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Australochelys
''Australochelys'' is an extinct genus of rhaptochelydian turtle. It is known from one species, ''A. africanus'', that came from the Elliot Formation of South Africa. The holotype of ''Australochelys'' consists of only a skull and a fragment of the carapace, which shows both primitive and derived features. Like ''Proganochelys'', ''Australochelys'' has large orbits and a ventral basioccipital tubercle, but like derived turtles such as casichelydians, a group containing Cryptodira and Pleurodira, it possesses a sutured basipterygoidal attachment, and a middle ear region partially enclosed laterally. These characteristics show that ''Australochelys'' is more closely related to casichelydians than to ''Proganochelys'', and together with the former, it makes up Rhaptochelydia. The skull of ''Australochelys'' shows that an advanced hearing mechanism of turtles evolved before the appearance of modern turtles. Etymology ''Australochelys africanus'' was named in 1994 by Eugene S. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhaptochelydia
Testudinata is the group of all tetrapods with a true turtle shell. It includes both modern turtles (Testudines) and many of their extinct, shelled relatives (stem-turtles). Though it was first coined as the group containing turtles by Jacob Theodor Klein in 1760, it was first defined in the modern sense by Joyce and colleagues in 2004. Testudinata does not include the primitive stem-turtle ''Odontochelys'', which only had the bottom half of a shell. A recent phylogenetic tree of Testudinata included Angolachelonia and Testudines Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked ... as sister-taxa and subgroups of Testudinata. Classification The cladogram below follows an analysis by Jérémy Anquetin in 2012. References {{Taxonbar, from=Q16114972 Reptile taxonomy Norian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proganochelys
''Proganochelys'' is an extinct, primitive stem-turtle that has been hypothesized to be the sister taxon to all other turtles creating a monophyletic group, the ''Casichelydia''. ''Proganochelys'' was named by Georg Baur in 1887 as the oldest turtle in existence at the time. The name ''Proganochelys'' comes from the Greek word ''ganos'' meaning 'brightness', combined with prefix ''pro'', 'before', and Greek base ''chelys'' meaning 'turtle'. ''Proganochelys'' is believed to have been around 1 meter in size and herbivorous in nature. ''Proganochelys'' was known as the most primitive stem-turtle for over a century, until the novel discovery of ''Odontochelys'' in 2008. ''Odontochelys'' and ''Proganochelys'' share unique primitive features that are not found in ''Casichelydia'', such as teeth on the pterygoid and vomer and a plate-like coracoid. ''Proganochelys'' is the oldest stem-turtle species with a complete shell discovered to date, known from fossils found in Germany, Switzerla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Jurassic
The Early Jurassic Epoch (in chronostratigraphy corresponding to the Lower Jurassic Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-Jurassic extinction event, 201.3 Ma (million years ago), and ends at the start of the Middle Jurassic 174.1 Ma. Certain rocks of marine origin of this age in Europe are called "Lias" and that name was used for the period, as well, in 19th-century geology. In southern Germany rocks of this age are called Black Jurassic. Origin of the name Lias There are two possible origins for the name Lias: the first reason is it was taken by a geologist from an English quarryman's dialect pronunciation of the word "layers"; secondly, sloops from north Cornish ports such as Bude would sail across the Bristol Channel to the Vale of Glamorgan to load up with rock from coastal limestone quarries (lias limestone from South Wales was used throughout North Devon/North Cornwall as it conta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age. In the past, ''Malm'' was also used to indicate the unit of geological time, but this usage is now discouraged to make a clear distinction between lithostratigraphic and geochronologic/chronostratigraphic units. Subdivisions The Late Jurassic is divided into three ages, which correspond with the three (faunal) stages of Upper Jurassic rock: Paleogeography During the Late Jurassic Epoch, Pangaea broke up into two supercontinents, Laurasia to the north, and Gondwana to the south. The result of this break-up was the spawning of the Atlantic Ocean. However, at this time, the Atlantic Ocean was relatively narrow. Life forms of the epoch This epoch is well known for many famous types of din ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gokwe Formation
The Gokwe Formation is an Early Cretaceous geologic formation in Zimbabwe. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607. Sediments of the formation may have been laid down in a small shallow lake, carried by intermittent floods from a land surface surrounding the lake on which aeolian transport of sand took place. More likely the animals died on a dry lake bed, and their bones were exposed to a period of desiccation, later floods would scatter the fragments and incorporate them in sediment. at .org See also |
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area and 20% of its land area.Sayre, April Pulley (1999), ''Africa'', Twenty-First Century Books. . With billion people as of , it accounts for about of the world's human population. Africa's population is the youngest amongst all the continents; the median age in 2012 was 19.7, when the worldwide median age was 30.4. Despite a wide range of natural resources, Africa is the least wealthy continent per capita and second-least wealthy by total wealth, behind Oceania. Scholars have attributed this to different factors including geography, climate, tribalism, Scramble for Africa, colonialism, the Cold War, neocolonialism, lack of democracy, and corruption. Despite this low concentration of wealth, recent economic expansion and the large and young ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Testudines
Turtles are an order of reptiles known as Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked turtles), which differ in the way the head retracts. There are 360 living and recently extinct species of turtles, including land-dwelling tortoises and freshwater terrapins. They are found on most continents, some islands and, in the case of sea turtles, much of the ocean. Like other amniotes (reptiles, birds, and mammals) they breathe air and do not lay eggs underwater, although many species live in or around water. Turtle shells are made mostly of bone; the upper part is the domed carapace, while the underside is the flatter plastron or belly-plate. Its outer surface is covered in scales made of keratin, the material of hair, horns, and claws. The carapace bones develop from ribs that grow sideways and develop into broad flat plat ... [...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 an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Premaxilla
The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has been usually termed as the incisive bone. Other terms used for this structure include premaxillary bone or ''os premaxillare'', intermaxillary bone or ''os intermaxillare'', and Goethe's bone. Human anatomy In human anatomy, the premaxilla is referred to as the incisive bone (') and is the part of the maxilla which bears the incisor teeth, and encompasses the anterior nasal spine and alar region. In the nasal cavity, the premaxillary element projects higher than the maxillary element behind. The palatal portion of the premaxilla is a bony plate with a generally transverse orientation. The incisive foramen is bound anteriorly and laterally by the premaxilla and posteriorly by the palatine process of the maxilla. It is formed from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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