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Eomaia
''Eomaia'' ("dawn mother") is a genus of extinct fossil mammals containing the single species ''Eomaia scansoria'', discovered in rocks that were found in the Yixian Formation, Liaoning Province, China, and dated to the Barremian Age of the Lower Cretaceous about . The single fossil specimen of this species is in length and virtually complete. An estimate of the body weight is between . It is exceptionally well-preserved for a 125-million-year-old specimen. Although the fossil's skull is squashed flat, its teeth, tiny foot bones, cartilages and even its fur are visible. Description The ''Eomaia'' fossil shows clear traces of hair. However, this is not the earliest clear evidence of hair in the mammalian lineage, as fossils of '' Volaticotherium'', and the docodont ''Castorocauda'', discovered in rocks dated to about , also have traces of fur. ''Eomaia scansoria'' possessed several features in common with placental mammals that distinguish them from metatherians, the group that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eomaia Scansoria 54
''Eomaia'' ("dawn mother") is a genus of extinct fossil mammals containing the single species ''Eomaia scansoria'', discovered in rocks that were found in the Yixian Formation, Liaoning Province, China, and dated to the Barremian Age of the Lower Cretaceous about . The single fossil specimen of this species is in length and virtually complete. An estimate of the body weight is between . It is exceptionally well-preserved for a 125-million-year-old specimen. Although the fossil's skull is squashed flat, its teeth, tiny foot bones, cartilages and even its fur are visible. Description The ''Eomaia'' fossil shows clear traces of hair. However, this is not the earliest clear evidence of hair in the mammalian lineage, as fossils of ''Volaticotherium'', and the docodont '' Castorocauda'', discovered in rocks dated to about , also have traces of fur. ''Eomaia scansoria'' possessed several features in common with placental mammals that distinguish them from metatherians, the group t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eomaia NT
''Eomaia'' ("dawn mother") is a genus of extinct fossil mammals containing the single species ''Eomaia scansoria'', discovered in rocks that were found in the Yixian Formation, Liaoning Province, China, and dated to the Barremian Age of the Lower Cretaceous about . The single fossil specimen of this species is in length and virtually complete. An estimate of the body weight is between . It is exceptionally well-preserved for a 125-million-year-old specimen. Although the fossil's skull is squashed flat, its teeth, tiny foot bones, cartilages and even its fur are visible. Description The ''Eomaia'' fossil shows clear traces of hair. However, this is not the earliest clear evidence of hair in the mammalian lineage, as fossils of ''Volaticotherium'', and the docodont '' Castorocauda'', discovered in rocks dated to about , also have traces of fur. ''Eomaia scansoria'' possessed several features in common with placental mammals that distinguish them from metatherians, the group t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles (including birds) from which they diverged in the Carboniferous, over 300 million years ago. Around 6,400 extant species of mammals have been described divided into 29 orders. The largest orders, in terms of number of species, are the rodents, bats, and Eulipotyphla ( hedgehogs, moles, shrews, and others). The next three are the Primates (including humans, apes, monkeys, and others), the Artiodactyla (cetaceans and even-toed ungulates), and the Carnivora ( cats, dogs, seals, and others). In terms of cladistics, which reflects evolutionary history, mammals are the only living members of the Synapsida (synapsids); this clade, toget ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liaoning
Liaoning () is a coastal province in Northeast China that is the smallest, southernmost, and most populous province in the region. With its capital at Shenyang, it is located on the northern shore of the Yellow Sea, and is the northernmost coastal province of the People's Republic of China. Historically a gateway between China proper and Manchuria, the modern Liaoning province was established in 1907 as Fengtian or Fengtien province and was renamed Liaoning in 1929. It was also known at that time as Mukden Province for the Manchu name of ''Shengjing'', the former name of Shenyang. Under the Japanese-puppet Manchukuo regime, the province reverted to its 1907 name, but the name Liaoning was restored for a brief time in 1945 and then again in 1954. Liaoning borders the Yellow Sea ( Korea Bay) and Bohai Sea in the south, North Korea's North Pyongan and Chagang provinces in the southeast, Jilin to the northeast, Hebei to the southwest, and Inner Mongolia to the n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mortise And Tenon
A mortise and tenon (occasionally mortice and tenon) joint connects two pieces of wood or other material. Woodworkers around the world have used it for thousands of years to join pieces of wood, mainly when the adjoining pieces connect at right angles. Mortise and tenon joints are strong and stable joints that can be used in many projects. They furnish a strong outcome and connect by either gluing or locking into place. The mortise and tenon joint also gives an attractive look. One drawback to this joint is the difficulty in making it because of the precise measuring and tight cutting required. In its most basic form, a mortise and tenon joint is both simple and strong. There are many variations of this type of joint, and the basic mortise and tenon has two components: #the mortise hole, and #the tenon tongue. The tenon, formed on the end of a member generally referred to as a rail, fits into a square or rectangular hole cut into the other, corresponding member. The tenon is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dental Formula
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology (that is, the relationship between the shape and form of the tooth in question and its inferred function) of the teeth of an animal. Animals whose teeth are all of the same type, such as most non-mammalian vertebrates, are said to have ''homodont'' dentition, whereas those whose teeth differ morphologically are said to have ''heterodont'' dentition. The dentition of animals with two successions of teeth (deciduous, permanent) is referred to as ''diphyodont'', while the dentition of animals with only one set of teeth throughout life is ''monophyodont''. The dentition of animals in which the teeth are continuously discarded and replaced throughout life is termed ''polyphyodont''. The dentition of animals in which the teeth are set in sock ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epipubic Bones
Epipubic bones are a pair of bones projecting forward from the pelvic bones of modern marsupials, monotremes and fossil mammals like multituberculates, and even basal eutherians (the ancestors of placental mammals, who lack them). They first occur in non-mammalian cynodonts such as tritylodontids, suggesting that they are a synapomorphy between them and Mammaliformes. They were first described as early as 1698, but to date, their function(s) remain unresolved. Epipubic bones are often called ''marsupial bones'' because they support the mother's pouch in modern marsupials ("''marsupium''" is Latin for "pouch"). Function Some writers have suggested that the epipubic bones are a part of a kinetic link stretching from the femur on one side, to the ribs on the opposite side. This linkage is formed by a series of muscles: Each epipubic bone is connected to the femur by the pectineus muscle, and to the ribs and vertebrae by the pyramidalis, rectus abdominis, and external and int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monotremes
Monotremes () are prototherian mammals of the order Monotremata. They are one of the three groups of living mammals, along with placentals (Eutheria), and marsupials ( Metatheria). Monotremes are typified by structural differences in their brains, jaws, digestive tract, reproductive tract, and other body parts, compared to the more common mammalian types. In addition, they lay eggs rather than bearing live young, but, like all mammals, the female monotremes nurse their young with milk. Monotremes have been considered members of Australosphenida, a clade that contains extinct mammals from the Jurassic and Cretaceous of Madagascar, South America, and Australia, though this is disputed. The only surviving examples of monotremes are all indigenous to Australia and New Guinea, although there is evidence that they were once more widespread, as '' Monotrematum'' is known from the Paleocene of South America. The extant monotreme species are the platypus and four species of echidna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cynodont
The cynodonts () (clade Cynodontia) are a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 mya), and extensively diversified after the Permian–Triassic extinction event. Cynodonts had a wide variety of lifestyles, including carnivory and herbivory. Mammals are cynodonts, as are their extinct ancestors and close relatives, having evolved from advanced probainognathian cynodonts during the Late Triassic. All other cynodont lines went extinct, with the last known non-mammalian cynodont group, the Tritylodontidae, having its youngest records in the Early Cretaceous. Description Early cynodonts have many of the skeletal characteristics of mammals. The teeth were fully differentiated and the braincase bulged at the back of the head. Outside of some crown-group mammals (notably the therians), all cynodonts probably laid eggs. The temporal fenestrae were much larger than those of their ancestors, and the widening of the zygomatic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Cretaceous
The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Megaannum#SI prefix multipliers, Ma to 100.5 Ma. Geology Proposals for the exact age of the Barremian-Aptian boundary ranged from 126 to 117 Ma until recently (as of 2019), but based on drillholes in Svalbard the defining Anoxic event#Cretaceous, early Aptian Oceanic Anoxic Event 1a (OAE1a) was carbon isotope dated to 123.1±0.3 Ma, limiting the possible range for the boundary to c. 122–121 Ma. There is a possible link between this anoxic event and a series of Early Cretaceous large igneous provinces (LIP). The Ontong Java Plateau, Ontong Java-Manihiki Plateau, Manihiki-Hikurangi Plateau, Hikurangi large igneous province, emplaced in the South Pacific at c. 120 Ma, is by far the largest LIP in Earth's history. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Therapsid
Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more underneath the body, as opposed to the sprawling posture of many reptiles and salamanders. Therapsids evolved from " pelycosaurs", specifically within the Sphenacodontia, more than 279.5 million years ago. They replaced the "pelycosaurs" as the dominant large land animals in the Middle Permian through to the Early Triassic. In the aftermath of the Permian–Triassic extinction event, therapsids declined in relative importance to the rapidly diversifying reptiles during the Middle Triassic. The therapsids include the cynodonts, the group that gave rise to mammals (Mammaliaformes) in the Late Triassic, around 225 million years ago. Of the non-mammalian therapsids, only cynodonts survived beyond the end of the Triassic, with the only oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cuneiform Bones
There are three cuneiform ("wedge-shaped") bones in the human foot: * the first or medial cuneiform * the second or intermediate cuneiform, also known as the middle cuneiform * the third or lateral cuneiform They are located between the navicular bone and the first, second and third metatarsal bones and are medial to the cuboid bone. Structure There are three cuneiform bones: # The medial cuneiform (also known as first cuneiform) is the largest of the cuneiforms. It is situated at the medial side of the foot, anterior to the navicular bone and posterior to the base of the first metatarsal. Lateral to it is the intermediate cuneiform. It articulates with four bones: the navicular, second cuneiform, and first and second metatarsals. The tibialis anterior and fibularis longus muscle inserts at the medial cuneiform bone. # The intermediate cuneiform (second cuneiform or middle cuneiform) is shaped like a wedge, the thin end pointing downwards. The intermediate cuneiform is si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
