Agamidae is a family of over 300 species of iguanian lizards indigenous to Africa, Australia, a few in Southern Europe. Many species are called dragons or dragon lizards. Phylogenetically, they may be sister to the Iguanidae, have a similar appearance. Agamids have well-developed, strong legs, their tails cannot be shed and regenerated like those of geckos, though a certain amount of regeneration is observed in some. Many agamid species are capable of limited change of their colours to regulate their body temperature. In some species, males are more brightly coloured than females, colours play a part in signaling and reproductive behaviours. Although agamids inhabit warm environments, ranging from hot deserts to tropical rainforests, at least one species, the mountain dragon, is found in cooler regions; this group of lizards includes some more popularly known, such as the domesticated bearded dragon, Chinese water dragon and Uromastyx species. One of the key distinguishing features of the agamids is their teeth, which are borne on the outer rim of their mouths, rather than on the inner side of their jaws.
This feature is otherwise unusual among lizards. Agamid lizards are diurnal, with good vision, include a number of arboreal species, in addition to ground- and rock-dwellers, they feed on insects and other arthropods, although some larger species may include small reptiles or mammals, nestling birds, flowers or other vegetable matter in their diets. The great majority of agamid species are oviparous. Few studies of the Agamidae have been conducted; the first comprehensive assessment was by Moody followed by a more inclusive assessment by Frost and Etheridge. Subsequent studies were based on mitochondrial DNA loci by Macey et al. and Honda et al. and by sampling across the Agamidae by Joger. Few other studies focused on clades within the family, the Agamidae have not been as well investigated as the Iguanidae; the agamids show a curious distribution. They are found over much of the Old World, including continental Africa, southern Asia, sparsely in warmer regions of Europe, they are, absent from Madagascar and the New World.
The distribution is the opposite of that of the iguanids, which are found in just these areas but absent in areas where agamids are found. A similar faunal divide is found in between the pythons. Among the Agamidae, six subfamilies are recognized: Agaminae Amphibolurinae Draconinae Hydrosaurinae Leiolepidinae Uromasticinae The chameleons of the sister family Chamaeleonidae are sometimes discussed as subfamily Chamaeleoninae and subfamily Agaminae. Agamidae at The Reptile Database
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results
A parietal eye known as a third eye or pineal eye, is a part of the epithalamus present in some animal species. The eye is photoreceptive and is associated with the pineal gland, regulating circadian rhythmicity and hormone production for thermoregulation; the parietal eye is found in the tuatara, most lizards, salamanders, certain bony fish and lampreys. It was present in their closest extinct relatives, the therapsids, it is absent in turtles and archosaurs, which includes birds and crocodilians, their extinct relatives. Saniwa, an extinct varanid lizard, had two parietal eyes, one that developed from the pineal gland and the other from the parapineal gland. Saniwa is the only known jawed vertebrate to have both a pineal and a parapineal eye, as the only other vertebrates that have both are the jawless lampreys. In most vertebrates, the pineal gland forms the parietal eye, however, in lepidosaurs, it is formed from the parapineal gland; this implies. The parietal eye is a part of the epithalamus.
It arises as an anterior evagination of the pineal organ or as a separate outgrowth of the roof of the diencephalon. In some species, it protrudes through the skull; the parietal eye uses a different biochemical method of detecting light from that of rod cells or cone cells in a normal vertebrate eye. Many of the oldest fossil vertebrates, including ostracoderms, placoderms and early tetrapods, had a socket in the skull that appears to have held a functional third eye; this socket remains as a foramen between the parietal bones in many living amphibians and reptiles, although it has vanished in birds and mammals. The third eye, where present, is always much smaller than the main paired eyes, and, in living species, it is always covered by skin, is not visible externally. Among fish, lampreys have two parietal eyes, one that developed from the parapineal gland and the other from the pineal gland; these are one behind the other in the centre of the upper surface of the braincase. Because lampreys are among the most primitive of all living vertebrates, it is possible that this was the original condition among vertebrates, may have allowed bottom-dwelling species to sense threats from above.
As shown in the accompanying figures, the parietal eye of amphibians and reptiles appears far forward in the skull. The parietal bones, in humans, make up a portion of the rear of the skull, far from the eyes. To understand this, note that the parietal bones formed a part of the skull lying between the eyes in sarcopterygians and basal amphibians, but have moved further back in higher vertebrates. In the brain of the frog, the diencephalon, from which the pineal stalk arises, appears further forward, as the cerebral hemispheres are smaller but the optic lobes are far more prominent than the human mesencephalon, part of the brain stem. In humans the optic tract and optic nerve bridge the substantial distance between eyes and diencephalon; the pineal stalk of Petromyzon elongates considerably during metamorphosis. Crustaceans have a single eye atop the head as a nauplius; the eye can not resolve more details in images. More sophisticated segmented eyes develop on sides of the head while the initial eye stays for some time.
So, it is possible to say that, at some stage of development, crustaceans have a "third eye". Some species, like the brine shrimp, retain the primary eye. Most arthropods have simple eyes, called ocelli, between their main eyes. Third eye Arthropod eye Mollusc eye Simple eye in invertebrates Vision in fish
Wikispecies is a wiki-based online project supported by the Wikimedia Foundation. Its aim is to create a comprehensive free content catalogue of all species. Jimmy Wales stated that editors are not required to fax in their degrees, but that submissions will have to pass muster with a technical audience. Wikispecies is available under the GNU Free Documentation License and CC BY-SA 3.0. Started in September 2004, with biologists across the world invited to contribute, the project had grown a framework encompassing the Linnaean taxonomy with links to Wikipedia articles on individual species by April 2005. Benedikt Mandl co-ordinated the efforts of several people who are interested in getting involved with the project and contacted potential supporters in early summer 2004. Databases were evaluated and the administrators contacted, some of them have agreed on providing their data for Wikispecies. Mandl defined two major tasks: Figure out how the contents of the data base would need to be presented—by asking experts, potential non-professional users and comparing that with existing databases Figure out how to do the software, which hardware is required and how to cover the costs—by asking experts, looking for fellow volunteers and potential sponsorsAdvantages and disadvantages were discussed by the wikimedia-I mailing list.
The board of directors of the Wikimedia Foundation voted by 4 to 0 in favor of the establishment of a Wikispecies. The project is hosted at species.wikimedia.org. It was merged to a sister project of Wikimedia Foundation on September 14, 2004. On October 10, 2006, the project exceeded 75,000 articles. On May 20, 2007, the project exceeded 100,000 articles with a total of 5,495 registered users. On September 8, 2008, the project exceeded 150,000 articles with a total of 9,224 registered users. On October 23, 2011, the project reached 300,000 articles. On June 16, 2014, the project reached 400,000 articles. On January 7, 2017, the project reached 500,000 articles. On October 30, 2018, the project reached 600,000 articles, a total of 1.12 million pages. Wikispecies comprises taxon pages, additionally pages about synonyms, taxon authorities, taxonomical publications, institutions or repositories holding type specimen. Wikispecies asks users to use images from Wikimedia Commons. Wikispecies does not allow the use of content.
All Species Foundation Catalogue of Life Encyclopedia of Life Tree of Life Web Project List of online encyclopedias The Plant List Wikispecies, The free species directory that anyone can edit Species Community Portal The Wikispecies Charter, written by Wales
Squamata is the largest order of reptiles, comprising lizards and amphisbaenians, which are collectively known as squamates or scaled reptiles. With over 10,000 species, it is the second-largest order of extant vertebrates, after the perciform fish, equal in number to the Saurischia. Members of the order are distinguished by their skins, which bear horny shields, they possess movable quadrate bones, making it possible to move the upper jaw relative to the neurocranium. This is visible in snakes, which are able to open their mouths wide to accommodate comparatively large prey. Squamata is 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, which reached lengths of over 14 m. Among other reptiles, squamates are most related to the tuatara, which superficially resembles lizards. Squamates are a monophyletic sister group to the rhynchocephalians, members of the order Rhynchocephalia; the only surviving member of Rhynchocephalia is the tuatara.
Squamata and Rhynchocephalia form the subclass Lepidosauria, the sister group to Archosauria, the clade that contains crocodiles and birds, their extinct relatives. Fossils of rhynchocephalians first appear in the Early Triassic, meaning that the lineage leading to squamates must have existed at the time. Scientists believe crown group squamates originated in the Early Jurassic based on the fossil record; the first fossils of geckos and snakes appear in the Middle Jurassic. Other groups like iguanians and varanoids appeared in the Cretaceous. Polyglyphanodontians, a distinct clade of lizards, mosasaurs, a group of predatory marine lizards that grew to enormous sizes appeared in the Cretaceous. Squamates suffered a mass extinction at the Cretaceous–Paleogene boundary, which wiped out polyglyphanodontians and many other distinct lineages; the relationships of squamates is debatable. Although many of the groups recognized on the basis of morphology are still accepted, our understanding of their relationships to each other has changed radically as a result of studying their genomes.
Iguanians were long thought to be the earliest crown group squamates based on morphological data, genetic data suggests that geckoes are the earliest crown group squamates. Iguanians are now united with anguimorphs in a clade called Toxicofera. Genetic data suggests that the various limbless groups. A study in 2018 found that Megachirella, an extinct genus of lepidosaur that lived about 240 million years ago during the Middle Triassic, was a stem-squamate, making it the oldest known squamate; the phylogenetic analysis was conducted by performing high-resolution microfocus X-ray computed tomography scans on the fossil specimen of Megachirella to gather detailed data about its anatomy. This data was compared with a phylogenetic dataset combining the morphological and molecular data of 129 extant and extinct reptilian taxa; the comparison revealed. The study found that geckos are the earliest crown group squamates not iguanians; the male members of the group Squamata have hemipenes, which are held inverted within their bodies, are everted for reproduction via erectile tissue like that in the human penis.
Only one is used at a time, some evidence indicates that males alternate use between copulations. The hemipenis has a variety of shapes, depending on the species, it bears spines or hooks, to anchor the male within the female. Some species have forked hemipenes. Due to being everted and inverted, hemipenes do not have a enclosed channel for the conduction of sperm, but rather a seminal groove that seals as the erectile tissue expands; this is 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 lizards. Snakes use a variety of tactics in acquiring mates. Ritual combat between males for the females they want to mate with includes topping, a behavior exhibited by most viperids, in which one male will twist around the vertically elevated fore body of its opponent and forcing it downward.
It is common for neck biting to occur. Parthenogenesis is a natural form of reproduction in which the growth and development of embryos occur without fertilization. Agkistrodon contortrix and Agkistrodon piscivorus can reproduce by facultative parthenogenesis; that is, they are capable of switching from a sexual mode of reproduction to an asexual mode. The type of parthenogenesis that occurs is automixis with terminal fusion, a process in which two terminal products from the same meiosis fuse to form a diploid zygote; this process leads to genome wide homozygosity, expression of deleterious recessive alleles and to developmental abnormalities. Both captive-born and wild-born A. contortrix and A. piscivorus appear to be capable of this form of parthenogenesis. Reproduction in squamate reptiles is ordinarily sexual, with males having a ZZ pair of sex determining chromosomes, females a ZW pair. However, the Colombian Rainbow boa, Epicrates maurus, can reproduce by facultative parthenogenesis resulting in production of WW female pr
China the People's Republic of China, is a country in East Asia and the world's most populous country, with a population of around 1.404 billion. Covering 9,600,000 square kilometers, it is the third- or fourth-largest country by total area. Governed by the Communist Party of China, the state exercises jurisdiction over 22 provinces, five autonomous regions, four direct-controlled municipalities, the special administrative regions of Hong Kong and Macau. China emerged as one of the world's earliest civilizations, in the fertile basin of the Yellow River in the North China Plain. For millennia, China's political system was based on hereditary monarchies, or dynasties, beginning with the semi-legendary Xia dynasty in 21st century BCE. Since China has expanded, re-unified numerous times. In the 3rd century BCE, the Qin established the first Chinese empire; the succeeding Han dynasty, which ruled from 206 BC until 220 AD, saw some of the most advanced technology at that time, including papermaking and the compass, along with agricultural and medical improvements.
The invention of gunpowder and movable type in the Tang dynasty and Northern Song completed the Four Great Inventions. Tang culture spread in Asia, as the new Silk Route brought traders to as far as Mesopotamia and Horn of Africa. Dynastic rule ended in 1912 with the Xinhai Revolution; the Chinese Civil War resulted in a division of territory in 1949, when the Communist Party of China established the People's Republic of China, a unitary one-party sovereign state on Mainland China, while the Kuomintang-led government retreated to the island of Taiwan. The political status of Taiwan remains disputed. Since the introduction of economic reforms in 1978, China's economy has been one of the world's fastest-growing with annual growth rates above 6 percent. According to the World Bank, China's GDP grew from $150 billion in 1978 to $12.24 trillion by 2017. Since 2010, China has been the world's second-largest economy by nominal GDP and since 2014, the largest economy in the world by purchasing power parity.
China is the world's largest exporter and second-largest importer of goods. China is a recognized nuclear weapons state and has the world's largest standing army and second-largest defense budget; the PRC is a permanent member of the United Nations Security Council as it replaced the ROC in 1971, as well as an active global partner of ASEAN Plus mechanism. China is a leading member of numerous formal and informal multilateral organizations, including the Shanghai Cooperation Organization, WTO, APEC, BRICS, the BCIM, the G20. In recent times, scholars have argued that it will soon be a world superpower, rivaling the United States; the word "China" has been used in English since the 16th century. It is not a word used by the Chinese themselves, it has been traced through Portuguese and Persian back to the Sanskrit word Cīna, used in ancient India."China" appears in Richard Eden's 1555 translation of the 1516 journal of the Portuguese explorer Duarte Barbosa. Barbosa's usage was derived from Persian Chīn, in turn derived from Sanskrit Cīna.
Cīna was first used including the Mahābhārata and the Laws of Manu. In 1655, Martino Martini suggested that the word China is derived from the name of the Qin dynasty. Although this derivation is still given in various sources, it is complicated by the fact that the Sanskrit word appears in pre-Qin literature; the word may have referred to a state such as Yelang. The meaning transferred to China as a whole; the origin of the Sanskrit word is still a matter of debate, according to the Oxford English Dictionary. The official name of the modern state is the "People's Republic of China"; the shorter form is "China" Zhōngguó, from zhōng and guó, a term which developed under the Western Zhou dynasty in reference to its royal demesne. It was applied to the area around Luoyi during the Eastern Zhou and to China's Central Plain before being used as an occasional synonym for the state under the Qing, it was used as a cultural concept to distinguish the Huaxia people from perceived "barbarians". The name Zhongguo is translated as "Middle Kingdom" in English.
Archaeological evidence suggests that early hominids inhabited China between 2.24 million and 250,000 years ago. The hominid fossils of Peking Man, a Homo erectus who used fire, were discovered in a cave at Zhoukoudian near Beijing; the fossilized teeth of Homo sapiens have been discovered in Fuyan Cave in Hunan. Chinese proto-writing existed in Jiahu around 7000 BCE, Damaidi around 6000 BCE, Dadiwan from 5800–5400 BCE, Banpo dating from the 5th millennium BCE; some scholars have suggested. According to Chinese tradition, the first dynasty was the Xia, which emerged around 2100 BCE; the dynasty was considered mythical by historians until scientific excavations found early Bronze Age sites at Erlitou, Henan in 1959. It remains unclear whether these sites are the remains of the Xia dynasty or of another culture from the same period; the succeeding Shang dynasty is the earliest to be confirmed by contemporary records. The Shang ruled the plain of the Yellow River in eastern China from the 17th to the 11th century BCE.
Their oracle bone script