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Avimimus Portentosus
''Avimimus'' ( ), meaning "bird mimic" (Latin ''avis'' = bird + ''mimus'' = mimic), is a genus of oviraptorosaurian theropod dinosaur, named for its bird-like characteristics, that lived in the late Cretaceous in what is now Mongolia, around 85 to 70 million years ago. Description ''Avimimus'' was a small, bird-like dinosaur with a length of 1.5 m (5 ft). The skull was small compared to the body, though the brain and eyes were large. The size of the bones which surrounded the brain and were dedicated to protecting it are large. This is also consistent with the hypothesis that ''Avimimus'' had a proportionally large brain. The jaws of ''Avimimus'' were thought to form a parrot-like beak lacking teeth, and a thorough review of the holotype specimen's anatomy confirmed that no teeth were preserved, although a series of tooth-like projections along the tip of the premaxilla were. However, subsequently discovered specimens have been reported to preserve small pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period. Climate During the Late Cretaceous, the climate was warmer than present, although throughout the period a cooling trend is evident. The tropics became restricted to equatorial regions and northern latitudes experienced markedly more seasonal climatic conditions. Geography Due to plate tectonics, the Americas were gradually moving westward, causing the Atlantic Ocean to expand. The Western Interior Seaway divided North America into eastern and western halves; Appalachia and Laramidia. India maintained a northward course towards Asia. In the Southern Hemisphere, Australia and Ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foramen Magnum
The foramen magnum ( la, great hole) is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblongata, passes through the foramen magnum as it exits the cranial cavity. Apart from the transmission of the medulla oblongata and its membranes, the foramen magnum transmits the vertebral arteries, the anterior and posterior spinal arteries, the tectorial membranes and alar ligaments. It also transmits the accessory nerve into the skull. The foramen magnum is a very important feature in bipedal mammals. One of the attributes of a biped's foramen magnum is a forward shift of the anterior border of the cerebellar tentorium; this is caused by the shortening of the cranial base. Studies on the foramen magnum position have shown a connection to the functional influences of both posture and locomotion. The forward shift of the foramen magnum i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Djadokta Formation
The Djadochta Formation (sometimes transcribed and also known as Djadokhta, Djadokata, or Dzhadokhtskaya) is a highly fossiliferous geological formation situated in Central Asia, Gobi Desert, dating from the Late Cretaceous period, about 75 million to 71 million years ago. The type locality is the Bayn Dzak locality, famously known as the Flaming Cliffs. Dinosaur, mammal, and other reptile remains are among the fossils that have been recovered from the formation. Excavation history The Djadochta Formation was first documented and explored—though only a single locality—during paleontological expeditions of the American Museum of Natural History in 1922–1925, which were part of the Central Asiatic Expeditions. The expeditions were led by Roy Chapman Andrews, in company of Walter Willis Granger as chief paleontologist and field team. The team did extensive exploration at the Bayn Dzak (formerly Shabarakh Usu) region, which they nicknamed Flaming Cliffs given that at sunset ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avimimus Portentosus
''Avimimus'' ( ), meaning "bird mimic" (Latin ''avis'' = bird + ''mimus'' = mimic), is a genus of oviraptorosaurian theropod dinosaur, named for its bird-like characteristics, that lived in the late Cretaceous in what is now Mongolia, around 85 to 70 million years ago. Description ''Avimimus'' was a small, bird-like dinosaur with a length of 1.5 m (5 ft). The skull was small compared to the body, though the brain and eyes were large. The size of the bones which surrounded the brain and were dedicated to protecting it are large. This is also consistent with the hypothesis that ''Avimimus'' had a proportionally large brain. The jaws of ''Avimimus'' were thought to form a parrot-like beak lacking teeth, and a thorough review of the holotype specimen's anatomy confirmed that no teeth were preserved, although a series of tooth-like projections along the tip of the premaxilla were. However, subsequently discovered specimens have been reported to preserve small pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cursorial
A cursorial organism is one that is adapted specifically to run. An animal can be considered cursorial if it has the ability to run fast (e.g. cheetah) or if it can keep a constant speed for a long distance (high endurance). "Cursorial" is often used to categorize a certain locomotor mode, which is helpful for biologists who examine behaviors of different animals and the way they move in their environment. Cursorial adaptations can be identified by morphological characteristics (e.g. loss of lateral digits as in ungulate species), physiological characteristics, maximum speed, and how often running is used in life. There is much debate over how to define a cursorial animal specifically. The most accepted definitions include that a cursorial organism could be considered adapted to long-distance running at high speeds or has the ability to accelerate quickly over short distances. Among vertebrates, animals under 1 kg of mass are rarely considered cursorial, and cursorial behaviors ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tail
The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds. While tails are primarily a feature of vertebrates, some invertebrates including scorpions and springtails, as well as snails and slugs, have tail-like appendages that are sometimes referred to as tails. Tailed objects are sometimes referred to as "caudate" and the part of the body associated with or proximal to the tail are given the adjective "caudal". Function Animal tails are used in a variety of ways. They provide a source of locomotion for fish and some other forms of marine life. Many land animals use their tails to brush away flies and other biting insects. Most canines use their tails to comunicate mood and intention . Some species, including cats and kangaroos, use their tails for balance; and some, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quill Knob
The pennaceous feather is a type of feather present in most modern birds and in some other species of maniraptoriform dinosaurs. Description A pennaceous feather has a stalk or quill. Its basal part, called a ''calamus'', is embedded in the skin. The calamus is hollow and has pith formed from the dry remains of the feather pulp, and the calamus opens below by an ''inferior umbilicus'' and above by a ''superior umbilicus''. The stalk above the calamus is a solid ''rachis'' having an umbilical groove on its underside. Pennaceous feathers have a rachis with ''vanes'' or ''vaxillum '' spreading to either side. These vanes are composed of a high number of flattened ''barbs'', that are connected to one another with ''barbules''. The barbules are tiny strands that criss-cross on the flattened sides of the barbs. This forms a miniature velcro-like mesh that holds all the barbs together, stabilizing the vanes. Pennaceous feathers on the wing, and elsewhere that stresses related to fligh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ulna
The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of the forearm as the little finger. It runs parallel to the radius, the other long bone in the forearm. The ulna is usually slightly longer than the radius, but the radius is thicker. Therefore, the radius is considered to be the larger of the two. Structure The ulna is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. It is broader close to the elbow, and narrows as it approaches the wrist. Close to the elbow, the ulna has a bony process, the olecranon process, a hook-like structure that fits into the olecranon fossa of the humerus. This prevents hyperextension and forms a hinge joint with the trochlea of the humerus. There is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avimimus Mmartyniuk Wiki
''Avimimus'' ( ), meaning "bird mimic" (Latin ''avis'' = bird + ''mimus'' = mimic), is a genus of oviraptorosaurian theropod dinosaur, named for its bird-like characteristics, that lived in the late Cretaceous in what is now Mongolia, around 85 to 70 million years ago. Description ''Avimimus'' was a small, bird-like dinosaur with a length of 1.5 m (5 ft). The skull was small compared to the body, though the brain and eyes were large. The size of the bones which surrounded the brain and were dedicated to protecting it are large. This is also consistent with the hypothesis that ''Avimimus'' had a proportionally large brain. The jaws of ''Avimimus'' were thought to form a parrot-like beak lacking teeth, and a thorough review of the holotype specimen's anatomy confirmed that no teeth were preserved, although a series of tooth-like projections along the tip of the premaxilla were. However, subsequently discovered specimens have been reported to preserve small pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Sacs
Air sacs are spaces within an organism where there is the constant presence of air. Among modern animals, birds possess the most air sacs (9–11), with their extinct dinosaurian relatives showing a great increase in the pneumatization (presence of air) in their bones. Theropods, like ''Aerosteon'', have many air sacs in the body that are not just in bones, and they can be identified as the more primitive form of modern bird airways. Sauropods are well known for the number of air pockets in their bones (especially vertebra), although one theropod, '' Deinocheirus'', shows a rivalling number of air pockets. Function From about 1870 onwards scientists have generally agreed that the post-cranial skeletons of many dinosaurs contained many air-filled cavities ( postcranial skeletal pneumaticity), especially in the vertebrae. Pneumatization of the skull (such as paranasal sinuses) is found in both synapsids and archosaurs, but postcranial pneumatization is found only in birds, non-avia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebra
The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic irregular bone whose complex structure is composed primarily of bone, and secondarily of hyaline cartilage. They show variation in the proportion contributed by these two tissue types; such variations correlate on one hand with the cerebral/caudal rank (i.e., location within the backbone), and on the other with phylogenetic differences among the vertebrate taxa. The basic configuration of a vertebra varies, but the bone is its ''body'', with the central part of the body constituting the ''centrum''. The upper (closer to) and lower (further from), respectively, the cranium and its central nervous system surfaces of the vertebra body support attachment to the intervertebral discs. The posterior part of a vertebra forms a vertebral arch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caenagnathid
Caenagnathidae is a family of bird-like maniraptoran theropod dinosaurs from the Cretaceous of North America and Asia. They are a member of the Oviraptorosauria, and close relatives of the Oviraptoridae. Like other oviraptorosaurs, caenagnathids had specialized beaks, long necks, and short tails, and would have been covered in feathers. The relationships of caenagnathids were long a puzzle. The family was originally named by Raymond Martin Sternberg in 1940 as a family of flightless birds. The discovery of skeletons of the related oviraptorids revealed that they were in fact non-avian theropods, and the discovery of more complete caenagnathid remains revealed that ''Chirostenotes pergracilis'', originally named on the basis of a pair of hands, and ''Citipes elegans'', originally thought to be an ornithomimid, named from a foot, were caenagnathids as well. Anatomy Overall, the anatomy of the caenagnathids is similar to that of the closely related Oviraptoridae, but there are a n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
