A chordate is an animal constituting the phylum Chordata. During some period of their life cycle, chordates possess a notochord, a dorsal nerve cord, pharyngeal slits, an endostyle, a post-anal tail: these five anatomical features define this phylum. Chordates are bilaterally symmetric; the Chordata and Ambulacraria together form the superphylum Deuterostomia. Chordates are divided into three subphyla: Vertebrata. There are extinct taxa such as the Vetulicolia. Hemichordata has been presented as a fourth chordate subphylum, but now is treated as a separate phylum: hemichordates and Echinodermata form the Ambulacraria, the sister phylum of the Chordates. Of the more than 65,000 living species of chordates, about half are bony fish that are members of the superclass Osteichthyes. Chordate fossils have been found from as early as the Cambrian explosion, 541 million years ago. Cladistically, vertebrates - chordates with the notochord replaced by a vertebral column during development - are considered to be a subgroup of the clade Craniata, which consists of chordates with a skull.
The Craniata and Tunicata compose the clade Olfactores. Chordates form a phylum of animals that are defined by having at some stage in their lives all of the following anatomical features: A notochord, a stiff rod of cartilage that extends along the inside of the body. Among the vertebrate sub-group of chordates the notochord develops into the spine, in wholly aquatic species this helps the animal to swim by flexing its tail. A dorsal neural tube. In fish and other vertebrates, this develops into the spinal cord, the main communications trunk of the nervous system. Pharyngeal slits; the pharynx is the part of the throat behind the mouth. In fish, the slits are modified to form gills, but in some other chordates they are part of a filter-feeding system that extracts particles of food from the water in which the animals live. Post-anal tail. A muscular tail that extends backwards behind the anus. An endostyle; this is a groove in the ventral wall of the pharynx. In filter-feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus.
It stores iodine, may be a precursor of the vertebrate thyroid gland. There are soft constraints that separate chordates from certain other biological lineages, but are not part of the formal definition: All chordates are deuterostomes; this means. All chordates are based on a bilateral body plan. All chordates are coelomates, have a fluid filled body cavity called a coelom with a complete lining called peritoneum derived from mesoderm; the following schema is from the third edition of Vertebrate Palaeontology. The invertebrate chordate classes are from Fishes of the World. While it is structured so as to reflect evolutionary relationships, it retains the traditional ranks used in Linnaean taxonomy. Phylum Chordata †Vetulicolia? Subphylum Cephalochordata – Class Leptocardii Clade Olfactores Subphylum Tunicata – Class Ascidiacea Class Thaliacea Class Appendicularia Class Sorberacea Subphylum Vertebrata Infraphylum incertae sedis Cyclostomata Superclass'Agnatha' paraphyletic Class Myxini Class Petromyzontida or Hyperoartia Class †Conodonta Class †Myllokunmingiida Class †Pteraspidomorphi Class †Thelodonti Class †Anaspida Class †Cephalaspidomorphi Infraphylum Gnathostomata Class †Placodermi Class Chondrichthyes Class †Acanthodii Superclass Osteichthyes Class Actinopterygii Class Sarcopterygii Superclass Tetrapoda Class Amphibia Class Sauropsida Class Synapsida Craniates, one of the three subdivisions of chordates, all have distinct skulls.
They include the hagfish. Michael J. Benton commented that "craniates are characterized by their heads, just as chordates, or all deuterostomes, are by their tails". Most craniates are vertebrates; these consist of a series of bony or cartilaginous cylindrical vertebrae with neural arches that protect the spinal cord, with projections that link the vertebrae. However hagfish have incomplete braincases and no vertebrae, are therefore not regarded as vertebrates, but as members of the craniates, the group from which vertebrates are thought to have evolved; however the cladistic exclusion of hagfish from the vertebrates is controversial, as they ma
Reptiles are tetrapod animals in the class Reptilia, comprising today's turtles, snakes, lizards and their extinct relatives. The study of these traditional reptile orders combined with that of modern amphibians, is called herpetology; because some reptiles are more related to birds than they are to other reptiles, the traditional groups of "reptiles" listed above do not together constitute a monophyletic grouping or clade. For this reason, many modern scientists prefer to consider the birds part of Reptilia as well, thereby making Reptilia a monophyletic class, including all living Diapsids; the earliest known proto-reptiles originated around 312 million years ago during the Carboniferous period, having evolved from advanced reptiliomorph tetrapods that became adapted to life on dry land. Some early examples include 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 Cretaceous–Paleogene extinction event wiped out the pterosaurs, plesiosaurs and sauropods, as well as many species of theropods, including troodontids, dromaeosaurids and abelisaurids, along with many Crocodyliformes, squamates.
Modern non-avian reptiles inhabit all the continents except Antarctica, although some birds are found on the periphery of Antarctica. Several living subgroups are recognized: Testudines, 350 species. Reptiles are tetrapod vertebrates, creatures that either have four limbs or, like snakes, are descended from four-limbed ancestors. Unlike amphibians, reptiles do not have an aquatic larval stage. Most reptiles are oviparous, although several species of squamates are viviparous, as were some extinct aquatic clades – the fetus develops within the mother, contained in a placenta rather than an eggshell; as amniotes, reptile eggs are surrounded by membranes for protection and transport, which adapt them to reproduction on dry land. 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. Extant reptiles range in size from a tiny gecko, Sphaerodactylus ariasae, which can grow up to 17 mm to the saltwater crocodile, Crocodylus porosus, which can reach 6 m in length and weigh over 1,000 kg.
In the 13th century the category of reptile was recognized in Europe as consisting of a miscellany of egg-laying creatures, including "snakes, various fantastic monsters, assorted amphibians, worms", as recorded by Vincent of Beauvais in his Mirror of Nature. In the 18th century, the reptiles were, from the outset of classification, grouped with the amphibians. Linnaeus, working from species-poor Sweden, where the common adder and grass snake are found hunting in water, included all reptiles and amphibians in class "III – Amphibia" in his Systema Naturæ; the terms "reptile" and "amphibian" were interchangeable, "reptile" being preferred by the French. Josephus Nicolaus Laurenti was the first to formally use the term "Reptilia" for an expanded selection of reptiles and amphibians similar to that of Linnaeus. Today, the two groups are still treated under the same heading as herptiles, it was not until the beginning of the 19th century that it became clear that reptiles and amphibians are, in fact, quite different animals, Pierre André Latreille erected the class Batracia for the latter, dividing the tetrapods into the four familiar classes of reptiles, amphibians and mammals.
The British anatomist Thomas Henry Huxley made Latreille's definition popular and, together with Richard Owen, expanded Reptilia to include the various fossil "antediluvian monsters", including dinosaurs and the mammal-like Dicynodon he helped describe. This was not the only possible classification scheme: In the Hunterian lectures delivered at the Royal College of Surgeons in 1863, Huxley grouped the vertebrates into mammals and ichthyoids, he subsequently proposed the names of Ichthyopsida for the latter two groups. In 1866, Haeckel demonstrated that vertebrates could be divided based on their reproductive strategies, that reptiles and mammals were united by the amniotic egg; the terms "Sauropsida" and "Theropsida" were used again in 1916 by E. S. Goodrich to distinguish between lizards 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, other features, such as the structure of the forebrain.
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. In 1956, D. M. S. Watson observed that the first two groups diverged early in reptilian history, so he divided Goodrich's Protosauria between them, he reinterpreted Sauropsida and Theropsida to exclude birds and mammals, respectively. Thus his Sauropsida included Procolophonia, Millerosauria, Squamata, Rhynchocephalia
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
Argentina the Argentine Republic, is a country located in the southern half of South America. Sharing the bulk of the Southern Cone with Chile to the west, the country is bordered by Bolivia and Paraguay to the north, Brazil to the northeast and the South Atlantic Ocean to the east, the Drake Passage to the south. With a mainland area of 2,780,400 km2, Argentina is the eighth-largest country in the world, the fourth largest in the Americas, the largest Spanish-speaking nation; the sovereign state is subdivided into twenty-three provinces and one autonomous city, Buenos Aires, the federal capital of the nation as decided by Congress. The provinces and the capital exist under a federal system. Argentina claims sovereignty over part of Antarctica, the Falkland Islands, South Georgia and the South Sandwich Islands; the earliest recorded human presence in modern-day Argentina dates back to the Paleolithic period. The Inca Empire expanded to the northwest of the country in Pre-Columbian times; the country has its roots in Spanish colonization of the region during the 16th century.
Argentina rose as the successor state of the Viceroyalty of the Río de la Plata, a Spanish overseas viceroyalty founded in 1776. The declaration and fight for independence was followed by an extended civil war that lasted until 1861, culminating in the country's reorganization as a federation of provinces with Buenos Aires as its capital city; the country thereafter enjoyed relative peace and stability, with several waves of European immigration radically reshaping its cultural and demographic outlook. The almost-unparalleled increase in prosperity led to Argentina becoming the seventh wealthiest nation in the world by the early 20th century. Following the Great Depression in the 1930s, Argentina descended into political instability and economic decline that pushed it back into underdevelopment, though it remained among the fifteen richest countries for several decades. Following the death of President Juan Perón in 1974, his widow, Isabel Martínez de Perón, ascended to the presidency, she was overthrown in 1976 by a U.
S.-backed coup which installed a right-wing military dictatorship. The military government persecuted and murdered numerous political critics and leftists in the Dirty War, a period of state terrorism that lasted until the election of Raúl Alfonsín as President in 1983. Several of the junta's leaders were convicted of their crimes and sentenced to imprisonment. Argentina is a prominent regional power in the Southern Cone and Latin America, retains its historic status as a middle power in international affairs. Argentina has the second largest economy in South America, the third-largest in Latin America, membership in the G-15 and G-20 major economies, it is a founding member of the United Nations, World Bank, World Trade Organization, Union of South American Nations, Community of Latin American and Caribbean States and the Organization of Ibero-American States. Despite its history of economic instability, it ranks second highest in the Human Development Index in Latin America; the description of the country by the word Argentina has been found on a Venetian map in 1536.
In English the name "Argentina" comes from the Spanish language, however the naming itself is not Spanish, but Italian. Argentina means in Italian " of silver, silver coloured" borrowed from the Old French adjective argentine " of silver" > "silver coloured" mentioned in the 12th century. The French word argentine is the feminine form of argentin and derives from argent "silver" with the suffix -in; the Italian naming "Argentina" for the country implies Terra Argentina "land of silver" or Costa Argentina "coast of silver". In Italian, the adjective or the proper noun is used in an autonomous way as a substantive and replaces it and it is said l'Argentina; the name Argentina was first given by the Venetian and Genoese navigators, such as Giovanni Caboto. In Spanish and Portuguese, the words for "silver" are plata and prata and " of silver" is said plateado and prateado. Argentina was first associated with the silver mountains legend, widespread among the first European explorers of the La Plata Basin.
The first written use of the name in Spanish can be traced to La Argentina, a 1602 poem by Martín del Barco Centenera describing the region. Although "Argentina" was in common usage by the 18th century, the country was formally named "Viceroyalty of the Río de la Plata" by the Spanish Empire, "United Provinces of the Río de la Plata" after independence; the 1826 constitution included the first use of the name "Argentine Republic" in legal documents. The name "Argentine Confederation" was commonly used and was formalized in the Argentine Constitution of 1853. In 1860 a presidential decree settled the country's name as "Argentine Republic", that year's constitutional amendment ruled all the names since 1810 as valid. In the English language the country was traditionally called "the Argentine", mimicking the typical Spanish usage la Argentina and resulting from a mistaken shortening of the fuller name'Argentine Republic'.'The Argentine' fell out of fashion during the mid-to-late 20th century, now the country is referred to as "Argentina".
In the Spanish language "Argentina" is feminine, taking the feminine article "La" as the i
An omnivore is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein and fiber, metabolize the nutrients and energy of the sources absorbed, they have the ability to incorporate food sources such as algae and bacteria into their diet. Omnivores come from diverse backgrounds that independently evolved sophisticated consumption capabilities. For instance, dogs evolved from carnivorous organisms while pigs evolved from herbivorous organisms. What this means is that physical characteristics are not reliable indicators of whether an animal has the ability to obtain energy and nutrients from both plant and animal matter. Owing to the wide range of unrelated organisms independently evolving the capability to obtain energy and nutrients from both plant and animal materials, no generalizations about the anatomical features of all omnivores can realistically be made; the variety of different animals that are classified as omnivores can be placed into further categories depending on their feeding behaviors.
Frugivores include maned orangutans. All of these animals are omnivores, yet still fall into special niches in terms of feeding behavior and preferred foods. Being omnivores gives these animals more food security in stressful times or makes possible living in less consistent environments; the word omnivore derives from the Latin omnis, vora, from vorare, having been coined by the French and adopted by the English in the 1800s. Traditionally the definition for omnivory was behavioral by means of "including both animal and vegetable tissue in the diet." In more recent times, with the advent of advanced technological capabilities in fields like gastroenterology, biologists have formulated a standardized variation of omnivore used for labeling a species' actual ability to obtain energy and nutrients from materials. This has subsequently conditioned two context specific definitions. Behavioral: This definition is used to specify if a species or individual is consuming both plant and animal materials.
Physiological: This definition is used in academia to specify species that have the capability to obtain energy and nutrients from both plant and animal matter. The taxonomic utility of omnivore's traditional and behavioral definition is limited, since the diet and phylogeny of one omnivorous species might be different from that of another: for instance, an omnivorous pig digging for roots and scavenging for fruit and carrion is taxonomically and ecologically quite distinct from an omnivorous chameleon that eats leaves and insects; the term "omnivory" is not always comprehensive because it does not deal with mineral foods such as salt licks and the consumption of plant and animal material for medical purposes which would not otherwise be consumed within non-omnivores. Though Carnivora is a taxon for species classification, no such equivalent exists for omnivores, as omnivores are widespread across multiple taxonomic clades; the Carnivora order does not include all carnivorous species, not all species within the Carnivora taxon are carnivorous.
It is common to find physiological carnivores consuming materials from plants or physiological herbivores consuming material from animals, e.g. felines eating grass and deer eating birds. From a behavioral aspect, this would make them omnivores, but from the physiological standpoint, this may be due to zoopharmacognosy. Physiologically, animals must be able to obtain both energy and nutrients from plant and animal materials to be considered omnivorous. Thus, such animals are still able to be classified as carnivores and herbivores when they are just obtaining nutrients from materials originating from sources that do not complement their classification. For instance, it is well documented that animals such as giraffes and cattle will gnaw on bones, preferably dry bones, for particular minerals and nutrients. Felines, which are regarded as obligate carnivores eat grass to regurgitate indigestibles, aid with hemoglobin production, as a laxative, it is found that animals classified as carnivorous may deliberately eat plant material.
For example, in 2013, it was considered that American alligators may be physiologically omnivorous once investigations had been conducted on why they eat fruits. It was suggested that alligators ate fruits both accidentally but deliberately."Life-history omnivores" is a specialized classification given to organisms that change their eating habits during their life cycle. Some species, such as grazing waterfowl like geese, are known to eat animal tissue at one stage of their lives, but plant matter at another; the same is true for many insects, such as beetles in the family Meloidae, which begin by eating animal tissue as larvae, but change to eating plant matter after they mature. Many mosquito species in early life eat plants or assorted detritus, but as they mature, males continue to eat plant matter and nectar whereas the females eat blood to reproduce effectively. Although cases exist of herbivores eating meat and carnivores eating plant matter, the classification "omnivore" re
Salvator is a genus of lizards that belongs to the family Teiidae. Listed alphabetically. Salvator duseni Salvator merianae – Argentine black and white tegu, Argentine giant tegu Salvator rufescens – red tegu
MacGyver the Lizard
MacGyver the Lizard is an Argentine red tegu lizard and Internet celebrity known for his intelligence, friendly personality, large jowls. MacGyver has been described as "a good ambassador of the giant lizard world" for his docile and affectionate behavior. MacGyver was hatched at Ty Park's lizard farm in Punta Gorda, Florida, on July 4, 2012, he became an Internet sensation that year when his first viral video, a montage of short clips, appeared on YouTube and received hundreds of thousands of views in the time span of a few weeks. Since the age of three weeks, he has starred in numerous videos in which he appears to come when his owners call his name, he is regularly seen eating his favorite foods: salmon, eggs and grapes, as well as cuddling with his owners. MacGyver's videos have received tens of millions of combined video views across YouTube and Instagram; as a result, he has amassed a social media following in the hundreds of thousands since first appearing on YouTube in 2012, inspired a fan art hashtag on Instagram that contains pencil sketches, watercolor paintings and various other fan-created works depicting the large red lizard.
In July 2016, a fan meetup with MacGyver was held at the San Diego Reptile Supershow. MacGyver has received international coverage from a variety of publications such as Vice Media, BuzzFeed, Business Insider, the New York Post, The Daily Telegraph, the Daily Mail, as far away as China Times and Okezone.com. On September 7, 2016, AJ+ released a two-minute video about MacGyver and his owners, receiving millions of views on Facebook. On September 11, 2016 The Post featured MacGyver for their weekly Pet Instagram Review, making him the first reptile to be featured for the segment. Oct. 9, 2013: ABC Channel 10 WPBF News Sept. 9, 2016: Right This Minute Dec. 6, 2016: KGTV 10 News In August 2016, rapper Snoop Dogg posted a remixed video of MacGyver to his Instagram account which poked fun at him and his owners. MacGyver's owners responded on Facebook, joking that “It appears that Snoop Dogg is trying to get with me for illegally downloading "Gin and Juice" over 15 years ago – talk about a grudge.”
Official website MacGyver the Lizard on Instagram MacGyver the Lizard on Facebook