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Velocisaurinae
Noasauridae is an extinct family of theropod dinosaurs belonging to the group Ceratosauria. They were closely related to the short-armed abelisaurids, although most noasaurids had much more traditional body types generally similar to other theropods. Their heads, on the other hand, had unusual adaptations depending on the subfamily. 'Traditional' noasaurids, sometimes grouped in the subfamily Noasaurinae, had sharp teeth which splayed outwards from a downturned lower jaw. The most complete and well-known example of these kinds of noasaurids was ''Masiakasaurus knopfleri'' from Madagascar. Another group, Elaphrosaurinae, has also been placed within Noasauridae by some studies. Elaphrosaurines developed toothless jaws and herbivorous diets, at least as adults. The most complete and well known elaphrosaurine was ''Limusaurus inextricabilis''. At least some noasaurids had pneumatised cervical vertebrae.Arthur Souza Brum, Elaine Batista Machado, Diogenes de Almeida Campos & A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Velocisaurus
''Velocisaurus'' ("swift lizard") is a genus of noasaurid theropod dinosaur from the Late Cretaceous period of Argentina. Description ''Velocisaurus'' was probably around long, based on a tibia length of . This makes it the smallest noasaurid, after ''Berthasaura''. The foot is unique in that the middle (third) metatarsal has become the main weight-bearing element. Its upper end has thickened whereas the shafts of the adjoining second and fourth metatarsals have thinned considerably. Such a configuration is unknown for other theropods, including birds. Bonaparte explained it as an adaptation for a cursorial (running) lifestyle. The high speed would have been necessary to escape larger theropods; Bonaparte suggested that ''Velocisaurus'' was itself an omnivore, as indicated by the fact that the sole claw found, of the fourth toe, was not trenchant but relatively straight. ''Velocisaurus'' can be characterized by several traits unknown in other Abelisauroids. These include: * ... [...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] |
Humerus
The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a rounded head, a narrow neck, and two short processes (tubercles, sometimes called tuberosities). The body is cylindrical in its upper portion, and more prismatic below. The lower extremity consists of 2 epicondyles, 2 processes (trochlea & capitulum), and 3 fossae (radial fossa, coronoid fossa, and olecranon fossa). As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to fracture, thus often becoming the focus of surgeons. Etymology The word "humerus" is derived from la, humerus, umerus meaning upper arm, shoulder, and is linguistically related to Gothic ''ams'' shoulder and Greek ''ōmos''. Structure Upper extremity The upper or pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scapulocoracoid
The scapulocoracoid is the unit of the pectoral girdle that contains the coracoid and scapula. The coracoid itself is a beak-shaped bone that is commonly found in most vertebrates with a few exceptions. The scapula is commonly known as the ''shoulder blade''. The humerus is linked to the body via the scapula, and the clavicle is connected to the sternum via the scapula as well. Theria Theria (; Greek: , wild beast) is a subclass of mammals amongst the Theriiformes. Theria includes the eutherians (including the placental mammals) and the metatherians (including the marsupials) but excludes the egg-laying monotremes. Ch ...n mammals lack a scapulocoracoid. References * Vertebrates Comparative Anatomy, Function, Evolution by Kenneth V. Kardong. Page 325. Vertebrate anatomy {{Vertebrate anatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coracoid
A coracoid (from Greek κόραξ, ''koraks'', raven) is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is present as part of the scapula, but this is not homologous with the coracoid bone of most other vertebrates. In other tetrapods it joins the scapula to the front end of the sternum and has a notch on the dorsal surface which, along with a similar notch on the ventral surface of the scapula, forms the socket in which the proximal end of the humerus (upper arm bone) is located. The acrocoracoid process is an expansion adjacent to this contact surface, to which the shoulderward end of the biceps brachii muscle attaches in these animals. In birds (and generally theropods and related animals), the entire unit is rigid and called scapulocoracoid. This plays a major role in bird flight. In dinosaurs the main bones of the pectoral girdle were the sca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scapula
The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on either side of the body being roughly a mirror image of the other. The name derives from the Classical Latin word for trowel or small shovel, which it was thought to resemble. In compound terms, the prefix omo- is used for the shoulder blade in medical terminology. This prefix is derived from ὦμος (ōmos), the Ancient Greek word for shoulder, and is cognate with the Latin , which in Latin signifies either the shoulder or the upper arm bone. The scapula forms the back of the shoulder girdle. In humans, it is a flat bone, roughly triangular in shape, placed on a posterolateral aspect of the thoracic cage. Structure The scapula is a thick, flat bone lying on the thoracic wall that provides an attachment for three groups of muscles: intrin ... [...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] |
Masiakasaurus Knopfleri Skull Reconstruction
''Masiakasaurus'' is a genus of small predatory noasaurid theropod dinosaurs from the Late Cretaceous of Madagascar. In Malagasy, ''masiaka'' means "vicious"; thus, the genus name means "vicious lizard". The type species, ''Masiakasaurus knopfleri'', was named after the musician Mark Knopfler, whose music inspired the expedition crew. It was named in 2001 by Scott D. Sampson, Matthew Carrano, and Catherine A. Forster. Unlike most theropods, the front teeth of ''M. knopfleri'' projected forward instead of straight down. This unique dentition suggests that they had a specialized diet, perhaps including fish and other small prey. Other bones of the skeleton indicate that ''Masiakasaurus'' were bipedal, with much shorter forelimbs than hindlimbs. ''M. knopfleri'' was a small theropod, reaching long and weighing . ''Masiakasaurus'' lived around 70 million years ago, along with animals such as ''Majungasaurus'', ''Rapetosaurus'', and ''Rahonavis''. ''Masiakasaurus'' was a member of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carnotaurus
''Carnotaurus'' (; ) is a genus of theropod dinosaur that lived in South America during the Late Cretaceous period, probably sometime between 71 and 69 million years ago. The only species is ''Carnotaurus sastrei''. Known from a single well-preserved skeleton, it is one of the best-understood theropods from the Southern Hemisphere. The skeleton, found in 1984, was uncovered in the Chubut Province of Argentina from rocks of the La Colonia Formation. ''Carnotaurus'' is a derived member of the Abelisauridae, a group of large theropods that occupied the large predatorial niche in the southern landmasses of Gondwana during the late Cretaceous. Within the Abelisauridae, the genus is often considered a member of the Brachyrostra, a clade of short-snouted forms restricted to South America. ''Carnotaurus'' was a lightly built, bipedal predator, measuring in length and weighing . As a theropod, ''Carnotaurus'' was highly specialized and distinctive. It had thick horns above the eyes, ... [...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] |
Abelisauridae
Abelisauridae (meaning "Abel's lizards") is a family (or clade) of ceratosaurian theropod dinosaurs. Abelisaurids thrived during the Cretaceous period, on the ancient southern supercontinent of Gondwana, and today their fossil remains are found on the modern continents of Africa and South America, as well as on the Indian subcontinent and the island of Madagascar. Isolated teeth were found in the Late Jurassic of Portugal, and the Late Cretaceous genera '' Tarascosaurus'' and ''Arcovenator'' have been described in France. Abelisaurids first appear in the fossil record of the early middle Jurassic period, and at least two genera (the Moroccan ''Chenanisaurus'' and the Madagascan ''Majungasaurus'') survived until the end of the Mesozoic era 66 million years ago. Like most theropods, abelisaurids were carnivorous bipeds. They were characterized by stocky hind limbs and extensive ornamentation of the skull bones, with grooves and pits. In many abelisaurids, such as ''Carnotaurus'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceratosauria
Ceratosaurs are members of the clade Ceratosauria, a group of dinosaurs defined as all theropods sharing a more recent common ancestor with ''Ceratosaurus'' than with birds. The oldest known ceratosaur, ''Saltriovenator'', dates to the earliest part of the Jurassic, around 199 million years ago. According to the majority of the latest research, Ceratosauria includes three major clades: Ceratosauridae, Noasauridae, and Abelisauridae, found primarily (though not exclusively) in the Southern Hemisphere. Originally, Ceratosauria included the above dinosaurs plus the Late Triassic to Early Jurassic Coelophysoidea and Dilophosauridae, implying a much earlier divergence of ceratosaurs from other theropods. However, most recent studies have shown that coelophysoids and dilophosaurids do not form a natural group with other ceratosaurs, and are excluded from this group. Ceratosauria derives its names from the type species, ''Ceratosaurus nasicornis'', described by O.C. Marsh in 1884. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
