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Peraiocynodon
''Peraiocynodon'' is an extinct mammaliaform from the order Docodonta, found in the Middle Jurassic rocks of the United Kingdom. It is only known from isolated molar teeth found in the mammal bed at Kirtlington cement quarry in Oxfordshire, England (Forest Marble Formation). ''Peraiocynodon'' was originally erected in 1929 with a single species named,Simpson GG. 1928. A Catalogue of the Mesozoic Mammalia in the Geological Department of the British Museum. British Museum. but it was later considered to be a synonym of ''Docodon''.Butler PM. 1939The teeth of the Jurassic mammals In Proceedings of the Zoological Society of London, 109:329-356). Oxford, UK: Blackwell Publishing Ltd. However, in 2003, the genus was resurrected and a new species, ''P. major'', was described based on new teeth found at Kirtington Cement Quarry in Oxfordshire.Sigogneau-Russell D. 2003Docodonts from the British Mesozoic Acta Palaeontologica Polonica, 48(3) It remains uncertain whether one or both of these ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Docodonta
Docodonta is an Order (biology), order of extinct Mammaliaformes, mammaliaforms that lived during the Mesozoic, from the Middle Jurassic to Early Cretaceous. They are distinguished from other early Mammaliaformes, mammaliaforms by their relatively complex Molar (tooth), molar teeth, from which the order gets its name. Until recently, Docodonta were represented primarily by teeth and jaws found across former Laurasia, (modern-day North America, Europe, and Asia). However, recent discoveries in China include some exceptionally well preserved, almost complete body fossils. Description Skeletal traits Docodonts have a long and low mandible (lower jaw), formed primarily by the tooth-bearing dentary bone. The dentary connects to the cranium via a joint with the Squamosal bone, squamosal, a connection which is strengthened relative to earlier mammaliaforms. The other bones in the jaw, known as postdentary elements, are still connected to the dentary and lie within a groove (the postd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Docodonts
Docodonta is an order of extinct mammaliaforms that lived during the Mesozoic, from the Middle Jurassic to Early Cretaceous. They are distinguished from other early mammaliaforms by their relatively complex molar teeth, from which the order gets its name. Until recently, Docodonta were represented primarily by teeth and jaws found across former Laurasia, (modern-day North America, Europe, and Asia). However, recent discoveries in China include some exceptionally well preserved, almost complete body fossils. Description Skeletal traits Docodonts have a long and low mandible (lower jaw), formed primarily by the tooth-bearing dentary bone. The dentary connects to the cranium via a joint with the squamosal, a connection which is strengthened relative to earlier mammaliaforms. The other bones in the jaw, known as postdentary elements, are still connected to the dentary and lie within a groove (the postdentary trough) in the rear part of the dentary’s inner edge. Nevertheless, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forest Marble Formation
The Forest Marble is a geological formation in England. Part of the Great Oolite Group, it dates to the late Bathonian stage of the Middle Jurassic.Weishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 538–541. . Lithology The primary lithology of the formation typically consists of greenish grey variably calcareous silicate mudstone, with lenticular cross bedded limestone units deposited in a marine setting. Dinosaurian fauna Ornithischians Saurischians Microvertebrate fauna Despite the formation being nearly entirely marine, at several localities abundant remains of terrestrial microvertebrates are found, the primary locality being the Kirtlington Mammal Bed (designated 3p) in Kirtlington Quarry near Kirtlington, Oxfordshire. Another important locality is Watton Cliff near Eype in Dorset. Amp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from about 174.1 to 163.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relatively rare, but geological formations containing land animal fossils include the Forest Marble Formation in England, the Kilmaluag Formation in Scotland,British Geological Survey. 2011Stratigraphic framework for the Middle Jurassic strata of Great Britain and the adjoining continental shelf: research report RR/11/06 British Geological Survey, Keyworth, Nottingham. the Daohugou Beds in China, the Itat Formation in Russia, and the Isalo III Formation of western Madagascar. Paleogeography During the Middle Jurassic Epoch, Pangaea began to separate into Laurasia and Gondwana, and the Atlantic Ocean formed. Eastern Laurasia was tectonically active as the Cimmerian plate continued to collide with Laurasia's southern coast, completely closing the Paleo-Tethys Ocean. A subduction zone ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Gaylord Simpson
George Gaylord Simpson (June 16, 1902 – October 6, 1984) was an American paleontologist. Simpson was perhaps the most influential paleontologist of the twentieth century, and a major participant in the Modern synthesis (20th century), modern synthesis, contributing ''Tempo and Mode in Evolution'' (1944), ''The Meaning of Evolution'' (1949) and ''The Major Features of Evolution'' (1953). He was an expert on extinct mammals and their intercontinental migrations. Simpson was extraordinarily knowledgeable about Mesozoic fossil mammals and fossil mammals of North and South America. He anticipated such concepts as punctuated equilibrium (in ''Tempo and Mode'') and dispelled the myth that the evolution of the horse was a linear process culminating in the modern ''Equus caballus''. He coined the word ''wikt:hypodigm, hypodigm'' in 1940, and published extensively on the Taxonomy (biology), taxonomy of fossil and extant mammals. Simpson was influentially, and incorrectly, opposed to Alf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammaliaform
Mammaliaformes ("mammalian forms") is a clade that contains the crown group mammals and their closest extinct relatives; the group radiated from earlier probainognathian cynodonts. It is defined as the clade originating from the most recent common ancestor of Morganucodonta and the crown group mammals; the latter is the clade originating with the most recent common ancestor of extant Monotremata, Marsupialia, and Placentalia. Besides Morganucodonta and the crown group mammals, Mammaliaformes includes Docodonta and '' Hadrocodium'' as well as the Triassic ''Tikitherium'', the earliest known member of the group. Mammaliaformes is a term of phylogenetic nomenclature. In contrast, the assignment of organisms to Mammalia has traditionally been founded on traits and, on this basis, Mammalia is slightly more inclusive than Mammaliaformes. In particular, trait-based taxonomy generally includes ''Adelobasileus'' and ''Sinoconodon'' in Mammalia, though they fall outside the Mammaliaform ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kirtlington
Kirtlington is a village and civil parish in Oxfordshire about west of Bicester. The parish includes the hamlet of Northbrook. The 2011 Census recorded the parish's population as 988. The parish measures nearly north–south and about east–west. It is bounded by the River Cherwell to the west, and elsewhere mostly by field boundaries. In 1959 its area was . Archaeology The Portway is a pre-Roman road running parallel with the Cherwell on high ground about east of the river. It bisects Kirtlington parish and passes through the village. A short stretch of it is now part of the A4095 road through the village. Longer stretches form minor roads to Bletchingdon and Upper Heyford. Akeman Street Roman road bisects the parish east–west passing just north of Kirtlington village. A minor road linking Kirtlington with Chesterton uses its course. Aves ditch is pre-Saxon. One end of the ditch is in Kirtlington parish about north of the village. Just east of the parish school is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Docodon
''Docodon'' (meaning 'beam tooth') was a mammaliaform from the Late Jurassic of western North America. It was the first docodontan cynodont to be named. Description ''Docodon'' was the first docodontan cynodont found and named, and later gave its name to the family Docodontidae as well as the order Docodonta.Kretzoi, M. (1946). "On Docodonta, a new order of Jurassic Mammals". ''Anneles Historico-Naturales Musei Nationalis Hungarici''. 39 :108-111. Docodonts had more complex shaped teeth than other early non-mammalian mammaliaforms, with piercing and crushing surfaces that would have allowed members of this family to eat a wider range of food types. These complex teeth are more similar to those of later mammal groups, but evolved independently of them. Unlike many of its coexisting mammal relatives from the Mesozoic, ''Docodon'' is known from a large number of teeth and jaws of differing growth stages. This has made it possible to study the growth of this docodontan, and has rev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic Synapsids Of Europe
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic Magmatic Province. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and is the only boundary between geological periods to remain formally undefined. By the beginning of the Jurassic, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil Taxa Described In 1929
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the absolute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
