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Younginiformes
Younginiformes is a replacement name for the taxon Eosuchia, proposed by Alfred Romer in 1947. The Eosuchia having become a wastebasket taxon for many probably distantly-related primitive diapsid reptiles ranging from the late Carboniferous to the Eocene, Romer proposed that this be replaced by Younginiformes, to include the Younginidae and a very few similar families, ranging from the Permian to the Triassic. Younginiformes (including ''Acerosodontosaurus'', ''Hovasaurus'', ''Kenyasaurus'', ''Tangasaurus'', ''Thadeosaurus'', ''Youngina'', et alia sensu Currie and other researchers in the 1980s) is probably not a clade. It appears to represent a grade of South African Permo-Triassic diapsids that are not more closely related to each other as a whole than they are to other reptiles. A cladistic analysis by Laurin and Pineiro (2017) recovers Parareptilia Parareptilia ("at the side of reptiles") is a subclass or clade of basal sauropsids (reptiles), typically considered the sis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kenyasaurus
''Kenyasaurus'' is an extinct genus of basal tangasaurid known from the Early Triassic period of Coast Province, southeastern Kenya. It contains a single species, ''Kenyasaurus mariakaniensis''. Discovery ''Kenyasaurus'' is known only from the holotype specimen, KNM-MA1, a well preserved and partially complete postcranial skeleton, lacking much of the neck, pectoral girdle and forelimb, which is hosted at the Kenya National Museum. It was found at the Mariakani locality which is located 25 miles from Mombasa, southeastern Kenya. It was collected from the upper part of the Maji ya Chumvi Beds ( Maji-Ya-Chumvi Formation). These beds form the lower part of the Middle Duruma Sandstone Series (Duruma Group) and on the basis of lithological similarities with beds in Tanzania and Madagascar were dated to the Induan and Olenekian stages of the Early Triassic period, about 251.0-245 million years ago. This specimen represents the only reptilian fossils currently known from these be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acerosodontosaurus
''Acerosodontosaurus'' is an extinct genus of neodiapsid reptiles that lived during the Upper Permian of Madagascar. The only species of ''Acerosodontosaurus'', ''A. piveteaui'', is known from a natural mold of a single partial skeleton including a crushed skull and part of the body and limbs. The fossil was discovered in marine deposits of the Lower Sakamena Formation. In conjunction with several skeletal characteristics, this may indicate that ''Acerosodontosaurus'' individuals were at least partially aquatic. ''Acerosodontosaurus'' has generally been considered a " younginiform", part of a paraphyletic grade of Permian diapsids which linked the most basal ("primitive") diapsids (araeoscelidians such as ''Petrolacosaurus'') to more derived ("advanced") diapsids, including the earliest ancestors of modern reptiles such as crocodilians and lizards. However, its position within the grade is controversial. Initially considered a specimen of the contemporaneous ''Tangasaurus'', '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tangasaurus
''Tangasaurus'' is an extinct genus of aquatic basal tangasaurid neodiapsid known from the Late Permian period (late Changhsingian stage) of Tanga, northeastern Tanzania. It contains a single species, ''Tangasaurus mennelli''. Discovery ''Tangasaurus'' is known only from three syntypes which represent two individuals. The small individual, which is well preserved in two specimens ( part and counterpart) and is known from a partial skull and a nearly complete postcranial skeleton, was designated as the lectotype of the genus. The part slab (showing the partial skull and postcranial) is hosted at the Bulawayo Museum, Zimbabwe, while the counterpart slab SAM 6231 (showing the other side of the postcranial) is hosted at the South African Museum, Cape Town. The third syntype, SAM 6232, represents a nearly complete postcranial skeleton from a larger individual, but it is poorly preserved. All specimens were collected by F. P. Mennell in 1922 at the Mizimbazi River near ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tangasauridae
Tangasauridae is a family of diapsids. Specimens have been found that are of Late Permian to Early Triassic in age from the Sakamena Group of western Madagascar. They lived alongside other taxa present from the Sakamena Group, including temnospondyls, rhynchosaurs, and gomphodont eucynodonts. Fossils have been found of numerous specimens of common members of this family such as ''Hovasaurus'' and ''Thadeosaurus'' in different stages of ontogenic development.Currie, Philip J and Carroll, Robert L. (1984) Ontogenic changes in the eosuchian reptile ''Thadeosaurus''. ''Journal of Vertebrate Paleontology'' 4(1):68-84 Recent material from the Middle Sakamena Formation of the Morondava Basin of Madagascar that dates back to the early Triassic period suggests that the Tangasauridae were relatively unaffected by the Permian-Triassic extinction event. Description and phylogeny Tangasaurids are known to have been a highly derived group of diapsids. One subfamily, Kenyasaurinae, is com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Younginidae
Younginidae is an extinct family of neodiapsid reptiles from the Late Permian and Early Triassic. In a phylogenetic context, younginids are near the base of the clade Neodiapsida. Younginidae includes the species ''Youngina capensis'' from the Late Permian of South Africa and '' Thadeosaurus colcanapi'' from the Late Permian and Early Triassic of Madagascar. ''Heleosuchus griesbachi'' from the Late Permian of South Africa may also be a member of the family. Younginidae was traditionally assigned to Eosuchia, an order containing an assemblage of basal diapsids now thought to represent an evolutionary grade rather than a true clade. In 1945 paleontologist Alfred Romer reclassified Younginidae within a new group, Younginiformes, grouping it with the families Tangasauridae and Prolacertidae. Romer considered Younginidae to include many genera that are no longer classified as younginids: ''Paliguana'', '' Palaegama'', and ''Saurosternon'' are now considered basal lepidosauromorphs, '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eosuchia
Eosuchians are an extinct order of diapsid reptiles. Depending on which taxa are included the order may have ranged from the late Carboniferous to the Eocene but the consensus is that eosuchians are confined to the Permian and Triassic. Eosuchia was initially defined to include all "thecodontian" reptiles which did not have an antorbital fenestra but did retain tabulars, postparietals and a large pineal foramen (Broom, 1914). Broom coined the term as a new suborder for ''Youngina''. A definition for inclusion in the order is difficult: it is almost easier to list the primitively-diapsid reptiles that have not been included at one time or another. The order has almost been treated as a dustbin for diapsids that are not obviously lepidosaurian or archosaurian. One consequence has been Romer's suggestion of the alternative order Younginiformes to be applied strictly to those forms with the primitive diapsid form, in particular, a complete lowermost arch as the quadratojugal and j ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parareptilia
Parareptilia ("at the side of reptiles") is a subclass or clade of basal sauropsids (reptiles), typically considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds). Parareptiles first arose near the end of the Carboniferous period and achieved their highest diversity during the Permian period. Several ecological innovations were first accomplished by parareptiles among reptiles. These include the first reptiles to return to marine ecosystems (mesosaurs), the first bipedal reptiles ( bolosaurids such as ''Eudibamus''), the first reptiles with advanced hearing systems ( nycteroleterids and others), and the first large herbivorous reptiles (the pareiasaurs). The only parareptiles to survive into the Triassic period were the procolophonoids, a group of small generalists, omnivores, and herbivores. The largest family of procolophonoids, the procolophonids, rediversified in the Triassic, but subsequently declined and became extinct by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Youngina
''Youngina'' is an extinct genus of diapsid reptile from the Late Permian Beaufort Group (''Tropidostoma''-''Dicynodon'' zones) of the Karoo Red Beds of South Africa. This, and a few related forms, make up the family Younginidae, within the Order Eosuchia (proposed by Broom in 1914). Eosuchia, having become a wastebasket taxon for many probably distantly-related primitive diapsid reptiles ranging from the Late Carboniferous to the Eocene, Romer proposed that it be replaced by Younginiformes (that included Younginidae and the Tangasauridae, ranging from the Permian to the Triassic). ''Youngina'' is known from several specimens. Many of these were attributed to as separate genera and species (such as ''Youngoides'' and ''Youngopsis''), but it was later realized that they were not distinct from ''Y. capensis''. The holotype specimen of ''Youngina'' was described briefly in 1914. The "''Youngoides romeri''" specimen was first attributed to ''Youngina'', but later given its eponymous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triassic Diapsids
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events. The Triassic Period is subdivided into three epochs: Early Triassic, Middle Triassic and Late Triassic. The Triassic began in the wake of the Permian–Triassic extinction event, which left the Earth's biosphere impoverished; it was well into the middle of the Triassic before life recovered its former diversity. Three categories of organisms can be distinguished in the Triassic record: survivors from the extinction event, new groups that flourished briefly, and other new groups that went on to dominate the Mesozoic Era. Reptiles, especially archosaurs, were the chief terrestrial vertebrates during this time. A specialized subgroup of archosaurs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permian Reptiles
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleozoic Era; the following Triassic Period belongs to the Mesozoic Era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the region of Perm in Russia. The Permian witnessed the diversification of the two groups of amniotes, the synapsids and the sauropsids (reptiles). The world at the time was dominated by the supercontinent Pangaea, which had formed due to the collision of Euramerica and Gondwana during the Carboniferous. Pangaea was surrounded by the superocean Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior. Amniotes, which could better cope with these drier conditions, rose to dominance in place of their amphibian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraphyletic Groups
In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In contrast, a monophyletic group (a clade) includes a common ancestor and ''all'' of its descendants. The terms are commonly used in phylogenetics (a subfield of biology) and in the tree model of historical linguistics. Paraphyletic groups are identified by a combination of synapomorphies and symplesiomorphies. If many subgroups are missing from the named group, it is said to be polyparaphyletic. The term was coined by Willi Hennig to apply to well-known taxa like Reptilia (reptiles) which, as commonly named and traditionally defined, is paraphyletic with respect to mammals and birds. Reptilia contains the last common ancestor of reptiles and all descendants of that ancestor, including all extant reptiles as well as the extinct synapsids, exce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, the equivalent Latin term ''cladus'' (plural ''cladi'') is often used in taxonomical literature. The common ancestor may be an individual, a population, or a species (extinct or extant). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups. Over the last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic. Some of the relationships between organisms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
