|
Zygosphene
The zygosphene-zygantrum articulation is an accessory joint between vertebrae found in several lepidosauromorph reptiles. This pivot joint consists of a forward-facing, wedge-shaped process called the zygosphene, that fits in a depression on the rearside of the next vertebrae, called the zygantrum. The zygosphene sits between the prezygapophysis in the neural arch, whereas the zygantrum sits between the postzygapophysis. This joint is found in snakes, lacertids, teiids, Gymnophthalmids as well as in some iguanids and cordylids. It is also found in several fossil groups such as plesiosaurians, nothosaurians and pachypleurosaurians. It is absent in today's Monitor lizard (''Varanus''), but occurs in fossil Varanids. The zygosphene-zygantrum joint's function is to stabilize the vertebral column. While it permits horizontal and vertical movements of the vertebral column, it prevents rotations of the single vertebrae against each other. See also * Hyposphene-hypantrum articulation, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyposphene-hypantrum Articulation
The hyposphene-hypantrum articulation is an accessory joint found in the vertebrae of several fossil reptiles of the group Archosauromorpha. It consists of a process on the backside of the vertebrae, the hyposphene, that fits in a depression in the front side of the next vertebrae, the hypantrum. Hyposphene-hypantrum articulations occur in the dorsal vertebrae and sometimes also in the posteriormost cervical and anteriormost caudal vertebrae. In most tetrapods including the human, the vertebrae are connected with each other only via the centrum and the zygapophysis joints. Additional joints like the hyposphene-hypantrum articulations, which add rigidity to the vertebral column, are found in several different reptile lineages; a known example are the zygosphene-zygantrum articulations found in snakes. Hyposphene-hypantrum articulations are found in several unrelated groups within the Archosauromorpha. They occur especially in large forms, for example in rauisuchids and in silesaur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lepidosauromorph
Lepidosauromorpha (in PhyloCode known as ''Pan-Lepidosauria'') is a group of reptiles comprising all diapsids closer to lizards than to archosaurs (which include crocodiles and birds). The only living sub-group is the Lepidosauria, which contains two subdivisions, Squamata, which contains lizards and snakes, and Rhynchocephalia, the only extant species of which is the tuatara. Lepidosauromorphs are distinguishable from archosauromorphs (reptiles closer to archosaurs) by their primitive sprawling gait (allowing for the same sinusoidal trunk and tail movement seen in fish), the sliding "joint" between the coracoids and the sternum (for a longer stride), and their pleurodont dentition. In contrast, Archosauromorphs possess a parasagittal gait, a reduction in their dermal girdle, a reduction and/or loss of the sternum, and a more thecodont dentition. Living lepidosauromorphs have retained an ectothermic (" cold blooded") metabolism, unlike the ancestral condition in archosauromorphs. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iguanidae
The Iguanidae is a family of lizards composed of the iguanas, chuckwallas, and their prehistoric relatives, including the widespread green iguana. Taxonomy Iguanidae is thought to be the sister group to the collared lizards (family Crotaphytidae); the two groups likely diverged during the Late Cretaceous, as that is when ''Pristiguana'' and ''Pariguana'', the two earliest fossil genera, are known from. The subfamily Iguaninae, which contains all modern genera, likely originated in the earliest Paleocene, at about 62 million years ago. The most basal extant genus, '' Dipsosaurus,'' diverged from the rest of Iguaninae during the late Eocene, about 38 million years ago, with '' Brachylophus'' following a few million years later at about 35 million years ago, presumably after its dispersal event to the Pacific. All other modern iguana genera formed in the Neogene period. A phylogenetic tree of Iguaninae is shown here: Description Iguanas and iguana-type species are divers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monitor Lizard
Monitor lizards are lizards in the genus ''Varanus,'' the only extant genus in the family Varanidae. They are native to Africa, Asia, and Oceania, and one species is also found in the Americas as an invasive species. About 80 species are recognized. Monitor lizards have long necks, powerful tails and claws, and well-developed limbs. The adult length of extant species ranges from in some species, to over in the case of the Komodo dragon, though the extinct varanid known as megalania (''Varanus priscus'') may have been capable of reaching lengths more than . Most monitor species are terrestrial, but arboreal and semiaquatic monitors are also known. While most monitor lizards are carnivorous, eating eggs, smaller reptiles, fish, birds, insects, and small mammals, some also eat fruit and vegetation, depending on where they live. Distribution The various species cover a vast area, occurring through Africa, the Indian subcontinent, to China, the Ryukyu Islands in southern Japan, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pachypleurosauria
left, 220px, '' Pachypleurosaurus'' Pachypleurosauria is an extinct clade of primitive sauropterygian reptiles that vaguely resembled aquatic lizards, and were limited to the Triassic period. They were elongate animals, ranging in size from , with small heads, long necks, paddle-like limbs, and long, deep tails. The limb girdles are greatly reduced, so it is unlikely these animals could move about on land. The widely spaced peg-like teeth project at the front of the jaws, indicating that these animals fed on fish. In the species ''Prosantosaurus'', it was observed that they fed on small fishes and crustaceans which they devoured entirely and that its teeth regrew after they broke off. This was the first observation of tooth replacement in a European pachypleurosaur, the only other discovery of such an event was made in China. Classification Pachypleurosaurs were originally and are often still included within the Nothosauroidea (Carroll 1988, Benton 2004). In some more recent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nothosauria
Nothosaurs (order Nothosauroidea) were Triassic marine sauropterygian reptiles that may have lived like seals of today, catching food in water but coming ashore on rocks and beaches. They averaged about in length, with a long body and tail.F. v. Huene. 1956. Paläontologie und Phylogenie der Niederen Tetrapoden aleontology and Phylogeny of the Lower Tetrapods ''VEB Gustav Fischer Verlang, Jena'' 1-716 The feet were paddle-like, and are known to have been webbed in life, to help power the animal when swimming. The neck was quite long, and the head was elongated and flattened, and relatively small in relation to the body. The margins of the long jaws were equipped with numerous sharp outward-pointing teeth, indicating a diet of fish and squid. Taxonomy The Nothosauroidea consist of two suborders: * Pachypleurosauria, small primitive forms, and * Nothosauria (including two families Nothosauridae and Simosauridae), which evolved from pachypleurosaurs. The placement of pachypleuros ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiosauria
The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic Period, possibly in the Rhaetian stage, about 203 million years ago. They became especially common during the Jurassic Period, thriving until their disappearance due to the Cretaceous–Paleogene extinction event at the end of the Cretaceous Period, about 66 million years ago. They had a worldwide oceanic distribution, and some species at least partly inhabited freshwater environments. Plesiosaurs were among the first fossil reptiles discovered. In the beginning of the nineteenth century, scientists realised how distinctive their build was and they were named as a separate order in 1835. The first plesiosaurian genus, the eponymous ''Plesiosaurus'', was named in 1821. Since then, more than a hundred vali ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cordylidae
Cordylidae is a family of small- to medium-sized lizards that occur in southern and eastern Africa. They are commonly known as girdled lizards, spinytail lizards, or girdle-tail lizards. Cordylidae is closely related to the family Gerrhosauridae, occurring in Africa and Madagascar. These two scientific families of lizards, known as Cordyliformes or Cordyloidea, are sometimes combined into a larger concept of Cordylidae. Recent molecular analyses confirm the clade made up of Cordylidae and Gerrhosauridae (Cordyloidea) and place it in a larger clade including Xantusiidae ( Cordylomorpha Vidal & Hedges, 2009).Nicolas Vidal; S. Blair HedgeThe molecular evolutionary tree of lizards, snakes, and amphisbaenians/ref> Description and behavior Girdled lizards are diurnal and insectivorous. They are terrestrial, mostly inhabiting crevices in rocky terrain, although at least one species digs burrows and another lives under exfoliating bark on trees. They have flattened heads and bodies, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gymnophthalmidae
Gymnophthalmidae is a family of lizards with at least 250 species, sometimes known commonly as spectacled lizards or microteiids. They are called "spectacled" because of their transparent lower eyelids, which allow them to still see with closed eyes. As in most lizards, except geckos, these eyelids are movable. The Alopoglossidae have been recently moved from this family. Description and ecology Spectacled lizards are related to the Teiidae, but they look like skinks (slightly more distant relatives) with smooth scales. They are generally small lizards; many species have reduced limbs. Unusually among lizards, however, it is generally the hind limbs that are reduced or absent, rather than the forelimbs. Bauer (1998). Gymnophthalmids live in a wide variety of habitats, from desert to mountain to rain forest, throughout Central America and South America. They are usually inhabitants of the forest floor or wet areas associated with tropical forests, either nocturnal or intermitten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pivot Joint
In animal anatomy, a pivot joint (trochoid joint, rotary joint or lateral ginglymus) is a type of synovial joint whose movement axis is parallel to the long axis of the proximal bone, which typically has a convex articular surface. According to one classification system, a pivot joint like the other synovial joint —the hinge joint has one degree of freedom.Platzer, Werner (2008) ''Color Atlas of Human Anatomy'', Volume 1p.28/ref> Note that the degrees of freedom of a joint is not the same as the same as joint's range of motion. Movements Pivot joints allow for rotation, which can be external (for example when rotating an arm outward), or internal (as in rotating an arm inward). When rotating the forearm, these movements are typically called pronation and supination. In the standard anatomical position, the forearms are supinated, which means that the palms are facing forward, and the thumbs are pointing away from the body. In contrast, a forearm in pronation would have the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Teiidae
Teiidae is a family of autarchoglossan lizards native to the Americas. Members of this family are generally known as whiptails or racerunners; however, tegus also belong to this family. Teiidae is sister to the Gymnopthalmidae, and both families comprise the Teiioidea. The Teiidae includes several parthenogenic species – a mode of clonal reproduction. Presently, the Teiidae consists of approximately 150 species in eighteen genera. Morphology and behavior Teiids can be distinguished from other lizards by the following characteristics: they have large rectangular scales that form distinct transverse rows ventrally and generally small granular scales dorsally, they have head scales that are separate from the skull bones, and the teiid teeth are solid at the base and "glued" to the jaw bones. Additionally, all teiids have a forked, snake-like tongue. They all possess well-developed limbs. Teiids are all terrestrial (few are semi-aquatic) and diurnal, and are primarily carnivor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacertidae
The Lacertidae are the family (biology), family of the wall lizards, true lizards, or sometimes simply lacertas, which are native to Afro-Eurasia. It is a diverse family with at least 300 species in 39 genera. They represent the dominant group of reptiles found in Europe. The group includes the genus ''Lacerta (genus), Lacerta'', which contains some of the most commonly seen lizard (thus "true" lizard) species in Europe. Habitat The European and Mediterranean species of lacertids live mainly in forest and scrubland, scrub habitats. ''Eremias'' and ''Ophisops'' species replace these in the grassland and desert habitats of Asia. African species usually live in rocky, arid areas. ''Holaspis'' species are among the few arboreal lacertids, and its two species, ''Holaspis guentheri'' and ''Holaspis laevis'', are gliders (although apparently poor ones), using their broad tail and flattened body as an aerofoil. Description Lacertids are small or medium-sized lizards. Most species are le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Lacertidae")