Reptile - Wikipedia. Reptiles are tetrapod (four- limbed vertebrate) animals in the class. Reptilia, comprising today's turtles, crocodilians, snakes, amphisbaenians, lizards, tuatara, and their extinct relatives. The study of these traditional reptile orders, historically combined with that of modern amphibians, is called herpetology. Because some reptiles are more closely related to birds than they are to other reptiles (e.

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For this reason, many modern scientists prefer to consider the birds part of Reptilia as well, thereby making Reptilia a monophyletic class. Peak Pro 7 Download Cracked Steam. 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 Cretaceous–Paleogene extinction event wiped out the pterosaurs, plesiosaurs, ornithischians, and sauropods, as well as many species of theropods (e. Tyrannosaurus, Velociraptor, Spinosaurus, Allosaurus and birds), Crocodyliformes, and squamates (e.

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. 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.

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Extant reptiles range in size from a tiny gecko, Sphaerodactylus ariasae, which can grow up to 1. Crocodylus porosus, which may reach 6 m (1. Classification. Linnaeus, working from species- poor Sweden, where the common adder and grass snake are often found hunting in water, included all reptiles and amphibians in class . This was not the only possible classification scheme: In the Hunterian lectures delivered at the Royal College of Surgeons in 1. Huxley grouped the vertebrates into mammals, sauroids, and ichthyoids (the latter containing the fishes and amphibians).

He subsequently proposed the names of Sauropsida and Ichthyopsida for the latter two groups. Goodrich to distinguish between lizards, birds, and their relatives on the one hand (Sauropsida) and mammals and their extinct relatives (Theropsida) on the other. Goodrich supported this division by the nature of the hearts and blood vessels in each group, and other features, such as the structure of the forebrain. According to Goodrich, both lineages evolved from an earlier stem group, Protosauria (. Watson observed that the first two groups diverged very early in reptilian history, so he divided Goodrich's Protosauria between them. He also reinterpreted Sauropsida and Theropsida to exclude birds and mammals, respectively. Thus his Sauropsida included Procolophonia, Eosuchia, Millerosauria, Chelonia (turtles), Squamata (lizards and snakes), Rhynchocephalia, Crocodilia, .

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The traits listed by Lydekker in 1. This classification was initiated by Henry Fairfield Osborn and elaborated and made popular by Romer's classic Vertebrate Paleontology. Ichthyosaurs were, at times, considered to have arisen independently of the other euryapsids, and given the older name Parapsida. Parapsida was later discarded as a group for the most part (ichthyosaurs being classified as incertae sedis or with Euryapsida).

However, four (or three if Euryapsida is sunk into Diapsida) subclasses remained more or less universal for non- specialist work throughout the 2. It has largely been abandoned by recent researchers: in particular, the anapsid condition has been found to occur so variably among unrelated groups that it is not now considered a useful distinction. The reptiles as historically defined are paraphyletic, since they exclude both birds and mammals. These respectively evolved from dinosaurs and from early therapsids, which were both traditionally called reptiles.

Colin Tudge wrote: Mammals are a clade, and therefore the cladists are happy to acknowledge the traditional taxon Mammalia; and birds, too, are a clade, universally ascribed to the formal taxon Aves. Mammalia and Aves are, in fact, subclades within the grand clade of the Amniota. But the traditional class Reptilia is not a clade. It is just a section of the clade Amniota: the section that is left after the Mammalia and Aves have been hived off. It cannot be defined by synapomorphies, as is the proper way. Instead, it is defined by a combination of the features it has and the features it lacks: reptiles are the amniotes that lack fur or feathers.

At best, the cladists suggest, we could say that the traditional Reptilia are 'non- avian, non- mammalian amniotes'. In 1. 98. 8, Jacques Gauthier proposed a cladistic definition of Reptilia as a monophyletic node- based crown group containing turtles, lizards and snakes, crocodilians, and birds, their common ancestor and all its descendants. Because the actual relationship of turtles to other reptiles was not yet well understood at this time, Gauthier's definition came to be considered inadequate.

The first such new definition, which attempted to adhere to the standards of the Phylo. Code, was published by Modesto and Anderson in 2. Modesto and Anderson reviewed the many previous definitions and proposed a modified definition, which they intended to retain most traditional content of the group while keeping it stable and monophyletic. They defined Reptilia as all amniotes closer to Lacerta agilis and Crocodylus niloticus than to Homo sapiens.

This stem- based definition is equivalent to the more common definition of Sauropsida, which Modesto and Anderson synonymized with Reptilia, since the latter is better known and more frequently used. Unlike most previous definitions of Reptilia, however, Modesto and Anderson's definition includes birds. Lee, in 2. 01. 3. Classically, turtles were considered to be related to the primitive anapsid reptiles. So far three turtle genomes have been sequenced. Primitive tetrapods were particularly devastated, while stem- reptiles fared better, being ecologically adapted to the drier conditions that followed. Primitive tetrapods, like modern amphibians, need to return to water to lay eggs; in contrast, amniotes, like modern reptiles – whose eggs possess a shell that allows them to be laid on land – were better adapted to the new conditions.

Amniotes acquired new niches at a faster rate than before the collapse and at a much faster rate than primitive tetrapods. They acquired new feeding strategies including herbivory and carnivory, previously only having been insectivores and piscivores. These are the . While primitive, terrestrial reptiliomorphs still existed, the synapsid amniotes evolved the first truly terrestrial megafauna (giant animals) in the form of pelycosaurs, such as Edaphosaurus and the carnivorous Dimetrodon. In the mid- Permian period, the climate became drier, resulting in a change of fauna: The pelycosaurs were replaced by the therapsids. The pareiasaurian parareptiles reached giant proportions in the late Permian, eventually disappearing at the close of the period (the turtles being possible survivors). Both groups remained lizard- like and relatively small and inconspicuous during the Permian. Mesozoic reptiles.

These were characterized by elongated hind legs and an erect pose, the early forms looking somewhat like long- legged crocodiles. The archosaurs became the dominant group during the Triassic period, though it took 3.

Permian. Since reptiles, first rauisuchians and then dinosaurs, dominated the Mesozoic era, the interval is popularly known as the . The dinosaurs also developed smaller forms, including the feather- bearing smaller theropods. In the Cretaceous period, these gave rise to the first true birds. Lepidosauromorpha contained at least one major group of the Mesozoic sea reptiles: the mosasaurs, which lived during the Cretaceous period.