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Ovoo (lizard)
''Ovoo gurvel'' is an extinct varanid lizard from the Late Cretaceous of Mongolia. It is one of the smallest and earliest monitor lizards. It was described in 2008. ''Ovoo'' possesses a pair of two small bones in its skull that are not seen in any other lizard. Description and history ''Ovoo'' is only known from a fossilized skull cataloged as IGM 3/767 and designated the holotype. The skull was discovered in 2001 near the rich Ukhaa Tolgod fossil site in a locality known as Little Ukhaa. The deposits at Little Uhhaa date back to the Campanian stage of the Late Cretaceous. The generic name is derived from the name of a type of cairn called ovoos that are found along roads near Little Ukhaa. The specific name, ''gurvel'', comes from the Mongolian word for lizard. ''Ovoo'' was very small compared to living monitor lizards, with the exception of the Short-tailed monitor. Nevertheless, the structures of its skull are very similar to those of living monitors. ''Ovoo'' shares many s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period. Climate During the Late Cretaceous, the climate was warmer than present, although throughout the period a cooling trend is evident. The tropics became restricted to equatorial regions and northern latitudes experienced markedly more seasonal climatic conditions. Geography Due to plate tectonics, the Americas were gradually moving westward, causing the Atlantic Ocean to expand. The Western Interior Seaway divided North America into eastern and western halves; Appalachia and Laramidia. India maintained a northward course towards Asia. In the Southern Hemisphere, Australia and Ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homology (biology)
In biology, homology is similarity due to shared ancestry between a pair of structures or genes in different taxa. A common example of homologous structures is the forelimbs of vertebrates, where the wings of bats and birds, the arms of primates, the front flippers of whales and the forelegs of four-legged vertebrates like dogs and crocodiles are all derived from the same ancestral tetrapod structure. Evolutionary biology explains homologous structures adapted to different purposes as the result of descent with modification from a common ancestor. The term was first applied to biology in a non-evolutionary context by the anatomist Richard Owen in 1843. Homology was later explained by Charles Darwin's theory of evolution in 1859, but had been observed before this, from Aristotle onwards, and it was explicitly analysed by Pierre Belon in 1555. In developmental biology, organs that developed in the embryo in the same manner and from similar origins, such as from matching p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lanthanotus
The earless monitor lizard (''Lanthanotus borneensis'') is a semiaquatic, brown lizard native to the Southeast Asian island of Borneo. It is the only living species in the family Lanthanotidae and it is related to the true monitor lizards. Taxonomy The earless monitor lizard was described in 1878 by Franz Steindachner. The genus name ''Lanthanotus'' means "hidden ear" and the species name ''borneensis'' refers to its home island of Borneo. The uniqueness of the species was recognized from the start and Steindachner placed it in its own family, Lanthanotidae. In 1899 George Albert Boulenger relegated it to the family Helodermatidae, together with the beaded lizards and gila monster. Further studies were conducted in the 1950s where it was found that although it is related to Helodermatidae, this relationship is relatively distant. The similarity is in part the result of convergent evolution and they should be recognized as separate families. Both are part of a broader Anguimorph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Necrosaurus
''Palaeovaranus'' is an extinct genus of varanoid lizards from the Late Eocene of France and Germany. It contains two species, ''Palaeovaranus cayluxensis'' and ''Palaeovaranus giganteus'' (formerly assigned to a separate genus ''Melanosauroides''). The genus was first named by Henri Filhol in 1877, but he had named the species ''Palaeovaranus cayluxi'' earlier as ''Palaeosaurus cayluxi'' in 1873, and as ''Necrosaurus cuxleyi'' in 1876 after it was discovered that ''Palaeosaurus'' was preoccupied. However, he failed to provide any kind of valid description, which renders Karl Alfred Ritter von Zittel's 1887 description of the taxon In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ... as the valid authority on its validity. Despite this, the name ''Necrosaurus'' was the widely used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saniwa
''Saniwa'' is an extinct genus of varanid lizard that lived about 48 million years ago during the Eocene epoch. It is known from well-preserved fossils found in the Bridger and Green River Formations of Wyoming. The type species ''S. ensidens'' was described in 1870 as the first fossil lizard known from North America. Several other species have since been added, but their validity is uncertain. It is a close relative of '' Varanus'', the genus that includes monitor lizards. Description ''Saniwa'' measured . Like other varanid lizards, ''Saniwa'' had a long, pointed snout and nostrils placed farther back in the skull than most lizards and a tail that was almost twice as long as the body. Although similar in appearance to extant monitor lizards, ''Saniwa'' had many primitive traits, including teeth on its palate, a jugal bone beneath the eye that extended farther forward, and a suture between the frontal and parietal bones that was straight rather than curved. A study in 2018 by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mosasaur
Mosasaurs (from Latin ''Mosa'' meaning the 'Meuse', and Greek ' meaning 'lizard') comprise a group of extinct, large marine reptiles from the Late Cretaceous. Their first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764. They belong to the order Squamata, which includes lizards and snakes. Mosasaurs probably evolved from an extinct group of aquatic lizards known as aigialosaurs in the Earliest Late Cretaceous with 42 described genera. During the last 20 million years of the Cretaceous period (Turonian–Maastrichtian ages), with the extinction of the ichthyosaurs and pliosaurs, mosasaurs became the dominant marine predators. They themselves became extinct as a result of the K-Pg event at the end of the Cretaceous period, about 66 million years ago. Description Mosasaurs breathed air, were powerful swimmers, and were well-adapted to living in the warm, shallow inland seas prevalent during the Late Cretaceous period. Mosasaurs were so ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladogram
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to descendants, nor does it show how much they have changed, so many differing evolutionary trees can be consistent with the same cladogram. A cladogram uses lines that branch off in different directions ending at a clade, a group of organisms with a last common ancestor. There are many shapes of cladograms but they all have lines that branch off from other lines. The lines can be traced back to where they branch off. These branching off points represent a hypothetical ancestor (not an actual entity) which can be inferred to exhibit the traits shared among the terminal taxa above it. This hypothetical ancestor might then provide clues about the order of evolution of various features, adaptation, and other evolutionary narratives about ance ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telmasaurus
''Telmasaurus'' is an extinct genus of varanoid lizard from the Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ... of Mongolia. Fossils have been found from the Djadokhta Formation, Djadokha and Barun Goyot Formations that date between the early and middle Campanian stage from approximately 80 to 75 million years ago. The type species ''Telmasaurus grangeri'' was named in 1943. Description ''Telmasaurus grangeri'' was named in 1943 and is now known from several fossils. Only two skulls are known, and the snout region is missing from both. Based on the size of these skulls, ''Telmasaurus'' was larger than other Cretaceous varanoid lizards, approaching the size of modern monitor lizards. Its skull is flatter than most other varanoids. The fusion of two bones in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lanthanotinae
The earless monitor lizard (''Lanthanotus borneensis'') is a semiaquatic, brown lizard native to the Southeast Asian island of Borneo. It is the only living species in the family Lanthanotidae and it is related to the true monitor lizards. Taxonomy The earless monitor lizard was described in 1878 by Franz Steindachner. The genus name ''Lanthanotus'' means "hidden ear" and the species name ''borneensis'' refers to its home island of Borneo. The uniqueness of the species was recognized from the start and Steindachner placed it in its own family, Lanthanotidae. In 1899 George Albert Boulenger relegated it to the family Helodermatidae, together with the beaded lizards and gila monster. Further studies were conducted in the 1950s where it was found that although it is related to Helodermatidae, this relationship is relatively distant. The similarity is in part the result of convergent evolution and they should be recognized as separate families. Both are part of a broader Anguimorph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basal (phylogenetics)
In phylogenetics, basal is the direction of the ''base'' (or root) of a phylogenetic tree#Rooted tree, rooted phylogenetic tree or cladogram. The term may be more strictly applied only to nodes adjacent to the root, or more loosely applied to nodes regarded as being close to the root. Note that extant taxa that lie on branches connecting directly to the root are not more closely related to the root than any other extant taxa. While there must always be two or more equally "basal" clades sprouting from the root of every cladogram, those clades may differ widely in taxonomic rank, Phylogenetic diversity, species diversity, or both. If ''C'' is a basal clade within ''D'' that has the lowest rank of all basal clades within ''D'', ''C'' may be described as ''the'' basal taxon of that rank within ''D''. The concept of a 'key innovation' implies some degree of correlation between evolutionary innovation and cladogenesis, diversification. However, such a correlation does not make a given ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Varanidae
The Varanidae are a family of lizards in the superfamily Varanoidea within the Anguimorpha group. The family, a group of carnivorous and frugivorous lizards, includes the living genus '' Varanus'' and a number of extinct genera more closely related to ''Varanus'' than to the earless monitor lizard (''Lanthanotus''). ''Varanus'' includes the Komodo dragon (the largest living lizard), crocodile monitor, savannah monitor, the goannas of Australia and Southeast Asia, and various other species with a similarly distinctive appearance. Their closest living relatives are the earless monitor lizard and chinese crocodile lizard. The oldest members of the family are known from the Late Cretaceous of Mongolia. Taxonomy The Varanidae were defined (using morphological characteristics) by Estes, de Queiroz and Gauthier (1988) as the clade containing the most recent common ancestor of ''Lanthanotus'' and ''Varanus'' and all of its descendants. A similar definition was formulated by Conrad ''et al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
