|
Sinonyx
''Sinonyx'' ("Chinese claw") is a genus of extinct, superficially wolf-like mesonychid mammals from the late Paleocene of China (about 56 million years ago). It is within the family Mesonychidae, and cladistic analysis of a skull of ''Sinonyx'' ''jiashanensis'' identifies its closest relative as ''Ankalagon''. ''S.'' ''jiashanensis'' was discovered in Anhui province, China (, paleocoordinates ), in the Tuijinshan formation. Description ''Sinonyx'' was about 1.5 m (5 ft) long, about the size of a modern grey wolf with a large elongated head, short legs, digitigrade feet adapted for running, and tiny hooves on all of its toes. The tooth count was 3.1.4.3=44, the primitive mammalian number. The canines were long and slender. Compressed teeth with shearing notches in the lower jaw operated against multiple-cusped molars in the upper. The large skull had an extended occipital bone and large sagittal crest that contained the small brain typical of early mammals. The sagitta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinonyx Jiashanensis Cropped
''Sinonyx'' ("Chinese claw") is a genus of extinct, superficially Grey Wolf, wolf-like mesonychid mammals from the late Paleocene of China (about 56 million years ago). It is within the family Mesonychidae, and cladistic analysis of a skull of ''Sinonyx'' ''jiashanensis'' identifies its closest relative as Ankalagon saurognathus, ''Ankalagon''. ''S.'' ''jiashanensis'' was discovered in Anhui province, China (, paleocoordinates ), in the Tuijinshan formation. Description ''Sinonyx'' was about 1.5 m (5 ft) long, about the size of a modern grey wolf with a large elongated head, short legs, digitigrade feet adapted for running, and tiny hooves on all of its toes. The tooth count was 3.1.4.3=44, the primitive mammalian number. The canines were long and slender. Compressed teeth with shearing notches in the lower jaw operated against multiple-cusped molars in the upper. The large skull had an extended :wikt:occipital, occipital bone and large sagittal crest that contained the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sinonyx Jiashanensis Skull
''Sinonyx'' ("Chinese claw") is a genus of extinct, superficially wolf-like mesonychid mammals from the late Paleocene of China (about 56 million years ago). It is within the family Mesonychidae, and cladistic analysis of a skull of ''Sinonyx'' ''jiashanensis'' identifies its closest relative as ''Ankalagon''. ''S.'' ''jiashanensis'' was discovered in Anhui province, China (, paleocoordinates ), in the Tuijinshan formation. Description ''Sinonyx'' was about 1.5 m (5 ft) long, about the size of a modern grey wolf with a large elongated head, short legs, digitigrade feet adapted for running, and tiny hooves on all of its toes. The tooth count was 3.1.4.3=44, the primitive mammalian number. The canines were long and slender. Compressed teeth with shearing notches in the lower jaw operated against multiple-cusped molars in the upper. The large skull had an extended occipital bone and large sagittal crest that contained the small brain typical of early mammals. The sagittal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleocene
The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name is a combination of the Ancient Greek ''palaiós'' meaning "old" and the Eocene Epoch (which succeeds the Paleocene), translating to "the old part of the Eocene". The epoch is bracketed by two major events in Earth's history. The K–Pg extinction event, brought on by Chicxulub impact, an asteroid impact and possibly volcanism, marked the beginning of the Paleocene and killed off 75% of living species, most famously the non-avian dinosaurs. The end of the epoch was marked by the Paleocene–Eocene Thermal Maximum (PETM), which was a major climatic event wherein about 2,500–4,500 gigatons of carbon were released into the atmosphere and ocean systems, causing a spike in global temperatures and ocean acidification. In the Pal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesonychidae
Mesonychidae (meaning "middle claws") is an extinct family of small to large-sized omnivorous-carnivorous mammals. They were endemic to North America and Eurasia during the Early Paleocene to the Early Oligocene, and were the earliest group of large carnivorous mammals in Asia. They are not closely related to any living mammals. Mesonychid taxonomy has long been disputed and they have captured popular imagination as "wolves on hooves," animals that combine features of both ungulates and carnivores. Skulls and teeth have similar features to early whales, and the family was long thought to be the ancestors of cetaceans. Recent fossil discoveries have overturned this idea; the consensus is that whales are highly derived artiodactyls. Some researchers now consider the family a sister group either to whales or to artiodactyls, close relatives rather than direct ancestors. Other studies define Mesonychia as basal to all ungulates, occupying a position between Perissodactyla and Ferae. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andrewsarchus
''Andrewsarchus'' () is an extinct genus of mammal that lived during the middle Eocene epoch in what is now Inner Mongolia, China. Only one species is usually recognized, ''A. mongoliensis'', known from a single skull of great size discovered in 1923 during the expeditions to Central Asia by the American Museum of Natural History (AMNH). Generally classified as a mesonychid since its original description, most recent studies classify it as an artiodactyl. One study specifically classifies ''Andrewsarchus'' as a member of the clade Cetancodontamorpha, closely related to entelodonts, hippos and cetaceans (members of the infraorder that includes the whales). Taxonomy The only known skull was found at a locality in the lower levels of the middle Eocene Irdin Manha Formation of Inner Mongolia, by the paleontological assistant Kan Chuen Pao during the spring of the second year (1923) of the Central Asiatic Expeditions (CAE) of the AMNH, led by the explorer and naturalist Roy Chapm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paraphyletic
In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, 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 Synapomorphy and apomorphy, synapomorphies and symplesiomorphy, 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 a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyphyletic
A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of convergent evolution. The arrangement of the members of a polyphyletic group is called a polyphyly .. ource for pronunciation./ref> It is contrasted with monophyly and paraphyly. For example, the biological characteristic of warm-bloodedness evolved separately in the ancestors of mammals and the ancestors of birds; "warm-blooded animals" is therefore a polyphyletic grouping. Other examples of polyphyletic groups are algae, C4 photosynthetic plants, and edentates. Many taxonomists aim to avoid homoplasies in grouping taxa together, with a goal to identify and eliminate groups that are found to be polyphyletic. This is often the stimulus for major revisions of the classification schemes. Researchers concerned more with ecology than with systema ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monophyly
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic groups are typically characterised by shared derived characteristics ( synapomorphies), which distinguish organisms in the clade from other organisms. An equivalent term is holophyly. The word "mono-phyly" means "one-tribe" in Greek. Monophyly is contrasted with paraphyly and polyphyly as shown in the second diagram. A ''paraphyletic group'' consists of all of the descendants of a common ancestor minus one or more monophyletic groups. A '' polyphyletic group'' is characterized by convergent features or habits of scientific interest (for example, night-active primates, fruit trees, aquatic insects). The features by which a polyphyletic group is differentiated from others are not inherited from a common ancestor. These definitions have taken ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Museum Of Nature And Science
The is in the northeast corner of Ueno Park in Tokyo. The museum has exhibitions on pre-Meiji period, Meiji science in Japan. It is the venue of the taxidermied bodies of the legendary dogs Hachikō and Taro and Jiro. A life-size blue whale model and a steam locomotive are also on display outside. History file:NMNC02s3200.jpg , Blue whale Life size model. Opened in 1871, it has had several names, including Ministry of Education Museum, Tokyo Museum, Tokyo Science Museum, the National Science Museum of Japan, and the National Museum of Nature and Science as of 2007. It was renovated in the 1990s and 2000s, and offers a wide variety of natural history exhibitions and interactive scientific experiences. It was completed as the main building of the Tokyo Science Museum in September 1931 as part of the reconstruction project after the Great Kanto Earthquake. Neo-Renaissance style. Designed by Kenzo Akitani, an engineer of the Ministry of Education, Culture, Sports, Science and Tec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hippopotamid
Hippopotamidae is a family of stout, naked-skinned, and semiaquatic artiodactyl mammals, possessing three-chambered stomachs and walking on four toes on each foot. While they resemble pigs physiologically, their closest living relatives are the cetaceans. They are formally referred to as hippopotamids. There are two living species of hippopotamid in two genera; the pygmy hippo, ''Choeropsis liberiensis'' of the forests of west Africa, and the common hippo, ''Hippopotamus amphibius''. The term ''hippopotamus'' can also be applied to hippopotamids in general, although it is most frequently used for the common hippo and its respective genus. Characteristics Hippopotamids are large mammals, with short, stumpy legs, and barrel-shaped bodies. They have large heads, with broad mouths, and nostrils placed at the top of their snouts. Like pigs, they have four toes, but unlike pigs, all of the toes are used in walking. Hippopotamids are unguligrade, although, unlike most other such a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convergent Evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is homoplasy. The recurrent evolution of flight is a classic example, as flying insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are ''analogous'', whereas '' homologous'' structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different traits. Convergent evolution is similar to parallel evo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
