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Eutheria (beetle)
Eutheria (; from Greek , 'good, right' and , 'beast'; ) is the clade consisting of all therian mammals that are more closely related to placentals than to marsupials. Eutherians are distinguished from noneutherians by various phenotypic traits of the feet, ankles, jaws and teeth. All extant eutherians lack epipubic bones, which are present in all other living mammals (marsupials and monotremes). This allows for expansion of the abdomen during pregnancy. The oldest-known eutherian species is ''Juramaia sinensis'', dated at from the early Late Jurassic ( Oxfordian) of China. Eutheria was named in 1872 by Theodore Gill; in 1880 Thomas Henry Huxley defined it to encompass a more broadly defined group than Placentalia. Characteristics Distinguishing features are: *an enlarged malleolus ("little hammer") at the bottom of the tibia, the larger of the two shin bones *the joint between the first metatarsal bone and the entocuneiform bone (the innermost of the three cuneiform ... [...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 dinosau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malleolus
A malleolus is the bony prominence on each side of the human ankle. Each leg is supported by two bones, the tibia on the inner side (medial) of the leg and the fibula on the outer side (lateral) of the leg. The medial malleolus is the prominence on the inner side of the ankle, formed by the lower end of the tibia. The lateral malleolus is the prominence on the outer side of the ankle, formed by the lower end of the fibula. The word ''malleolus'' (), plural ''malleoli'' (), comes from Latin and means "small hammer". (It is cognate with ''mallet''.) Medial malleolus The medial malleolus is found at the foot end of the tibia. The medial surface of the lower extremity of tibia is prolonged downward to form a strong pyramidal process, flattened from without inward - the medial malleolus. * The ''medial surface'' of this process is convex and subcutaneous. * The ''lateral'' or ''articular surface'' is smooth and slightly concave, and articulates with the talus. * The ''anterior bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acristatherium
''Acristatherium yanensis'' is an extinct basal eutherian from the Early Cretaceous (early Aptian, about ) Lujiatun Bed of the Yixian Formation. It was described on the basis of a single specimen (holotype) from Beipiao, Liaoning, China, by Yaoming Hu, Jin Meng, Chuankui Li, and Yuanqing Wang in 2010. The specimen comprises a partial skull, long. It appears to possess a vestige of a septomaxilla, a feature only otherwise seen in nonmammalian 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 ...s. References Prehistoric eutherians Early Cretaceous mammals of Asia Fossil taxa described in 2010 Prehistoric mammal genera {{cretaceous-mammal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zhelestidae
Zhelestidae is a lineage of extinct eutherian mammals. Occurring in the Late Cretaceous from the Turonian to the Maastrichtian, they were an extremely successful group, with representatives present in Europe, Asia, India (and subsequently in Madagascar), Africa and North America, ostensibly rendering them a cosmopolitan clade. They were specialised towards an herbivorous lifestyle and were in fact initially considered stem-ungulates, but the presence of epipubics and "archaic" dental characters render them as non-placental eutherians. Range The earliest zhelestid remains occur in the of . By the |
Adapisoriculidae
Adapisoriculidae is an extinct family of non-placental eutherian mammals present during the Paleogene and possibly the Late Cretaceous. They were once thought to be members of the order Erinaceomorpha, closely related to the hedgehog family (Erinaceidae), because of their similar dentition, or to be basal Euarchontans. They were also thought to be marsupials at one point. Most recent studies show them to be non-placental eutherians, however.Carly L. Manz, Stephen G. B. Chester, Jonathan I. Bloch, Mary T. Silcox, Eric J. Sargis, New partial skeletons of Palaeocene Nyctitheriidae and evaluation of proposed euarchontan affinities, Published 14 January 2015.DOI: 10.1098/rsbl.2014.0911 They were small mammals of about 15 cm long, with a tail of equal length. They were probably nocturnal, eating insects and fruits. '' Deccanolestes'' and '' Sahnitherium'' from the Late Cretaceous of India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zalambdalestidae
Zalambdalestidae is a clade of Asian eutherians occurring during the Late Cretaceous. Once classified as Glires, features like epipubic bones and various cranial elements have identified these animals as outside of Placentalia, representing thus a specialised clade of non-placental eutherians without any living descendants, and potentially rather different from modern placentals in at least reproductive anatomy. Taxonomy The exact position of Zalambdalestidae within Eutheria varies, though they are generally agreed to be more basal than zhelestids. Currently, the clade includes the genera ''Zalambdalestes'', '' Alymlestes'', '' Anchilestes'', '' Barunlestes'', '' Kulbeckia'', '' Zhangolestes'' and '' Zofialestes''. Palaeobiology Zalambdaltestids were insectivores, having zalambdodont molars much as various modern insectivorous species. They are uniquely suited to a saltatorial, cursorial lifestyle, bearing long, semi-digitigrade limbs and a spinal column similar to that of mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leptictida
Leptictida (''leptos iktis'' "small/slender weasel") is a possibly paraphyletic extinct order of eutherian mammals. Their classification is contentious: according to cladistic studies, they may be (distantly) related to Euarchontoglires (rodents, primates and their relatives), although they are more recently regarded as the first branch to split from basal eutherians. One recent large-scale cladistic analysis of eutherian mammals favored lepictidans as close to the placental crown-clade; and several other recent analyses that included data from Cretaceous non-eutherian mammals found ''Leptictis'' to belong to the superorder Afrotheria. The most recent phylogenetic studies recover it as actually a paraphyletic assemblage leading to Placentalia. Description The leptictids are a characteristic example of the non-specialized placental mammals that took part in the late Cretaceous-Paleocene evolutionary radiation, originally bunched together in the order Insectivora. The leptictids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cimolesta
Cimolesta is an extinct order of non-placental eutherian mammals. Cimolestans had a wide variety of body shapes, dentition and lifestyles, though the majority of them were small to medium-sized general mammals that bore superficial resemblances to rodents, lagomorphs, mustelids, and marsupials. Several groups have previously been suggested to have descended from the Cimolesta: the Pholidota (which would have been regarded as a suborder of Cimolesta), the Creodonta, and the Carnivora. The origins of the enigmatic Dinocerata have been suggested to lie within the Cimolesta as well. However, recent studies have revealed that cimolestans are more likely to be basal, non-placental eutherians, with no living descendants. Some experts had placed the pangolins within Cimolesta, though the current consensus is that the pangolins should be placed within their own order, Pholidota, as a sister taxon to Carnivora within Ferae. Some have also placed the enigmatic family Ptolemaiidae within Ci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asioryctitheria
Asioryctitheria ("Asian digging beasts") is an extinct order of early eutherians. Skull structure With the exception of '' Prokennalestes'', these advanced forms lacked a Meckelian groove. Furthermore, they were equipped with double-rooted canines, a lower premolar with a reduced or absent metaconid and a more elongated lower premolar than their predecessors. In addition, the entoconid and hypoconulid on the lower molars are untwinned, the entotympanic is non-existent, the alisphenoid is enlarged, a Vidian foramen is present as well as a promontorium linked to the paroccipital process via the crista interfenestralis. Classification Asioryctitheria contains at least four genera and two families.Mikko's Phylogeny ArchivPaleofile.com (net, info) . * '' Sasayamamylos kawaii'' Kusuhashi et al. 2013 * Kennalestidae ''Kennalestes'' is an extinct genus of insectivorous mammal resembling a shrew that was described in 1968.Z. Kielan-Jaworowska. 1968. New Upper Cretaceous multi ... [...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 situate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
