into a single phylum, in 1874, Ernst Haeckel divided the animal kingdom into two subkingdoms, Metazoa and Protozoa. The protozoa were later moved to the kingdom Protista, leaving only the metazoa, thus Metazoa is now considered a synonym of Animalia. Animals have several characteristics that set apart from other living things. Animals are eukaryotic and multicellular, which separates them from bacteria and they are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking cell walls. All animals are motile, if only at life stages. In most animals, embryos pass through a stage, which is a characteristic exclusive to animals. With a few exceptions, most notably the sponges and Placozoa and these include muscles, which are able to contract and control locomotion, and nerve tissues, which send and process signals
4.
Chordate
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Chordates are deuterostomes, as during the embryo development stage the anus forms before the mouth. They are also bilaterally symmetric coelomates, in the case of vertebrate chordates, the notochord is usually replaced by a vertebral column during development, and they may have body plans organized via segmentation. There are also additional extinct taxa, the Vertebrata are sometimes considered as a subgroup of the clade Craniata, consisting of chordates with a skull, the Craniata and Tunicata compose the clade Olfactores. Of the more than 65,000 living species of chordates, the worlds largest and fastest animals, the blue whale and peregrine falcon respectively, are chordates, as are humans. Fossil chordates are known from at least as early as the Cambrian explosion, Hemichordata, which includes the acorn worms, has been presented as a fourth chordate subphylum, but it now is usually treated as a separate phylum. The Hemichordata, along with the Echinodermata, form the Ambulacraria, the Chordata and Ambulacraria form the superphylum Deuterostomia, composed of the deuterostomes. Attempts to work out the relationships of the chordates have produced several hypotheses. All of the earliest chordate fossils have found in the Early Cambrian Chengjiang fauna. Because the fossil record of early chordates is poor, only molecular phylogenetics offers a prospect of dating their emergence. However, the use of molecular phylogenetics for dating evolutionary transitions is controversial and it has also proved difficult to produce a detailed classification within the living chordates. Attempts to produce family trees shows that many of the traditional classes are paraphyletic. While this has been known since the 19th century, an insistence on only monophyletic taxa has resulted in vertebrate classification being in a state of flux. Although the name Chordata is attributed to William Bateson, it was already in prevalent use by 1880, ernst Haeckel described a taxon comprising tunicates, cephalochordates, and vertebrates in 1866. Though he used the German vernacular form, it is allowed under the ICZN code because of its subsequent latinization, among the vertebrate sub-group of chordates the notochord develops into the spine, and in wholly aquatic species this helps the animal to swim by flexing its tail. In fish and other vertebrates, this develops into the spinal cord, the pharynx is the part of the throat immediately behind the mouth. In fish, the slits are modified to form gills, a muscular tail that extends backwards behind the anus. This is a groove in the wall of the pharynx. In filter-feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus and it also stores iodine, and may be a precursor of the vertebrate thyroid gland
5.
Reptile
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Reptiles are tetrapod animals in the class Reptilia, comprising todays turtles, crocodilians, snakes, amphisbaenians, lizards, tuatara, and their extinct relatives. The study of these traditional reptile orders, historically combined with that of amphibians, is called herpetology. Because some reptiles are more related to birds than they are to other reptiles. For this reason, many scientists prefer to consider the birds part of Reptilia as well. Some early examples include the lizard-like Hylonomus and Casineria, in addition to the living reptiles, there are many diverse groups that are now extinct, in some cases due to mass extinction events. In particular, the K–Pg extinction wiped out the pterosaurs, plesiosaurs, ornithischians, and sauropods, as well as species of theropods, crocodyliforms. Modern non-avian reptiles inhabit every continent with the exception of Antarctica, several living subgroups are recognized, Testudines, approximately 400 species, Sphenodontia,1 species, Squamata, over 9,600 species, Crocodilia,25 species, and Aves,10,000 species. Reptiles are tetrapod vertebrates, creatures that either have four limbs or, unlike amphibians, reptiles do not have an aquatic larval stage. As amniotes, reptile eggs are surrounded by membranes for protection and transport, many of the viviparous species feed their fetuses through various forms of placenta analogous to those of mammals, with some providing initial care for their hatchlings. In the 18th century, the reptiles were, from the outset of classification, the terms reptile and amphibian were largely interchangeable, reptile being preferred by the French. Josephus Nicolaus Laurenti was the first to use the term Reptilia for an expanded selection of reptiles. Today, the two groups are commonly treated under the same heading as herptiles. He subsequently proposed the names of Sauropsida and Ichthyopsida for the two groups. In 1866, Haeckel demonstrated that vertebrates could be divided based on their strategies, and that reptiles, birds. The terms Sauropsida and Theropsida were used again in 1916 by E. S, Goodrich to distinguish between lizards, birds, and their relatives on the one hand and mammals and their extinct relatives on the other. Goodrich supported this division by the nature of the hearts and blood vessels in each group, according to Goodrich, both lineages evolved from an earlier stem group, Protosauria in which he included some animals today considered reptile-like amphibians, as well as early reptiles. Watson observed that the first two groups diverged very early in history, so he divided Goodrichs Protosauria between them. He also reinterpreted Sauropsida and Theropsida to exclude birds and mammals, thus his Sauropsida included Procolophonia, Eosuchia, Millerosauria, Chelonia, Squamata, Rhynchocephalia, Crocodilia, thecodonts, non-avian dinosaurs, pterosaurs, ichthyosaurs, and sauropterygians
6.
Squamata
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The Squamata, or the scaled reptiles, are the largest recent order of reptiles, comprising all lizards and snakes. With over 10,000 species, it is also the second-largest order of extant vertebrates, after the perciform fish, members of the order are distinguished by their skins, which bear horny scales or shields. They also possess movable quadrate bones, making it possible to move the upper jaw relative to the neurocranium and this is particularly visible in snakes, which are able to open their mouths very wide to accommodate comparatively large prey. They are the most variably sized order of reptiles, ranging from the 16 mm dwarf gecko to the 5.21 m green anaconda and the now-extinct mosasaurs, among the other reptiles, squamates are most closely related to the tuatara, which strongly resembles lizards. Squamates are a sister group to the tuatara. The squamates and tuatara together are a group to crocodiles and birds. Fossils of the sister group, the Rhynchocephalia, appear in the Early Triassic. Also appearing in the Cretaceous are the polyglyphanodonts, a group of uncertain affinities, and the mosasaurs. At the end of the Cretaceous, squamates suffered a major extinction at the K-T boundary which wiped out polyglyphanodonts, mosasaurs, the relationships of squamates have been debated. From morphological data, the iguanians were long thought to be the most ancient branch of the tree, however, iguanians are now united with snakes and anguimorphs in a group called the Toxicofera. DNA also suggests that the various limbless groups- snakes, amphisbaenians, and dibamids- are unrelated, the male members of the group Squamata have hemipenes, which are usually held inverted within their bodies, and are everted for reproduction via erectile tissue like that in the human penis. Only one is used at a time, and some evidence indicates that males alternate use between copulations, the hemipenis has a variety of shapes, depending on the species. Often it bears spines or hooks, to anchor the male within the female, some species even have forked hemipenes. Due to being everted and inverted, hemipenes do not have a completely enclosed channel for the conduction of sperm and this is also the only reptile group in which both viviparous and ovoviviparous species are found, as well as the usual oviparous reptiles. Some species, such as the Komodo dragon, can reproduce asexually through parthenogenesis. There have been studies on how sexual selection manifests itself in snakes, snakes use a variety of tactics in acquiring mates. It is common for neck biting to occur while the snakes are entwined, parthenogenesis is a natural form of reproduction in which growth and development of embryos occur without fertilization. Agkistrodon contortrix and Agkistrodon piscivorus can reproduce by facultative parthenogenesis and that is, they are capable of switching from a sexual mode of reproduction to an asexual mode
7.
Eastern green mamba
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This species of mamba was first described by a Scottish surgeon and zoologist in 1849. This snake mostly inhabits the regions of southern East Africa. Adult females average approximately 2.0 metres in length, Eastern green mambas prey on birds, eggs, bats, and rodents such as mice, rats, and gerbils. They are shy and elusive snakes which are seen, making them somewhat unusual among mambas. This elusiveness is usually attributed to the green colouration which blends with its environment. Like other mambas the eastern green mamba is a venomous snake. The venom consists of neurotoxins and cardiotoxins. The toxicity of individual specimens can vary based on several factors including geographical region, age, seasonal variation, diet. Bites that produce severe envenomation can be rapidly fatal, the eastern green mamba is classified under the genus Dendroaspis of the family Elapidae. Dendroaspis angusticeps was first described by a Scottish surgeon and zoologist, the generic name, Dendroaspis, derives from Ancient Greek dendro, meaning tree, and aspis, which is understood to mean shield, but also denotes cobra or simply snake, in particular snake with hood. Via Latin aspis, it is the source of the English word asp, in ancient texts, aspis or asp often referred to the Egyptian cobra, in reference to its shield-like hood. Thus, Dendroaspis literally means tree asp, reflecting the nature of most of the species within the genus. The genus was first described by the German ornithologist and herpetologist Hermann Schlegel in 1848, slowinski et al. pointed out that the relationships of the African genus Dendroaspis are problematical. However, evidence suggests that Dendroaspis, Ophiophagus, Bungarus, in addition to being called the eastern green mamba, this species is also commonly known as the common green mamba, East African green mamba, white-mouthed mamba, or just simply the green mamba. The eastern green mamba is a large, with a slightly compressed, adult males average around 1.8 metres in total length, while females average 2.0 metres in total length. This species rarely exceeds lengths of 2.5 metres, in general, the total length is 4-4.3 times the length of the tail. The head is narrow, elongate, and coffin-shaped with a distinct canthus, when threatened or otherwise aroused in someway, this species is capable of flattening its neck area, though no real hood formed. The maxillary bone has no other solid teeth, however, a pair of long, recurved, fang-like solid teeth, followed behind by a distinct interspace and numerous small teeth are on the front of the lower jaw
8.
Venomous snake
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Venomous snakes are species of the suborder Serpentes that are capable of producing venom, which is used primarily for immobilizing prey and defense mostly via mechanical injection by fangs. Common venomous snakes include the families Elapidae, Viperidae, Atractaspididae, the toxicity of them is mainly indicated by murine LD50, while multiple factors are considered to judge their potential danger to humans. The evolutionary history of snakes can be traced back to as far as 25 million years ago. There is not a single or special group for venomous snakes which comprise species from different families. This has been interpreted to mean venom in snakes originated more than once as the result of convergent evolution, around a quarter of all snake species are identified as being venomous. Venomous snakes are said to be poisonous, but poison. Poisons must be ingested, inhaled or absorbed, while venom must be injected into the body by mechanical means and it is, for example, harmless to drink snake venom as long as there are no lacerations inside the mouth or digestive tract. This ability to sequester toxins and store them for defense renders these certain snakes both poisonous and venomous, LD50, mostly on rodents, is a common indicator of snakes toxicity with a smaller resultant value indicating a higher level of toxicity. There have been studies on snake venom with a variability of potency estimates. There are four methods in which the LD50 test is conducted, which are injections to subcutis, vein, muscle, testing using dry venom mixed with 0. 1% bovine serum albumin in saline, gives more consistent results than just saline alone. Prominent venom expert Associate Professor Bryan Grieg Fry has clarified the error, in there, all the toxicity testing results were lumped in together, regardless of the mode of testing. As the mode can influence the number, venoms can only be compared within a mode. Belchers sea snakes actual LD50 is 0.24 mg/kg and 0.155 mg/kg, studies on mice and human cardiac cell culture shows that venom of the inland taipan, drop by drop, is the most toxic among all snakes. Toxicity of snake venom is used to gauge the extent of their danger to humans. Many venomous snakes are specialized predators whose venom may be adapted specifically to incapacitate their preferred prey, a number of other factors are also critical in determining the potential hazard of any given venomous snake to humans, including their distribution and behavior. For example, while the inland taipan is regarded as the worlds most venomous snake based on LD50 tests on Mice, it is a shy species and rarely strikes, and has not caused any known human fatalities
9.
Arboreal locomotion
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Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them, some animals may scale trees only occasionally, but others are exclusively arboreal. Furthermore, many of these principles may be applied to climbing without trees. The earliest known tetrapod with specializations that adapted it for climbing trees was Suminia, some invertebrate animals are exclusively arboreal in habitat, such as the tree snail. Arboreal habitats pose numerous mechanical challenges to animals moving in them and these challenges include moving on narrow branches, moving up and down inclines, balancing, crossing gaps, and dealing with obstructions. Moving along a narrow surface poses special difficulties to animals, additionally, foot placement is constrained by the need to make contact with the narrow branch. This narrowness severely restricts the range of movements and postures an animal can use to move, branches are frequently oriented at an angle to gravity in arboreal habitats, including being vertical, which poses special problems. As an animal moves up a branch, they must fight the force of gravity to raise their body. Conversely, as the animal descends, it must also fight gravity to control its descent and prevent falling, descent can be particularly problematic for many animals, and highly arboreal species often have specialized methods for controlling their descent. Due to the height of many branches and the disastrous consequences of a fall. On horizontal and gently sloped branches, the problem is tipping to the side due to the narrow base of support. The narrower the branch, the greater the difficulty in balancing a given animal faces, on steep and vertical branches, tipping becomes less of an issue, and pitching backwards or slipping downwards becomes the most likely failure. In this case, large-diameter branches pose a challenge, since the animal cannot place its forelimbs closer to the center of the branch than its hindlimbs. Branches are not continuous, and any arboreal animal must be able to move between gaps in the branches, or even between trees and this can be accomplished by reaching across gaps, by leaping across them or gliding between them. Arboreal habitats often contain many obstructions, both in the form of branches emerging from the one being moved on and other branches impinging on the space the animal needs to move through and these obstructions may impede locomotion, or may be used as additional contact points to enhance it. While obstructions tend to impede limbed animals, they benefit snakes by providing anchor points, arboreal organisms display many specializations for dealing with the mechanical challenges of moving through their habitats. Arboreal animals frequently have elongated limbs that help them cross gaps, reach fruit or other resources, test the firmness of support ahead, however, some species of lizard have reduced limb size that helps them avoid limb movement being obstructed by impinging branches. Many arboreal species, such as porcupines, chameleons, silky anteaters, spider monkeys
10.
Sub-Saharan Africa
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Sub-Saharan Africa is, geographically, the area of the continent of Africa that lies south of the Sahara. According to the UN, it consists of all African countries that are fully or partially located south of the Sahara and it contrasts with North Africa, whose territories are part of the League of Arab states within the Arab world. Somalia, Djibouti, Comoros and Mauritania are geographically in Sub-Saharan Africa, the Sahel is the transitional zone between the Sahara and the tropical savanna and forest-savanna mosaic to the south. The Sahara pump theory explains how flora and fauna left Africa to penetrate the Middle East, African pluvial periods are associated with a wet Sahara phase during which larger lakes and more rivers existed. Geographers historically divided the region into several distinct ethnographic sections based on each areas respective inhabitants, commentators in Arabic in the medieval period used the general term bilâd as-sûdân for the vast Sudan region, or sometimes extending from the coast of West Africa to Western Sudan. Its equivalent in Southeast Africa was Zanj, which was situated in the vicinity of the Great Lakes region. The geographers drew an explicit distinction between the Sudan region and its analogue Zanj, from the area to their extreme east on the Red Sea coast in the Horn of Africa. In modern-day Ethiopia and Eritrea was Al-Habash or Abyssinia, which was inhabited by the Habash or Abyssinians, Sub-Saharan Africa has a wide variety of climate zones or biomes. South Africa and the Democratic Republic of the Congo in particular are considered Megadiverse countries, the Sahel shoots across all of Africa at a latitude of about 10° to 15° N. Countries that include parts of the Sahara Desert proper in their territories and parts of the Sahel in their southern region include Mauritania, Mali, Niger, Chad. The Sahel has a hot semi-arid climate, South of the Sahel, there is a belt of savanna, widening to include most of South Sudan and Ethiopia in the east. The Serengeti ecosystem is located in northwestern Tanzania and extends to southwestern Kenya, the Kalahari Basin includes the Kalahari Desert surrounded by a belt of semi-desert. The Bushveld is a tropical ecoregion of Southern Africa. The Karoo is a semi-desert in western South Africa and this occurred 10 million to 5 million years ago. By 3 million years ago several australopithecine hominid species had developed throughout southern, eastern and they were tool users rather than tool manufacturers. The tools were classed as Oldowan, roughly 1.8 million years ago, Homo ergaster first appeared in the fossil record in Africa. From Homo ergaster, Homo erectus evolved 1.5 million years ago, some of the earlier representatives of this species were small-brained and used primitive stone tools, much like H. habilis. The brain later grew in size, and H. erectus eventually developed a complex stone tool technology called the Acheulean
11.
Bird
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Birds, a subgroup of Reptiles, are the last living examples of Dinosaurs. Birds live worldwide and range in size from the 5 cm bee hummingbird to the 2.75 m ostrich. They rank as the class of tetrapods with the most living species, at ten thousand. Birds are the closest living relatives of crocodilians, the fossil record indicates that birds evolved from feathered ancestors within the theropod group of saurischian dinosaurs. True birds first appeared during the Cretaceous period, around 100 million years ago, Birds, especially those in the southern continents, survived this event and then migrated to other parts of the world while diversifying during periods of global cooling. Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period, around 170 million years ago. Birds have wings which are more or less developed depending on the species, the digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds, have evolved for swimming. Many species annually migrate great distances, Birds are social, communicating with visual signals, calls, and bird songs, and participating in such social behaviours as cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of species are socially monogamous, usually for one breeding season at a time, sometimes for years. Other species have breeding systems that are polygynous or, rarely, Birds produce offspring by laying eggs which are fertilised through sexual reproduction. They are usually laid in a nest and incubated by the parents, most birds have an extended period of parental care after hatching. Some birds, such as hens, lay eggs even when not fertilised, songbirds, parrots, and other species are popular as pets. Guano is harvested for use as a fertiliser, Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry, the first classification of birds was developed by Francis Willughby and John Ray in their 1676 volume Ornithologiae. Carl Linnaeus modified that work in 1758 to devise the taxonomic classification system currently in use, Birds are categorised as the biological class Aves in Linnaean taxonomy. Phylogenetic taxonomy places Aves in the dinosaur clade Theropoda, Aves and a sister group, the clade Crocodilia, contain the only living representatives of the reptile clade Archosauria
12.
Lizard
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Lizards are a widespread group of squamate reptiles, with over 6,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic as it excludes the snakes which are also squamates, Lizards typically have four legs feet and external ears, though some are legless, while snakes lack both of these characteristics. Lizards and snakes share a movable quadrate bone, distinguishing them from the sphenodonts, Lizards form about 60% of all the species of extant non-avian reptiles. Some extinct varanids reached great size, The giant monitor Megalania is estimated to have reached up to 7 m long, vision, including color vision, is particularly well developed in most lizards. Most lizards communicate using body language, using specific postures, gestures, and movements to define territory, resolve disputes, some species of lizards also use pheromones or bright colors, such as the iridescent patches on the belly of Sceloporus. These colors are visible to predators, so are often hidden on the underside or between scales and only revealed when necessary. The particular innovation in this respect is the dewlap, a colored patch of skin on the throat. When a display is needed, a lizard can erect the hyoid bone of its throat, anoles are particularly famous for this display, with each species having specific colors, including patterns only visible under ultraviolet light, as many lizards can see UV light. Lizard tails are often a different and dramatically more vivid color than the rest of the body so as to potential predators to strike for the tail first. Many lizards, including geckos and skinks, are capable of shedding part of their tails through a process called autotomy. This is an example of the pars pro toto principle, sacrificing a part for the whole, the detached tail writhes and wiggles, creating a deceptive sense of continued struggle, distracting the predators attention from the fleeing prey animal. The lizard partially regenerates its tail over a period of weeks, a 2014 research identified 326 genes involved in the regeneration of lizard tails. The new section contains cartilage rather than bone, and the skin may be discolored compared to the rest of the body, most lizards are oviparous, though in some species the eggs are retained until the live young emerge. Parthenogenesis occurs in at least 50 species and may be more widespread in the group. Sexual selection in lizards shows evidence of mate choice, favouring males display fitness indicators. However, doubt has been raised over the age of Tikiguania because it is almost indistinguishable from modern agamid lizards, the Tikiguania remains may instead be late Tertiary or Quaternary in age, having been washed into much older Triassic sediments. Lizards are most closely related to the Rhynchocephalia, which appeared in the Late Triassic, mitochondrial phylogenetics suggest that the first lizards evolved in the late Permian. It had been thought on the basis of data that iguanid lizards diverged from other squamates very early on
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