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Araeoscelidians
Araeoscelidia or Araeoscelida is a clade of extinct diapsid reptiles superficially resembling lizards, extending from the Late Carboniferous to the Early Permian. The group contains the genera '' Araeoscelis'', ''Petrolacosaurus'', the possibly aquatic '' Spinoaequalis'', and less well-known genera such as '' Kadaliosaurus'' and ''Zarcasaurus''. This clade is considered to be the sister group to all (currently known) later diapsids. Description Araeoscelidians were small animals (less than one meter in length) looking somewhat like lizards, though they are only distantly related to true lizards. They differ from other, earlier sauropsids by their slender limbs, their elongated tail, and of course by the presence of two temporal openings, the feature defining the diapsid condition. In '' Araeoscelis'', only the upper temporal opening remains, thus resulting in a derived euryapsid condition. Genera Araeoscelidia includes well-known genera such as '' Araeoscelis'' Willisto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Araeosceloidea
Araeoscelidia or Araeoscelida is a clade of extinct diapsid reptiles superficially resembling lizards, extending from the Late Carboniferous to the Early Permian. The group contains the genera ''Araeoscelis'', ''Petrolacosaurus'', the possibly aquatic '' Spinoaequalis'', and less well-known genera such as '' Kadaliosaurus'' and ''Zarcasaurus''. This clade is considered to be the sister group to all (currently known) later diapsids. Description Araeoscelidians were small animals (less than one meter in length) looking somewhat like lizards, though they are only distantly related to true lizards. They differ from other, earlier sauropsids by their slender limbs, their elongated tail, and of course by the presence of two temporal openings, the feature defining the diapsid condition. In ''Araeoscelis'', only the upper temporal opening remains, thus resulting in a derived euryapsid condition. Genera Araeoscelidia includes well-known genera such as ''Araeoscelis'' Williston 1910, '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Araeoscelinae
Araeoscelidia or Araeoscelida is a clade of extinct diapsid reptiles superficially resembling lizards, extending from the Late Carboniferous to the Early Permian. The group contains the genera ''Araeoscelis'', ''Petrolacosaurus'', the possibly aquatic '' Spinoaequalis'', and less well-known genera such as '' Kadaliosaurus'' and ''Zarcasaurus''. This clade is considered to be the sister group to all (currently known) later diapsids. Description Araeoscelidians were small animals (less than one meter in length) looking somewhat like lizards, though they are only distantly related to true lizards. They differ from other, earlier sauropsids by their slender limbs, their elongated tail, and of course by the presence of two temporal openings, the feature defining the diapsid condition. In ''Araeoscelis'', only the upper temporal opening remains, thus resulting in a derived euryapsid condition. Genera Araeoscelidia includes well-known genera such as ''Araeoscelis'' Williston 1910, '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carboniferous
The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carboniferous'' means "coal-bearing", from the Latin '' carbō'' ("coal") and '' ferō'' ("bear, carry"), and refers to the many coal beds formed globally during that time. The first of the modern 'system' names, it was coined by geologists William Conybeare and William Phillips in 1822, based on a study of the British rock succession. The Carboniferous is often treated in North America as two geological periods, the earlier Mississippian and the later Pennsylvanian. Terrestrial animal life was well established by the Carboniferous Period. Tetrapods (four limbed vertebrates), which had originated from lobe-finned fish during the preceding Devonian, became pentadactylous in and diversified during the Carboniferous, including early amphibian line ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus comes above species and below family (taxonomy), family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus ''Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomy (biology), taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crown Group
In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. It is thus a way of defining a clade, a group consisting of a species and all its extant or extinct descendants. For example, Neornithes (birds) can be defined as a crown group, which includes the most recent common ancestor of all modern birds, and all of its extant or extinct descendants. The concept was developed by Willi Hennig, the formulator of phylogenetic systematics, as a way of classifying living organisms relative to their extinct relatives in his "Die Stammesgeschichte der Insekten", and the "crown" and "stem" group terminology was coined by R. P. S. Jefferies in 1979. Though formulated in the 1970s, the term was not commonly used until its reintroduction in 2000 by Graham Budd and Sören Jensen. Contents of the crown gr ... [...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] |
Neodiapsida
Neodiapsida is a clade, or major branch, of the reptilian family tree, typically defined as including all diapsids apart from some early primitive types known as the araeoscelidians. Modern reptiles and birds belong to the neodiapsid subclade Sauria. The oldest known neodiapsid is generally considered to be ''Orovenator'' from the Early Permian (Cisuralian) of North America. Basal-non saurian neodiaspids were ancestrally lizard-like, but basal Permian neodiapsids also include specialised swimming forms (''Hovasaurus'') the gliding lizard-like Weigeltisauridae, as well as the Triassic chameleon-like drepanosaurs. The position of the highly derived Mesozoic marine reptile groups Thalattosauria, Ichthyosauromorpha and Sauropterygia within Neodiapsida is uncertain, and they may lie within Sauria. Classification The clade Neodiapsida was given a phylogenetic definition by Laurin in 1991. He defined it as the branch-based clade containing all animals more closely related to "Youngin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diapsida
Diapsids ("two arches") are a clade of sauropsids, distinguished from more primitive eureptiles by the presence of two holes, known as temporal fenestrae, in each side of their skulls. The group first appeared about three hundred million years ago during the late Carboniferous period. All diapsids other than the most primitive ones in the clade Araeoscelidia are sometimes placed into the clade Neodiapsida. The diapsids are extremely diverse, and include birds and all modern reptile groups, including turtles, which were historically thought to lie outside the group. Although some diapsids have lost either one hole (lizards), or both holes (snakes and turtles), or have a heavily restructured skull (modern birds), they are still classified as diapsids based on their ancestry. At least 17,084 species of diapsid animals are extant: 9,159 birds, and 7,925 snakes, lizards, tuatara, turtles, and crocodiles. Characteristics The name Diapsida means "two arches", and diapsids are tradition ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesosaur
Mesosaurs ("middle lizards") were a group of small aquatic reptiles that lived during the early Permian period, roughly 299 to 270 million years ago. Mesosaurs were the first known aquatic reptiles, having apparently returned to an aquatic lifestyle from more terrestrial ancestors. It is uncertain which and how many terrestrial traits these ancestors displayed; recent research cannot establish with confidence if the first amniotes were fully terrestrial, or only amphibious. Most authors consider mesosaurs to have been aquatic, although adult animals may have been amphibious, rather than completely aquatic, as indicated by their moderate skeletal adaptations to a semiaquatic lifestyle.Pablo Nuñez Demarco et al. Was Mesosaurus a Fully Aquatic Reptile? Front. Ecol. Evol, published online July 27, 2018; doi: 10.3389/fevo.2018.00109 Similarly, their affinities are uncertain; they may have been among the most basal sauropsids or among the most basal parareptiles (in the case of whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protorosaurus
''Protorosaurus'' ("first lizard") is a genus of lizard-like early reptiles. Members of the genus lived during the late Permian period in what is now Germany and Great Britain. Once believed to have been an ancestor to lizards, ''Protorosaurus'' is now known to be one of the oldest and most primitive members of Archosauromorpha, the group that would eventually lead to archosaurs such as crocodilians and dinosaurs. Description ''Protorosaurus'' grew up to in length, and was a slender, lizard-like animal, vaguely resembling a monitor lizard, with long legs and a long neck. Discovery ''Protorosaurus'' was one of the first fossil reptiles to be described, being initially described in Latin in 1710 by from a specimen found in Thuringia in Germany, who considered the animal to be a crocodile, and most similar to the Nile crocodile (''C. niloticus''). Over a century later, in publications in 1830 and 1832 Hermann von Meyer recognised ''Protorosaurus'' as distinct extinct reptile a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euryapsid
__NOTOC__ Euryapsida is a polyphyletic (unnatural, as the various members are not closely related) group of sauropsids that are distinguished by a single temporal fenestra, an opening behind the orbit, under which the post-orbital and squamosal bones articulate. They are different from Synapsida, which also have a single opening behind the orbit, by the placement of the fenestra. In synapsids, this opening is below the articulation of the post-orbital and squamosal bones. It is now commonly believed that euryapsids are in fact diapsids (which have two fenestrae behind the orbit) that lost the lower temporal fenestra. There are probably no surviving descendants of the euryapsids. The term Enaliosauria was once used for ichthyosaurs and plesiosaurs combined as well. See also * Anapsida * Diapsida Diapsids ("two arches") are a clade of sauropsids, distinguished from more primitive eureptiles by the presence of two holes, known as temporal fenestrae, in each side of their skulls. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
